Closed loop engine control system

Claim 2

An internal combustion engine control system for modulating an engine operating parameter substantially independently of environmentally induced sensor output variations, said control system comprising: sensor means for examining an engine operating variable operative to generate a sensor means signal having an environmentally variable characteristic selected to be indicative of a quality of the combustion process occurring within the engine said variable characteristic being subject to environmentally induced variations; comparator means responsive to the sensor means signal operative to generate a comparator means output signal having a predetermined constant level signal established when said combustion process quality is one of a greater or lesser quality than a predetermined quality; integrator means receiving said comparator output signal operative to integrate said predetermined constant signal level to generate a gradually changing output signal changing in one of two change directions at a predetermined integrating rate as long as said predetermined constant level signal is established; and fuel delivery controller means receiving said gradually changing output signal and operative to modulate fuel delivery in response thereto; whereby said predetermined constant level signal and said predetermined integrating rate cause said fuel delivery modulation to be substantially independent of said environmentally induced variations in said sensor characteristic.

Claim 3

The system as claimed in claim 1 wherein said sensor means signal variable characteristic varies with air/fuel ratio and comprises a transitional band portion intermediate a relatively high strength signal and a relatively low strength signal, said transitional band portion being constant with variations in said high and low strength signals induced by variations of at least one environmental condition; and occurring substantially at a selected air/fuel ratio; wherein said system comprises reference level establishing means operative to provide said comparator means with a set point level within said sensor transitional band portion indicative of said predetermined quality; wherein said comparator means output signal comprises a second constant signal level different from said predetermined constant level signal, said second constant level signal being established as long as said quality deviation is the other of said greater and lesser qualities; wherein said integrator means integrates said second constant signal level to gradually change said gradually changing signal level in the other of said two changes directions at said predetermined integrating rates; and wherein said fuel delivery controller means modulates fuel delivery so as to gradually increase the air/fuel ratio when said comparator output signal is established at one of said predetermined and second constant levels signals and to otherwise gradually decrease said air/fuel ratio when said comparator output signal is established at the other of said predetermined and second constant levels signals; whereby said predetermined integrating rate and the difference between said predetermined and second constant signal levels causes said fuel delivery controller to vary the air/fuel ratio about said selected air/fuel ratio within a range of air/fuel ratios substantially independent of said variation of said at least one environmental condition.

Claim 4

The system as claimed in claim 1 wherein said fuel delivery controller means comprises at least one timing capacitor and current source means controllable to selectively charge said timing capacitor at a controllable rate from an initial value determined in accordance with a second engine operating variable to a threshold value determine in accordance with a third engine operating variable, said controllable rate being varied in accordance with said gradually changing output signal to controllaBly modulate the quantities of fuel delivered to the associated engine independently of variations in fuel delivery commanded to accommodate changes in said second and third operating variables.

Claim 5

The system as claimed in claim 1 wherein said integrator measn comprises an operational amplifier having an input terminal and an output terminal and an integrating capacitor coupling said input terminal and output terminal and determining asid predetermined integrating rate.

Claim 6

The system as claimed in claim 2 wherein said relatively high strength signal level comprises a minimum high strength signal level and said relatively low strength sensor signal level comprises a maximum low strength signal level, said minimum high strength signal level and said maximum low strength signal level each varying with the temperature and aging characteristics of said sensor means and the difference between minimum high strength and maximum lower strength signal levels defining said constant transitional band so as to be substantially independent of the aging and temperature characteristics of said sensor means so that the fuel delivery controller means modulates fuel delivery substantially independent of the aging and temperature characteristics of said sensor means.

Claim 7

The system as claimed in claim 4 wherein said comparator means comprises an operational amplifier having an input terminal and an output terminal coupled by parallelly connected oppositely polled semiconductor current conducting devices each having a predetermined voltage drop when conducting, said predetermined voltage drops establishing the magnitude of said constant signal levels and permitting said comparator means to switch substantially instantaneously from one of said constant signal levels to the other when said sensor means signal passes through said set point level so that the range in which said sensor means signal varies about said set point level is determined substantially by said magnitudes of said constant signal levels and said predetermined rate at which said integrator means integrates said comparator output signals.

Claim 8

An internal combustion engine controlling an engine parameter varying with operating conditions of an internal combustion engine, said control system comprising: a. sensor means operatively connected with said engine to provide a sensor means signal having a range of values varying with said engine parameter; b. reference level establishing means for providing a set point level within said range of said sensor means signal; c. comparator means connected to receive said sensor means signal and said set point level operative to establish one of a constant positive and negative polarity comparator output signal when said sensor means signal is greater than said set point level and to establish the other of said constant positive and negative polarity comparator output signals when said sensor means signal is less than said set point level; d. integrator means operatively connected with said comparator means to generate a control signal having a magnitude changing with the integral of said constant positive polarity comparator output signal when said constant positive polarity comparator output signal is established and with the integral of said constant negative polarity comparator output signal when said constant negative polarity comparator output signal is established; and e. control means operatively connecting said integrator means and said engine for controlling said engine to vary said engine parameter in accordance with said control signal, whereby the integration of said constant positive and negative polarity comparator output signals causes said control signal to control said engine so as to vary said engine parameter so that said sensor means signal is alternately increased and decreased through said set point level.

