Sri Kalahasteeswara Inst. of Technology.
A method and apparatus for controlling the various functions of an internal combustion engine using a program-controlled microprocessor having a memory pre-programmed with various control laws and associated control schedules receives information concerning one or more engine-operating parameters such as manifold absolute pressure, throttle position, engine coolant temperature, air temperature, and engine speed or period or the like. These parameters are sensed and then supplied to input circuit for signal conditioning and conversion into digital words usable by the microprocessor. The micro processor system computers one or more digital command word indicative of a computer-commanded engine control operation and output circuitry responds to predetermined computer-generated commands and to corresponding pulse with control signals for controlling such engine operations as fuel injection, ignition timing, proportional and /or on-off EGR control and the like.
More particularly this disclosure relates to an improved microprocessor-based engine control system for controlling both fuel and ignition wherein an exhaust gas sensor is periodically sampled for the integrity of its output signals. In addition , an A/D converter having a novel window which is used in engine control system and the digital control of ignition signals is also described.
1. A multiprocessing microprocessor based fuel injection system for an internal combustion engine comprising:
power supply receiving means adapted to receive power upon demand of the engine operator and to receive standby voltage during engine non-operating times;
a plurality of sensors adapted to be mounted on the engine, each of said sensors providing an output electrical signal representing one of a plurality of engine operating conditions;
A/D converter means for converting said output signals from said sensors into digitally equivalent signals;
injector means mounted on the engine upstream of the intake valves of the engine;
fuel supply means including a fuel pump adapted to supply fuel to said injector means;
programmable read only memory (PROM) means for storing control law constants and data signals representative of predetermined engine calibrations unique to the engine, and
a first and second microprocessor having storage means therein, said first microprocessor having a master control program stored in its storage means and receiving input signals from said programmable read only memory means and both of saidmicroprocessors electrically connected together in a multiprocessing configuration for shared computational operation according to input signals provided by said sensors, said programmable read only memory means and predetermined data in said storagemeans for calculating fuel quantity electrical signals to operate said injector means from said first microprocessor and said fuel pump from said second microprocessor.
2. A multiprocessing microprocessor based system according to claim 1 wherein said microprocessors are controlled from a single oscillator means wherein said first microprocessor assumes the master role and synchronizes the operation of said second microprocessor.
3. A multiprocessing microprocessor based system according to claim 1 wherein said programmable read only memory means is operatively connected to at least one of the input-output portsof said first microprocessor and is controlled by a control signal generated in said first microprocessor for transmitting control law constants and data from said programmable read only memory means to said first microprocessor according to said master control program.
4. A multiprocessing...