Microprocessor-based electronic engine control system

• US 4,255,789 A
• Filed: 02/27/1978
• Issued: 03/10/1981
• Est. Priority Date: 02/27/1978
• Status: Expired due to Term

• Current Assignee: Siemens-Bendix Automotive Electronics LP
• Original Assignee: The Bendix Corporation (Honeywell International Inc.)
• Inventors: Russo, Frank A., Johnson, Edwin A., Hartford, Thomas W.
• Primary Examiner(s): Gruber, Felix D.
• Application Number:
  US05/881,321
• Time in Patent Office: 1,107 Days
• Field of Search: 364/424, 364/431, 364/442, 364/200, 364/900, 364/550, 123/32 EB, 123/32 EE, 123/32 EH, 123/32 EC, 123/32 EA, 123/117 D, 123/117 R, 123/119 EC, 340/347 AD, 235/304.1
• US Class Current: 701/108
• CPC Class Codes: F02D 41/263 the program execution being modifiable by physical parameters
• CPC Class Codes: F02D 41/266 the computer being backed-up or assisted by another circuit, e.g. analogue
• CPC Class Codes: F02P 5/1502 using one central computing unit
• CPC Class Codes: H02H 3/24 responsive to undervoltage or no-voltage H02H3/207 takes precedence
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

A method and apparatus for controlling the various functions of an internal combustion engine using a program-controlled microprocessor having a memory preprogrammed with various control laws and associated control schedules receives information concerning one or more engine operating parameters such as manifold pressure, throttle position, engine coolant temperature, air temperature, and engine speed or period and the like. These parameters are sensed and then supplied to input circuits for signal conditioning and conversion to digital words usable by the microprocessor. The microprocessor-based electronic engine control system computes a digital word indicative of a computer-commanded engine control operation and output circuitry responds to predetermined computer-generated commands and to the computed digital command words for converting them to corresponding pulse-width control signals or the like for controlling such engine operations as fuel-injection ignition timing, proportional and/or on-off EGR control, and the like.

Claims

1. In an internal combustion engine having an intake system an exhaust system, an engine block, a plurality of cylinders disposed in said engine block, a piston mounted for reciprocal movement in each of said plurality of cylinders in response to the combustion of air shaft responsive to the reciprocation of said pistons in said cylinders for being drivably rotated thereby, throttle means disposed in said intake system for controlling the air flow into said plurality of cylinders, means responsive to a fuel control signal for selectively supplying a controlled quantity of fuel into a selected one or more of said plurality of cylinders, means responsive to an ignition control signal for selectively controlling the time and duration of the ignition of said fuel in said selected one or more of said plurality of cylinders, means coupling said exhaust system to said intake system for establishing an exhaust gas recirculation path therebetween, means disposed at least partially within said recirculation path and responsive to an exhaust gas recirculation control signal for selectively varying the quantity of exhaust gas recirculated from said exhaust system back to said intake system, an improved electronic engine control system comprising:

means for sensing a plurality of selected engine operating parameters and generating a conditioned sensor output signal indicative of the value of each of said sensed plurality of selected engine operating parameters;

means for generating predetermined command signals to control the processing said output signal;

means responsive to said predetermined command signals for converting a selected one of said conditioned sensor output signals indicative of the value of a selected one of said sensed engine operating parameters into one or more digital words indicative thereof;

memory means for storing data representing look-up tables of control command modifier values for use in computing one or more engine control commands and program means for implementing at least one of preprogrammed fuel control law, ignition control law or exhaust gas recirculation control law;

means responsive to said one or more of said digital words representative of the value of said selected engine operating parameters for addressing said memory means for one or more of said stored look-up tables of modifier values;

computing means including means responsive to each of said addressed look-up tables for computing one or more desired modifier values, said computing means further including program execution means for generating said predetermined command signals and for implementing said at least one pre-programmed control law utilizing said computed modifier values for calculating one or more digital command words indicative of a desired control action to be taken for effecting a predetermined engine control function; and

means responsive to said one or more digital command words for generating a precisely controlled value of at least a selected one of said fuel control signal for selectively controlling the quantity of fuel supplied to a selected one or more of said plurality of cylinders, said ignition control signal for selectively controlling the time and duration of the ignition of said fuel in said selected one or more of said plurality of cylinders, and said exhaust gas recirculation signal for selectively varying the quantity of exhaust gas recirculated from said exhaust system back to said intake system.