Claim 9

An internal combustion engine controlling an engine parameter varying with operating conditions of an internal combustion engine, said control system comprising: a. sensor means operatively connected with said engine to provide a sensor means signal having a range of values varying with said engine parameter; b. reference level establishing means for providing a set point level within said range of said sensor means signal; c. comparator means connected to receive said sensor means signal and said set point level operative to establish one of a constant positive and negative polarity comparator output signal when said sensor means signal is greater than said set point level and to establish the other of said constant positive and negative polarity comparator output signals when said sensor means signal is less than said set point level; d. integrator means operatively connected with said comparator means to generate a control signal having a magnitude changing with the integral of said constant positive polarity comparator output signal when said constant positive polarity comparator output signal is established and with the integral of said constant negative polarity comparator output signal when said constant negative polarity comparator output signal is established; and e. control means operatively connecting said integrator means and said engine for controlling said engine to vary said engine parameter in accordance with said control signal, whereby the integration of said constant positive and negative polarity comparator output signals causes said control signal to control said engine so as to vary said engine parameter so that said sensor means signal is alternately increased and decreased through said set point level.

Claim 10

The engine control system of claim 7 wherein said comparator means comprises an operational amplifier having An input terminal and an output terminal coupled by parallelly connected oppositely polled semiconductor current conducting devices each having a predetermined voltage drop when conducting, said predetermined voltage drops establishing the magnitudes of said constant output signals and permitting said comparator means to switch substantially instantaneously from one of said constant positive and negative output signals to the other when said sensor means signal passes through said set point level so that said range in which said sensor means signal varies about said set point level is determined substantially by said magnitudes of said constant positive and negative polarity comparator output signals and the rate at which said integrator means integrates said comparator output signals.

Claim 11

The apparatus of claim 8 wherein said semiconductor devices comprise forward drops of said unidirectional current conducting devices having nominal forward voltage drops establishing said constant output signals.

Claim 12

The apparatus of claim 7 wherein said control means comprises an operator controllable air/fuel delivery means for delivering controllable air/fuel mixture to the engine, said control means operative to control one of said air and fuel so as to vary the air/fuel ratio in a predetermined range about a selected air/fuel ratio.

Claim 13

An internal combustion engine control system for modulating an engine operating parameter substantially independently of environmentally induced sensor output variations, said control system comprising: sensor means for examining an engine operating variable operative to generate a sensor means signal having an environmentally variable characteristic selected to be indicative of a quality of the combustion process occurring within the engine said variable characteristic being subject to environmentally induced variations; reference level establishing means for generating a set point level having a value in the range of values of said sensor means signal; comparator means connected to said sensor means and said reference level establishing means operative to provide a comparator signal having first and second constant magnitudes when said sensor means signal is respectively above and below said set point level; integrator means operatively connected with said comparator means operative to generate a control signal having a magnitude changing at a first predetermined integrating rate when the magnitude of said comparator signal is one of said first and second constant magnitudes and a second predetermined integrating rate when the magnitude of said comparison signal is the other of said first and second constant magnitudes; fuel delivery controller means receiving said gradually changing output signal and operative to modulate fuel delivery in response thereto; whereby said first and second constant levels and said predetermined integrating rate cause said fuel delivery modulation to be substantially independent of said environmentally induced variations in said sensor characteristic.

Claim 14

An internal combustion engine control system for modulating an engine operating parameter substantially independently of environmentally induced sensor output variations, said control system comprising: sensor means for examining an engine operating variable operative to generate a sensor means signal having an environmentally variable characteristic selected to be indicative of a quality of the combustion process occurring within the engine said variable characteristic being subject to environmentally induced variations; reference level establishing means for generating a set point level having a value in the range of values of said sensor means signal; comparator means connected to said sensor means and said reference level establishing means operative to provide a comparator signal having first and second constant magnitudes when said sensor means signal is respectively above and below said set point level; integrator means operatively connected with said comparator means operative to generate a control signal having a magnitude changing at a first predetermined integrating rate when the magnitude of said comparator signal is one of said first and second constant magnitudes and a second predetermined integrating rate when the magnitude of said comparison signal is the other of said first and second constant magnitudes; fuel delivery controller means receiving said gradually changing output signal and operative to modulate fuel delivery in response thereto; whereby said first and second constant levels and said predetermined integrating rate cause said fuel delivery modulation to be substantially independent of said environmentally induced variations in said sensor characteristic.