Claims
- 1. An air-fuel ratio control apparatus for a gas engine, comprising:
- a mixer for mixing intake air and a fuel gas for supply to a gas engine;
- subsidiary supply means for supplying at least one of the intake air and the fuel gas downstream of said mixer, with said mixer being bypassed;
- oxygen concentration sensors disposed in an exhaust system of said gas engine for detecting a concentration of oxygen in an exhaust gas exhausted from said gas engine;
- means for detecting operating conditions of said gas engine;
- means for setting a basic amount of gas supplied through said subsidiary supply means in accordance with the operating conditions of said gas engine;
- means for setting a correction amount proportional to a total fuel gas supply rate including an amount of fuel gas supplied directly to said mixer and an amount of fuel as supplied through said subsidiary supply means, in accordance with output signals of said operating condition detecting means and output signals of said oxygen concentration sensors; and
- means for setting a control amount of gas supplied through said subsidiary supply means by adding the correction amount to the basic amount.
- 2. An air fuel ratio control apparatus for a gas engine according to claim 1, wherein the operating conditions of said gas engine include intake air pressure and a rotational speed of said gas engine.
- 3. An air-fuel ratio control apparatus for a gas engine according to claim 1, further comprising a catalyzer disposed in the exhaust system of said gas engine for purifying the exhaust gas exhausted from said gas engine, wherein said oxygen concentration sensors include a first oxygen concentration sensor and a second oxygen concentration sensor disposed upstream and downstream, respectively, of said catalyzer.
- 4. An air-fuel ratio control apparatus for a gas engine according to claim 2, further comprising a catalyzer disposed in the exhaust system of said gas engine for purifying the exhaust gas exhausted from said gas engine, wherein said oxygen concentration sensors include a first oxygen concentration sensor and a second oxygen concentration sensor disposed upstream and downstream of said catalyzer, respectively.
- 5. An air-fuel ratio control apparatus for a gas engine according to claim 2, wherein:
- said basic amount setting means includes means for setting the basic amount (DB), based on the intake air pressure (PM) and the rotational speed (NE) of said gas engine, in accordance with the following equation,
- DB.rarw.(PM-PMOS).times.KPMB.times.KNE.times.KDB+DOS
- where PMOS is a constant corresponding to an offset value of the intake air pressure (PM) in the total fuel gas supply rate versus the intake air pressure (PM) characteristic curve; KPMB is a transform coefficient which is used to transform a value of the intake air pressure (PM) into a duty ratio; KNE is a rotational speed correction coefficient corresponding to the rotational speed (NE) of said gas engine; KDB is a correction coefficient which is set corresponding to values of the intake air pressure (PM) and the rotational speed (NE) of said gas engine; and DOS is a constant corresponding to an offset value of the duty ratio in the subsidiary fuel gas supply rate through said subsidiary supply means versus the duty ratio characteristic curve,
- said correction amount setting means is constructed to calculate and set the correction amount (DF), based on the intake air pressure (PM), the rotational speed (NE) of said gas engine, and an air-fuel ratio correction coefficient (FAF), and in accordance with the following equation,
- DF.rarw.(PM-PMOS).times.KPMF.times.KNE.times.FAF
- where KPMF is obtained in accordance with the equation KPMF.rarw..alpha./.beta., in which .alpha. represents an inclination angle of the total fuel gas supply rate versus the intake air pressure (PM) characteristic curve, and .beta. represents an inclination angle of the subsidiary fuel gas supply rate through said subsidiary supply means versus the duty ratio characteristic curve, and
- said control amount setting means is constructed to calculate and set the control amount (D) in accordance with the equation D.rarw.DB+DF, based on the basic amount (DB) set by said basic amount setting means and the correction amount (DF) set by said correction amount setting means.
- 6. A method for controlling an air-fuel ratio in a gas engine, comprising the steps of:
- mixing an intake air and a fuel gas at a mixing area to form an air/fuel mixture at said mixing area for supply to a gas engine;
- supplying, to said air/fuel mixture, at least one of the intake air and the fuel gas, said supplying being through a subsidiary supply which is downstream of said mixing area and which bypasses said mixing area;
- detecting a concentration of oxygen in an exhaust gas exhausted from said gas engine;
- detecting operating conditions of said gas engine;
- setting a basic amount of gas supplied through said subsidiary supply in accordance with the operating conditions of said gas engine;
- setting a correction amount of gas proportional to a total fuel gas supply rate including an amount of fuel gas supplied directly to said mixing area in said mixing step and an amount of fuel gas supplied through said subsidiary supply in said supply step, in accordance with the operating conditions of said engine and oxygen concentrations in said exhaust gas; and
- setting a control amount of gas supplied through said subsidiary supply means by adding the correction amount of gas to the basic amount of gas.
Priority Claims (1)
Number |
Date |
Country |
Kind |
2-110873 |
Apr 1990 |
JPX |
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Parent Case Info
This application is a division of application Ser. No. 690,825, filed Apr. 26, 1991, now U.S. Pat. No. 5,154,053.
US Referenced Citations (6)
Foreign Referenced Citations (3)
Number |
Date |
Country |
58-72647 |
Apr 1983 |
JPX |
60-92742 |
Jun 1985 |
JPX |
61-138840 |
Jun 1986 |
JPX |
Divisions (1)
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Number |
Date |
Country |
Parent |
690825 |
Apr 1991 |
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