2. In an internal combustion engine having an intake system, an exhaust system, an engine block, a plurality of cylinders disposed in said engine block, a piston disposed in each of said plurality of cylinders and mounted for reciprocal movement within each of said cylinders in response to combustion of fuel and air therein, means associated with at least a predetermined one of said cylinders and responsive to said piston reciprocating therein having attained a predetermined reference position for generating an engine position signal indicative thereof, means responsive to a fuel control signal for selectively controlling the quantity of fuel supplied to a selected one or more of said plurality of cylinders, means responsive to an ignition control signal for selectively controlling the time and duration of the ignition of said fuel in said selected one or more of said plurality of cylinders, an improved microprocessor-based engine control system comprising:

means for sensing a plurality of engine operating parameters and generating sensor output signals indicative of the value thereof;

means for generating command signals for processing said sensor output signals;

means for converting a selected one of said sensor output signals into one or more data words representative thereof in response to said processing signals;

means responsive to one or more of said data words for performing predetermined programmed operations thereon in accordance with pre-programmed fuel control laws and ignition timing laws and for generating digital commands indicative of a desired control action for effecting one or more predetermined engine control functions such as fuel pulse injection or ignition timing, the operation thereof being synchronized to the generation of said engine position signals;

means responsive to said digital commands for controlling the generation of a selected one of said fuel control signal or said ignition timing signal thereby accurately controlling the quantity of fuel supplied to a selected one or more of said plurality of cylinders or the time and duration of fuel ignition therein; and

means responsive to said engine position signals for altering the rate at which said digital commands are generated such that certain control functions such as fuel control are up-dated once each revolution until a predetermined engine speed is reached and then once every other revolution thereafter, and other control functions such as ignition timing and the like are updated once every other revolution at low engine speeds and once each revolution after the engine speed reaches a second predetermined level, thereby automatically proportioning the up-dating of said data commands to effectively compensate for changing computing power per engine revolution and hence the number of computations that can be performed per revolution which inherently occur with changes in engine speed.

3. In an internal combustion engine having an engine block, a plurality of cylinders disposed in said engine block, a piston disposed in each of said cylinders and mounted for reciprocal movement therein in response to the combustion of air and fuel in said cylinder, means responsive to a fuel control signal for selectively controlling the supply of fuel into a selected one or more of said plurality of cylinders, means responsive to a digital fuel control command for controlling the generation of said fuel control signal, and an electronic engine control means for implementing a pre-programmed fuel control law to generate said digital fuel control command, the improvement comprising:

external sensing means for generating a signal indicative of the value of engine temperature;

means responsive to said signal indicative of the value of engine temperature for converting said signal into an engine temperature data word representative thereof;

memory means for storing data representative of a look-up table having a predetermined finite number of basic fuel command modifier values representing a continuous control surface having an infinite number of such modifier values;

means responsive to at least said engine temperature data word for addressing said look-up table to obtain at least one predetermined basic fuel command modifier value;

means for interpolating between data representative of said addressed at least one predetermined basic modifier value and the basic modifier values adjacent thereto for accurately computing an optimal modifier value for use by said electronic engine control means in the implementation of said predetermined fuel control law; and

program means for implementing said fuel control law to generate said digital fuel control command, said program means being responsive to said accurately computed optimal modifier value for modifying the value of said digital fuel control command to insure the generation of a more accurate engine temperature-compensated digital fuel control command and hence a more accurate engine temperature-compensated fuel control signal thereby insuring a more accurately controlled supply of fuel into said selected one or more cylinders.

