Method of estimating the fuel/air ratio of an internal combustion engine
First Claim
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1. A method of estimating the ratio of the air and fuel mixture supplied to a cylinder of an internal combustion engine through an intake valve that is closed upon completion of the intake phase of the cylinder to trap an air-fuel charge in the cylinder at a predetermined crank angle during rotation of an output crankshaft of the engine, the intake phase being followed by a compression phase and a combustion phase as the engine crank angle increases, the method comprising the steps of:
- (a) determining the trapped charge mass m in the cylinder;
(b) setting an initial estimated fuel/air ratio value;
(c) for the estimated fuel/air ratio, determining the gas pressure in the cylinder and the engine crank angle corresponding thereto at which the mass fraction burned μ
b during combustion represents substantially complete combustion;
(d) determining the mass burned m'"'"'f based on the pressure and crank angle at which the mass fraction burned μ
b during combustion represented substantially complete combustion;
(e) computing the total fuel mass burned mf during combustion from the value of m'"'"'f ;
(f) estimating the fuel/air ratio of the mixture supplied to the cylinder from the values of m and mf ; and
(g) repeating steps (c) through (f) for each value of pressure and engine angle stored in the history table until consecutive values of the estimated fuel/air ratio are substantially equal, the last estimated value of the fuel/air ratio being a measure of the fuel/air ratio of the mixture supplied to the cylinder.
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Abstract
A method of estimating the fuel/air ratio of the mixture supplied to an engine is described in which the in-cylinder pressure signal in a combustion cycle is processed to obtain an estimate of the fresh mixture strength supplied to the cylinder. The estimation is obtained by calculating the trapped charge mass and the total fuel mass consumed in a combustion cycle. Based on these values, the fuel/air ratio is estimated.
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Citations
3 Claims
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1. A method of estimating the ratio of the air and fuel mixture supplied to a cylinder of an internal combustion engine through an intake valve that is closed upon completion of the intake phase of the cylinder to trap an air-fuel charge in the cylinder at a predetermined crank angle during rotation of an output crankshaft of the engine, the intake phase being followed by a compression phase and a combustion phase as the engine crank angle increases, the method comprising the steps of:
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(a) determining the trapped charge mass m in the cylinder; (b) setting an initial estimated fuel/air ratio value; (c) for the estimated fuel/air ratio, determining the gas pressure in the cylinder and the engine crank angle corresponding thereto at which the mass fraction burned μ
b during combustion represents substantially complete combustion;(d) determining the mass burned m'"'"'f based on the pressure and crank angle at which the mass fraction burned μ
b during combustion represented substantially complete combustion;(e) computing the total fuel mass burned mf during combustion from the value of m'"'"'f ; (f) estimating the fuel/air ratio of the mixture supplied to the cylinder from the values of m and mf ; and (g) repeating steps (c) through (f) for each value of pressure and engine angle stored in the history table until consecutive values of the estimated fuel/air ratio are substantially equal, the last estimated value of the fuel/air ratio being a measure of the fuel/air ratio of the mixture supplied to the cylinder.
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2. A method of estimating the ratio of the air and fuel mixture supplied to a cylinder of an internal combustion engine through an intake valve that is closed upon completion of the intake plase of the cylinder to trap an air-fuel charge in the cylinder at a predetermined crank angle during rotation of an output crankshaft of the engine, the intake phase being followed by a compression phase and a combustion phase as the engine crank angle increases, the method comprising the steps of:
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(a) determining the trapped charge mass m in the cylinder; (b) setting an initial estimated fuel/air ratio value; (c) repeatedly sampling and storing in a history table the gas pressure in the cylinder and the engine crank angle corresponding thereto during the combustion phase; (d) for the estimated fuel/air ratio, estimating the instantaneous mass fraction burned μ
b during combustion for each of the sampled gas pressures until the estimated value of μ
b represents substantially complete combustion;(e) determining the mass burned m'"'"'f based on the pressure and crank angle at which μ
b was determined at step (d) to indicate substantially complete combustion;(f) computing the total fuel mass burned mf during combustion from the values of μ
b and m'"'"'f ;(g) estimating the fuel/air ratio of the mixture supplied to the cylinder from the values of m and mf ; and (h) repeating steps (d) through (g) for each value of pressure and engine angle stored in the history table until consecutive values of the estimated fuel/air ratio are substantially equal, the last estimated value of the fuel/air ratio being a measure of the fuel/air ratio of the mixture supplied to the cylinder.
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3. A method of estimating the ratio of the air and fuel mixture supplied to a cylinder of an internal combustion engine through an intake valve that is closed upon completion of the intake phase of the cylinder to trap an air-fuel charge in the cylinder at a predetermined crank angle during rotation of an output crankshaft of the engine, the intake phase being followed by a compression phase and a combustion phase as the engine crank angle increases, the method comprising the steps of:
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(a) determining the trapped charge mass m in the cylinder; (b) setting an initial estimated fuel/air ratio value; (c) repeatedly sampling and storing in a history table the gas pressure in the cylinder and the engine crank angle corresponding thereto during the combustion phase; (d) for the estimated fuel/air ratio, estimating the instantaneous mass fraction burned μ
b during combustion for each of the sampled gas pressures until the estimated value of μ
b represents substantially complete combustion;(e) determining the mass burned m'"'"'f based on the pressure and crank angle at which μ
b was determined at step (d) to indicate substantially complete combustion;(f) computing the total fuel mass burned mf during combustion from the values of μ
b and m'"'"'f ;(g) estimating the temperature To of the trapped charge from the total fuel burned Mf and an average of the estimated fuel/air ratios; (h) redetermining the trapped charge mass m from the estimated temperature To ; (i) estimating the fuel/air ratio of the mixture supplied to the cylinder from the values of m and mf ; and (j) repeating steps (d) through (g) for each value of pressure and engine angle stored in the history table until consecutive values of the estimated fuel/air ratio are substantially equal, the last estimated value of the fuel/air ratio being a measure of the fuel/air ratio of the mixture supplied to the cylinder.
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Specification
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Current AssigneeGeneral Motors Auto OOO (General Motors Company)
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Original AssigneeGeneral Motors Corporation (General Motors Company)
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InventorsJavaherian, Hossein
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Primary Examiner(s)SCHWARTZ, LARRY I
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Application NumberUS06/130,945Time in Patent Office365 DaysField of Search73/116, 73/115, 73/117.3US Class Current73/114.72CPC Class CodesF02D 35/023 by determining the cylinder...F02D 35/026 using an estimationF02D 41/14 Introducing closed-loop cor...F02D 41/1458 with determination means us...G01M 15/08 by monitoring pressure in c...
