Input/output electronic for microprocessor-based engine control system

• US 4,242,728 A
• Filed: 02/27/1978
• Issued: 12/30/1980
• 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: Hartford, Thomas W.
• Primary Examiner(s): Gruber, Felix D.
• Application Number:
  US05/881,323
• Time in Patent Office: 1,037 Days
• Field of Search: 364/424, 364/431, 364/442, 123/32 EB, 123/32 EH, 123/119 A, 235/92 T, 235/92 SH, 340/347 AD, 340/347 CC
• US Class Current: 701/112
• CPC Class Codes: F02D 41/0047 Controlling exhaust gas recirculation [EGR] temperature control with cooler in recirculation circuit F02M26/33
• 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: 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 relating to one or more actual engine operating parameters such as manifold absolute pressure, throttle position, engine coolant temperature, air temperature, engine speed or period or 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 system computes one or more digital words indicative of particular computer-commanded engine control operations and output circuitry responds to predetermined computer-generated commands and to the computed digital command words for generating corresponding pulse-width control signals for controlling such engine operations as fuel-injection, ignition timing, proportional and/or on-off EGR control, and the like. A fuel management control "limp home" circuit is also disclosed which will allow a vehicle to be driven for a short distance such as to a repair station or the like whenever the microprocessor-controlled fuel injection system fails to function properly.

Claims

1. A microprocessor-based electronic engine control system responsive to one or more engine-operating parameters for generating one or more control commands for operating such engine functions as fuel injection, ignition timing, and proportional EGR control, said system including an engine having an intake system, an exhaust system, conduit means for operatively connecting said exhaust system to said intake system for recirculating exhaust gases back to said intake system to modify the air-fuel ratios existing therein, an EGR valve disposed at least partially within said conduit means and responsive to an EGR control signal for selectively increasing and decreasing the quantity of exhaust gases recirculated back to said intake system, said electronic engine control system further including a microprocessor, memory means operatively associated with said microprocessor, means for sensing the actual relative position of said EGR valve and generating a digital word indicative thereof, the improvement comprising memory means storing data representative of a look-up table of modifier values which are a function of at least EGR valve positions stored in said memory means and addressable by said digital word, program storage means implemented by said microprocessor and responsive to sensed engine-operating parameters for calculating a desired EGR valve position and generating a computer-calculated EGR command indicative thereof, means responsive to said EGR command for generating a count indicative thereof and counter means for initially storing said count and decrementing same to produce an EGR pulse-width output signal in response thereto for selectively re-positioning said EGR valve.

2. In a microprocessor-based engine control system including a microprocessor means, memory means for storing a program for implementing at least one control law, said microprocessor being responsive to one or more engine operating parameters for normally generating fuel injection commands, the improvement comprising:

means for detecting a failure in said system and for generating a signal indicative thereof;

means responsive to said failure indicative signal for generating a series of limp home fuel control pulses sufficient to enable the vehicle to travel a short distance for repairs;

said means for generating said series of "limp home" fuel control pulses includes one-shot multivibrator means responsive to the generation of each of said engine position pulses for generating a corresponding "limp home" fuel control pulse, RC circuit means operatively coupled to said one-shot multivibrator means for determining the pulse duration of said "limp home" fuel control pulses, and pulse transmission gating means coupled to the output of said one-shot multivibrator means for receiving said "limp home" fuel control pulses whose generation is triggered by the generation of said engine position pulses, said transmission pulse gating means normally preventing said fuel injection means from receiving said "limp home" fuel control pulses but being responsive to the presence of said "fail" signal for passing said "limp home" fuel control pulses to said fuel injection means and enabling said "limp home" pulses to control the injection of fuel into said engine in spite of a failure in some portion of said microprocessor-based engine control system which might affect the reliability of said normally-generated fuel injection commands.

3. In an internal combustion engine system 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 of fuel 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 one or more pistons having attained a predetermined reference position, said engine position pulses being generally indicative of engine speed or period, and a computer-based engine control system including computer means, memory means operatively associated with said computer means, program storage means stored within said memory means for implementing at least one fuel control law, sensor means associated with said engine for measuring a plurality of engine-operating values and generating digital words indicative of said measured values, the improvement comprising means storing at least one multi-dimensional control surface of modifier values stored in said memory means, said computer means being responsive to said program storage means for utilizing at least one of said digital words to address said memory means and interpolate between the stored values of said at least one multi-dimensional control surface to compute a modifier value functionally related to the measured value of the engine-operating parameter represented by said at least one of said digital words and for implementing said at least one fuel control law utilizing at least one of the computed modifier values for generating a fuel control command, means responsive to said fuel control commands for outputting computer-calculated fuel control pulses, said means for controllably supplying fuel to a selected one or more of said cylinders being normally responsive to said computer-calculated fuel control pulses for controlling the time and quantity of fuel supplied to said selected one or more of said cylinders, means for monitoring the normal operation of said computer means and said program means and generating a "fail" signal whenever the reliability of one or more computer-generated fuel control commands could be unreliable, means responsive to the generation of said engine position pulses for generating secondary fuel control pulses, and means responsive to the generation of said "fail" signal for terminating the control of the operation of said fuel supplying means by said computer-calculated fuel control pulses but continuing the operation of said fuel supplying means under the control of said secondary fuel control pulses so that the operation of said internal combustion engine, while degraded, is not terminated or controlled by unreliable or unsafe system commands.