4. In an internal combustion engine having an intake system, an exhaust system, an engine block, a plurality of engine cylinders disposed in said engine block, a piston disposed for reciprocal movement within each of said plurality of cylinders, an output shaft responsive to the reciprocation of said pistons within said cylinders in response to the combustion of fuel and air therein for driveably rotating same, means for selectively supplying fuel into one or more of said cylinders, means responsive to an ignition control pulse for controlling the ignition of said fuel in said cylinders, means for sensing a predetermined position of said piston within said cylinder such as top-dead-center or the like for generating engine position pulses and for obtaining an indication of the speed or period of said engine, and a micro-processor-based electronic engine control system including memory means, the improvement in said microprocessor-based electronic engine control system comprising:

memory means for storing data representative of at least one look-up table for establishing a predetermined multi-dimensional control surface representing values of modifier variables;

means responsive to said engine speed or period for addressing said memory means for at least one look-up table and selecting a predetermined modifier variable stored therein;

program means responsive to the addressing of said look-up table memory means for interpolating between said addressed predetermined modifier value and adjacent values for computing an optimal modifier value for use in ignition timing calculations, said program means further including means responsive to said engine speed or period and to said computed optimal modifier values for generating an ignition control word indicative of a predetermined delay interval, said ignition timing being controlled thereby such that said ignition control pulse is initiated at the end of a delay represented by said ignition control word, said program means being further effective for terminating said ignition control pulse after a second predetermined period, thereby controlling the ignition timing of said engine.

5. In an internal combustion engine having an intake system, an exhaust system, an engine block, a plurality of engine cylinders disposed in said engine block, a piston disposed for a reciprocal movement within each of said plurality of cylinders, an output shaft responsive to the reciprocal movement of said pistons within said cylinders in response to the combustion fuel and air therein for drivably rotating same, means for controllably supplying fuel to a selected one or more of said cylinders, sensor means associated with one or more of said pistons or said output shaft for generating engine position pulses indicative of the piston having attained a predetermined position such as top-dead-center or the like, said engine position pulse being generally indicative of engine speed or period, and a microprocessor-based engine control system including a memory means, a means responsive to an ignition control pulse for controlling the ignition of said fuel within said cylinders, the improvement comprising:

memory means for storing data representative of at least one look-up table containing a predetermined finite number of modifier values stored in said memory means for establishing a predetermined at least two dimensional control surface representing an infinite number of modifier values which are a function of at least engine speed or period;

means responsive to at least said engine position pulses or a speed or period value derived therefrom for addressing said look-up table to select one of said finite modifier values therefrom;

program means for interpolating between said one selected modifier value and the addressable values adjacent thereto for computing an optimal modifier value, said program means further including means responsive at last to said accurately computed optimal modifier value for calculating a first digital ignition control word indicative of the pulse-width or duration of said ignition control pulse, said program means further including means responsive to each of said engine position pulses for initiating the start of said ignition control pulse upon receipt thereof for controlling both ignition timing and ignition dwell time.

6. In an internal combustion engine having an engine block, a plurality of cylinders disposed in said engine block, a piston disposed in each of said cylinders and mounted for reciprocal movement in response to the combustion of air and fuel in said cylinder, an output shaft responsive to the reciprocation of said pistons within said cylinders for drivably rotating same, means for selectively controlling the supply of fuel to one or more of said plurality of cylinders, means for generating an ignition pulse for controlling the ignition timing and ignition dwell time and therefore the ignition of said fuel within said cylinders, and a microprocessor-based engine control system for controlling the generation of said ignition pulse, said engine control system further comprising:

sensor means operatively associated with said engine for generating an engine position pulse each time one of said pistons is near the top-dead-center position of its associated cylinder;

program means for computing a first digital ignition control word indicative of ignition delay time and a second digital ignition control word indicative of ignition pulse-width;

means responsive to said first and second digital ignition control words for electronically controlling the generation of said ignition control pulse for ignition timing purposes during normal engine operation; and

means for detecting an engine cranking mode of operation for automatically switching the ignition timing from the control of said microprocessor-based engine control system and generating a first command signal; and

means responsive to said first command signal for mechanically controlling the generation of said ignition control pulse and therefore ignition timing throughout said cranking mode of operation.

7. The microprocessor-based engine control system of claim 6 wherein said means for detecting an engine cranking mode of operation includes gate means for directing said engine position pulse to the means for generating an ignition pulse and bypassing the microprocessor, and said means for mechanically controlling includes positioning said sensor means relative to said engine to achieve substantially optimum ignition during cranking.

