Air/fuel ratio control system for internal combustion engine and method therefor
First Claim
1. An air/fuel ratio control system for an internal combustion engine having a plurality of engine cylinders comprising:
- a first detector for detecting engine operating conditions to produce an engine operating condition indicative signal representative of a basic fuel delivery parameter;
a second detector for detecting cycle-to-cycle fluctuations of the output of each of the engine cylinders to produce a detector signal when the engine fluctuation rate is outside of a given allowable range;
a counter means for counting occurrences of the non-allowable engine fluctuations in each engine cylinder and outputting a first counter signal representative of the number of engine cylinders in which non-allowable engine fluctuations are detected; and
a controller unit responsive to said engine operating condition indicative signal for deriving a fuel delivery amount based thereon, and deriving an air/fuel ratio which varies in the direction of a leaner mixture at a first given rate as long as the first counter signal value remains less than a given threshold and in the direction of a richer mixture at a second given rate when the first counter signal value is equal to or greater than said given threshold.
1 Assignment
0 Petitions
Accused Products
Abstract
An air/fuel ratio control system is applicable to lean mixture combustion internal combustion engines. The control system determines the value of the mixture ratio at which engine stability can switch between stable and unstable conditions. As long as the engine continues to run in a stable condition in which the engine roughness is within an acceptable range, the mixture is intermittently leaned out by a given proportion. On the other hand, when engine roughness in an unacceptable range is detected, the mixture ratio is enriched by a given proportion to overcome the unacceptable engine roughness. Enrichment of the mixture is continued until engine roughness within the acceptable range is detected.
-
Citations
55 Claims
-
1. An air/fuel ratio control system for an internal combustion engine having a plurality of engine cylinders comprising:
-
a first detector for detecting engine operating conditions to produce an engine operating condition indicative signal representative of a basic fuel delivery parameter; a second detector for detecting cycle-to-cycle fluctuations of the output of each of the engine cylinders to produce a detector signal when the engine fluctuation rate is outside of a given allowable range; a counter means for counting occurrences of the non-allowable engine fluctuations in each engine cylinder and outputting a first counter signal representative of the number of engine cylinders in which non-allowable engine fluctuations are detected; and a controller unit responsive to said engine operating condition indicative signal for deriving a fuel delivery amount based thereon, and deriving an air/fuel ratio which varies in the direction of a leaner mixture at a first given rate as long as the first counter signal value remains less than a given threshold and in the direction of a richer mixture at a second given rate when the first counter signal value is equal to or greater than said given threshold. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
-
-
13. An air/fuel ratio control system for a multicylinder internal combustion engine having a plurality of engine cylinders with combustion chambers and an induction system for introducing an air/fuel mixture into each of said combustion chamber, which control system comprising:
-
a first detector means for detecting engine operating conditions to produce an engine operating condition indicative signal representative of a basic fuel delivery parameter; a second detector means for detecting engine roughness in each of said engine cylinders during its combustion stroke, and for judging if the detected engine roughness is within a predetermined acceptable range and producing a detector signal when said detected engine roughness is outside of said acceptable range; a counter means for counting the number of cylinders in which unacceptable engine roughness is detected, said counter means producing an enrichment demand signal when said counted number of cylinders becomes greater than a predetermined first threshold; and a controller unit responsive to said engine operating condition indicative signal to derive a fuel delivery amount based thereon, said control unit controlling the air/fuel ratio of an air/fuel mixture to make the mixture leaner at a given first rate and responsive to said enrichment demand signal to enrich the mixture at a given second rate. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27)
-
-
28. A method for controlling an air/fuel ratio for an internal combustion engine comprising the steps of:
-
detecting engine operating conditions to derive a fuel delivery amount depending thereupon; detecting engine roughness in each engine cylinder; judging if the detected engine roughness is within a predetermined acceptable range; counting occurrences of an unacceptable range of engine roughness in each cylinder; comparing the number of the engine cylinders in which unacceptable engine roughness is detected within a given duration with a predetermined first threshold; and - View Dependent Claims (30)
-
- 29. controlling the air/fuel mixture so as to lean out the mixture at a first given rate as long as the number of cylinders is less than said first threshold and to enrich the mixture at a second given rate when said number of cylinder is greater than said first threshold.
-
39. A control method for controlling an air/fuel mixture to be delivered in a multi-cylinder fuel injection internal combustion engine, comprising the steps of:
-
detecting engine revolution speed; detecting the load condition on the engine; detecting the engine crankshaft angular position; detecting the internal pressure in each combustion chamber in each of the engine cylinders; deriving a fuel injection amount based on said engine speed and the engine load to determine a fuel injection pulse width to control the duty cycle of a fuel injection valve in order to inject a controlled amount of fuel into the induction system of the engine; detecting the peak value of the internal pressure in each cylinder and deriving the crankshaft angular position at the peak pressure; comparing the derived crankshaft angular position at the peak pressure with upper and lower thresholds; counting the occurrences of the crankshaft angular position at the peak pressure outside of the range defined by said upper and lower thresholds for each cylinder; and modifying the fuel injection amount by reducing the amount as long as the number of cylinders in which the crankshaft angular position at the peak pressure falls outside of said normal range is less than a given first threshold and the number of occurrences of the crankshaft angular position outside of said normal range in each cylinder is less than a given second threshold, and by increasing the fuel injection amount when the number of cylinders is equal to or greater than said first threshold, or the number of occurrences in each cylinder is equal to or greater than said second threshold.
-
-
46. A fuel supply control method for an internal combustion engine comprising the steps of:
-
measuring a number of engine operating parameters including at least the pressure within the engine combustion chambers; selecting a predetermined basic fuel supply quantity in accordance with the measured operating parameters from a plurality of empirically determined values; deriving a measure of engine roughness from the measured combustion chamber pressure; maintaining a count of the number of occurrences of engine roughness; adjusting the basic fuel supply quantity in accordance with the count of occurrences of engine roughness; and supplying an amount of fuel represented by the adjusted fuel supply quantity to the engine. - View Dependent Claims (48, 53)
-
Specification