4. The system of claim 3 wherein said means for generating said secondary fuel control pulses includes means for generating a single pulse for an input pulse.

5. The system of claim 4 wherein said means for generating said secondary fuel control pulses includes timing circuit means operatively coupled to said single pulse generating means for selectively controlling the pulse duration of said secondary fuel control pulses.

6. The system of claim 4 wherein said means responsive to said "fail" signal includes means normally blocking said secondary fuel control pulses but responsive to said "fail" signal for passing said secondary fuel control pulses to said fuel supplying means.

7. 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 for reciprocal movement in 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 of fuel therein for drivably rotating said output shaft, a plurality of individual sensor means associated with various portions of said engine for sensing various separate and distinct engine operating parameters such as manifold pressure, throttle position, coolant temperature, air temperature, engine speed or period, and for outputting corresponding pulse-width signals whose duration times are indicative of the measured value of said sensed parameters, signal conversion means for selectively converting a predetermined one of said pulse-width signals into a multi-bit digital word indicative thereof, computer means, memory means operatively associated with said computer means, program storage means within said memory means for execution by said computer means for implementing at least one programmed control law utilizing said multi-bit digital word indicative of the value of one of said measured engine-operating values and generating an output control command, and means responsive to said output control command for controlling at least one aspect of the operation of said internal combustion engine, the improvement wherein said program storage means includes means responsive to the execution thereof by said computer means for generating certain computer command signals, said plurality of individual sensor means being responsive to at least one of said computer command signals for initiating the conversion of measured values of engine-operating parameters into equivalent corresponding pulse-width signals and said signal conversion means being responsive to others of said certain computer command signals for programmably selecting which one of said pulse-width signals are to be converted into a multi-bit digital word at a predetermined time.

8. The engine system of claim 7 wherein said computer means samples said sensor means and is responsive to said program storage means for selectively varying the frequency of sampling of each of said individual sensor means.

9. The engine system of claim 8 wherein said signal conversion means includes a single means for both performing said pulse-width-to-binary number conversion and for temporarily storing the resulting binary number until it is sampled by said computer means thereby eliminating the need for a separate and distinct holding register.

10. 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 therein for drivably rotating said output shaft, fuel injector means responsive to a fuel control pulse for selectively injecting a predetermined controlled quantity of fuel into one or more of said plurality of cylinders;

electrically operated fuel pump means for normally supplying fuel to said fuel injector means, means responsive to an ignition control signal for controlling the ignition of said injected fuel, means for detecting a predetermined reference position of said output shaft and for generating successive periodic output shaft position pulses in response thereto, means for sensing a plurality of other engine-operating parameters such as manifold absolute pressure, throttle position, coolant temperature, air temperature, engine speed or period, or the like and for generating a sensor output signal indicative of the actual value thereof, means for converting a selected one of said sensor output signals into a digital word indicative of the value of the corresponding sensed engine-operating parameter, an improved computer-based electronic engine control system including computer means, memory means, program control means for implementing at least a predetermined fuel control law to generate a digital fuel control command signal, and means responsive to said digital fuel control command signal for controlling the time of initiation and pulse-width of said fuel control pulse for selectively operating said fuel injector means to precisely control the quantity of fuel injected into said selected one or more of said plurality of cylinders and the initiation time thereof, counter means responsive to said successively generated periodic output shaft position pulses for measuring the elapsed time therebetween, said counter means including a serial dynamic shift register and half-adder circuit means operatively coupled together for performing a binary computer-type operation while reducing the size of the surface area utilized, the cost and the required power when said counter means is implemented in an integrated circuit, control logic means coupled to at least some of the outputs of said serial dynamic shift register, said control logic means being responsive to said counter means having attained its maximum count value for enabling said half adder circuit means to terminate further incrementing of said counter means, a latching register for storing the contents of said serial dynamic shift register, means for transferring the count attained in said serial dynamic storage register into said latching register and for clearing and restarting said counter means with each successive periodic output shaft position pulse,

means for detecting a serial overflow in said serial dynamic shift register for indicating an engine stall condition, and means responsive to the detection of said engine stall condition for turning off said electrically operated fuel pump means.