8. A microprocessor-based engine control system for use in an internal combustion engine having means responsive to fuel control commands for supplying a controlled quantity of fuel to said engine, said engine control system comprising means for sensing one or more engine operating parameters and generating a primary fuel command in response thereto, means for monitoring at least one of said engine operating parameters for detecting a need for acceleration enrichment and generating an acceleration enrichment command in response thereto and means responsive to said acceleration enrichment command for generating first an immediate acceleration enrichment fuel command signal and therefore a longer term programmed increase in said primary fuel command for effecting the desired acceleration enrichment.

9. The microprocessor-based engine control system of claim 8 wherein said means for monitoring includes means for detecting when the engine is in the acceleration mode including detecting the rate of change of movement of the fuel control commands, means for generating a trigger signal to the microprocessor indicative of said acceleration mode, and said last named means includes means for deriving an enrichment factor signal in response to said trigger signal.

10. A microprocessor based engine control system for use in internal combustion engines wherein fuel control commands are used to control the quantity of fuel supplied to the engine, said engine control system comprising a microprocessor, a memory means associated with said microprocessor, program means stored in said memory for controlling said microprocessor to implement a particular fuel control law including data representing a look-up table of modifier values which are a function of engine temperature stored in said memory means, means for measuring engine temperature and addressing said memory means look-up table to obtain one of a finite number of pre-programmed modifier values therefrom, means for interpolating between said addressed one of a finite number of stored modifier values and adjacent stored values for computing an accurate engine temperature modifier value, said program means being responsive to said computed engine temperature modifier value in implementing said fuel control law for generating a highly precise engine temperature-compensated fuel control demand.

11. A microprocessor-based engine control system wherein fuel is supplied to one or more cylinders of an engine and the ignition of said fuel therein is controlled, said engine control system comprising a microprocessor, a memory means associated with said microprocessor a look-up table of modifier values stored in said memory means, means for sensing engine speed and generating a data word indicative thereof, means responsive to said data word for addressing said memory means look-up table and obtaining an addressed modifier value, means for interpolating between said addressed modifier value and adjacent stored values computing an accurate ignition dwell time modifier, and program means stored in said memory means for operating said microprocessor, said program means being responsive to one or more engine operating parameters and to said ignition dwell time modifier value for computing an ignition pulse-width digital word, and means responsive to said digital word for controlling the ignition dwell time of said system.

12. A microprocessor-based engine control system for use in an internal combustion engine of the type having means for supplying a controlled quantity of fuel to the engine in response to a fuel control signal, means for igniting the fuel supplied to the engine in response to an ignition control signal, and means for controlling the recirculation of exhaust gases from the exhaust manifold of said engine back to the intake manifold in response to an EGR control signal, said microprocessor-based engine control system comprising:

means for sensing a plurality of engine operating parameters such as manifold absolute pressure, air temperature, engine coolant temperature, throttle position, EGR valve position, the concentration of oxygen in the exhaust system of said engine and the like and for generating a conditioned output signal indicative thereof;

analog-to-digital converter means including means for converting each of said conditioned sensor output signals into a corresponding DC voltage level;

a microprocessor system including memory means and program means for implementing various control laws, arithematic functions and the like and for generating various sets of computer control signals;

multiplexer means responsive to first computer control signals for selecting a predetermined one of said DC voltage levels;

pulse-width to binary converter means responsive to said selected one of said DC voltage levels for generating a pulse-width indicative of said selected level and converting same into a binary number indicative thereof, said pulse-width to binary converter means being responsive to second computer control signals for transmitting said binary number to said microprocessor system;

means responsive to the speed or period of said engine for generating various engine pulse position signals indicative thereof;

program means within said multiprocessor for utilizing said received binary words to calculate digital control words in accordance with pre-programmed look-up tables, control laws, and data supplied thereto;

a plurality of serial shift registers associated with predetermined control functions;

parallel to serial converter means responsive to third computer control signals for receiving said digital control word in parallel from said microprocessor and serially transferring said control word into a selected one of said shift registers;

means for detecting a plurality of system conditions and generating interrupt signals in response thereto, said interrupt signals being transmitted to said microprocessor unit for use therein;

means associated with said serial shift registers for converting said binary values stored therein into a pulse-width output signal; and

means responsive to predetermined ones of said pulse width output signals for generating said fuel control pulse, said ignition control pulse and said EGR control pulse for controlling the operation of the said internal combustion engine.

13. In an engine system having an internal combustion engine, a plurality of cylinders in said internal combustion engine, a piston mounted for reciprocal motion within each of said plurality of cylinders in response to the combustion of fuel therein, an output shaft operatively coupled to said piston and rotatably driven by the reciprocation of said pistons within said cylinders, at least one fuel injector means responsive to a fuel control pulse for injecting a controlled quantity of fuel into a selected one or more of said plurality of cylinders for combustion therein, at least one ignition means responsive to an ignition control signal for selectively controlling the timing and duration of ignition of said injected fuel within said cylinder, an improved electronic engine control system comprising:

computer means;

memory means operatively coupled to said computer means for storing data representative of a plurality of look-up tables representing multi-dimensional control surfaces of modifier values which are functions of at least one engine operating parameter;

first program data means stored in said memory means for implementing a predetermined fuel control law when executed by said computer means;

means for sensing a plurality of real time engine operating parameters, at least one of said engine operating parameters being a function of engine speed, and for generating digital words indicative of the actual measured value of said sensed engine operating parameter;

means for generating command signals for processing data in said computer;

second program means executable by said computer means in response to said command signals for utilizing said digital words indicative of the actual measured value of said sensed engine operating parameter for addressing said memory means for a predetermined value stored in said look-up table in said memory means and for interpolating between said predetermined stored value and addressable stored values adjacent thereto to compute an interpolated control surface value for use in executing said fuel control law to generate a compensated fuel control digital command; and

means responsive to said fuel control digital command for generating said fuel control pulse to operate said at least one fuel injector means, the duration of said fuel control pulse determining the specific quantity of fuel to be injected into said selected one or more of said plurality of cylinders.

14. The system of claim 13 wherein said means responsive to said fuel control digital command for generating said fuel control pulse includes two separate and distinct circuit means for generating first and second separate non-overlapping, electrical pulses, the initiation of said second electrical pulse being coincident with the end of said first electrical pulse to produce a single uninterrupted fuel control pulse.

15. The system of claim 13 wherein said sensing means includes means for sensing engine temperature and generating a first digital word indicative thereof, means for sensing manifold absolute pressure and generating a second digital word representative thereof, said plurality of look-up tables stored in said memory means including at least one look-up table representing a multi- dimensional control surface of temperature modifier values for use in more accurately implementing said fuel control law, said at least one look-up table of temperature modifier values being a function of engine temperature and manifold absolute pressure and being addressable by said first and second digital words such that said second program means is executed by said computer means for interpolating between the control surface comprising said temperature modifier values for calculating an optimal temperature modifier value corresponding to said actual readings of temperature and manifold absolute pressure, said computer means executing said first program means and utilizing said optimal temperature modifier value in implementing said pre-programmed fuel control law for more accurately computing a compensated value for said fuel control digital command.

16. The system of claim 13 further including means responsive to at least one of said real time sensed engine operating parameters for anticipating a need for acceleration enrichment and generating an acceleration enrichment command signal indicative thereof, said computer means being responsive to said acceleration enrichment command signal for implementing said first program means to compute (1) a first initial and immediate one-time special fuel control digital command for immediate acceleration enrichment purposes and then (2) a longer time, more gradual programmed increase in said fuel control digital command computed by said first program means as it implements said fuel control law under the direction of said computer means.

17. The system of claim 16 wherein said means responsive to said fuel control digital command for generating said fuel control pulse includes a single circuit means for generating the total fuel control pulse from both said first initial and immediate one-time special acceleration enrichment fuel control digital command and from said second longer time, more gradual programmed increase in said normally generated fuel control digital command.

18. In an engine system having an internal combustion engine, a plurality of cylinders in said internal combustion engine, a piston mounted for reciprocal motion within each of said plurality of cylinders in response to the combustion of fuel therein, an output shaft operatively coupled to said piston and rotatably driven by the reciprocation of said pistons within said cylinders, at least one fuel injector means responsive to a fuel control pulse for injecting a controlled quantity of fuel into a selected one or more of said plurality of cylinders for combustion therein, at least one ignition means responsive to an ignition control signal for selectively controlling the timing and duration of ignition of said injected fuel within said cylinder, an improved electronic engine control system comprising:

computer means;

memory means operatively coupled to said computer means for storing data representative of a plurality of look-up tables representing multi-dimensional control surfaces of modifier values which are a function of at least one engine operating parameter;

program means stored in said memory means for implementing a predetermined ignition control signal calculation when executed by said computer means;

means for sensing a plurality of real time engine operating parameters at least one of which is a function of degrees of engine revolution for establishing a reference position for piston whose associated cylinder is to have the injected fuel ignited therein and for generating a reference position pulse indicative thereof;

means for generating command signals for processing data in said computer means;

said computer means executing said program means in response to said command signals for computing a first digital word indicative of a calculated delay time from the receipt of said reference pulse until ignition is to occur and a second separate and distinct digital word indicative of the duration of ignition of said fuel injected into said cylinder.

19. The system of claim 18 wherein said means for generating said ignition control signal further includes means responsive to the occurrence of the next successive reference pulse for generating said ignition control signal even if said predetermined delay period from the receipt of said previous reference position pulse has not yet elapsed to enable smoother acceleration and the like.

20. The system of claim 18 wherein said means for generating said ignition control signal further includes means for initiating said ignition control pulse upon the occurrence of each successive reference position pulse whenever said engine is in a cranking mode of operation such as during warm-up or the like.

21. In combination with an internal combustion engine of the type having an engine block, a plurality of cylinders located in said engine block, a plurality of pistons each mounted in a respective cylinder for reciprocating movement therein, an output shaft operatively coupled to said plurality of pistons and rotatable upon the reciprocation of each of said pistons within said cylinders, an intake manifold common to all of said plurality of cylinders, said intake manifold having an opening therein for receiving air and means disposed within said opening for selectively varying the effective size of said opening, means for supplying fuel to a selected one or more of said plurality of engine cylinders, said fuel supply means including a fuel pump and at least one electromagnetically operated fuel injector valve adapted to operate in response to a fuel control signal, means for igniting the fuel supplied to said selected one or more of said plurality of engine cylinders, said fuel igniting means being responsive to an ignition control signal for controlling the timing and duration of admission of the fuel injected into said selected one or more of said plurality of engine cylinders, and an electrical system for controlling the operation of said fuel supply means and said igniter means to cause the combustion of fuel and air in each of said plurality of engine cylinders and thereby cause said pistons to reciprocate within said cylinders to rotate said output shaft, the improvement in said electrical system comprising:

means for sensing various engine operating parameters on a real time basis and for producing a corresponding plurality of digital signals indicative thereof, at least one of said digital signals representing operator-commanded changes in the size of said opening in said manifold intake;

means for generating said fuel control signal for controlling the operation of said fuel supply means in response to said plurality of digital signals, said fuel control signal generated means including means for receiving and processing said plurality of digital signals from said sensing means, said processing means including a digital data processor operating under the control of a program to convert said plurality of digital signals into a first electrical control signal for operating said fuel pump and controlling the supply of fuel to said fuel injection means, a second electrical control signal for opening said fuel injector valve for a predetermined time interval T1 for a given predetermined revolution of said output crankshaft, means responsive to said one of said digital signals representing a change in the effective size of said opening for anticipating an operator-commanded acceleration enrichment request and generating a fourth electrical control signal indicative thereof, a fourth electrical control signal responsive to said third electrical control signal for opening said fuel injector valve for at least one additional time interval T2 for each predetermined revolution period of said output shaft to increase the amount of fuel supplied to a selected one or more of said plurality of engine cylinders for acceleration enrichment purposes and then increase the rotational speed of said output shaft, another of said plurality of digital signals being representative of a sensed engine operating parameter indicative of one or more of said pistons having reached a predetermined reference position for generating successive engine position pulses, means responsive to the receipt of an engine position pulse for counting a delay time therefrom prior to generating said ignition control signal and causing the combustion of injected fuel within said selected one or more of said plurality of said cylinders, and means normally responsive to the end of said predetermined delay time interval for generating said ignition control pulse for a time interval T3 whose duration controls the time of combustion of said injected fuel within said selected engine cylinder.

22. The system of claim 21 wherein said means normally responsive to the termination of said predetermined delay count for automatically initiating the generation of said ignition control pulse upon the occurrence of the next successive engine position pulse regardless of the state of said delay counter whenever acceleration has been requested, the engine is in the cranking mode of operation, and the like.