Apparatus and method for internal-combustion engine control
First Claim
1. A control apparatus for an internal combustion engine having an exhaust purifying catalytic device disposed in an exhaust passage for reducing emission of nitrogen oxide to atmosphere, the exhaust purifying catalytic device being operable to adsorb nitrogen oxide contained in exhaust gases discharged from the internal combustion engine when the engine is in a lean-combustion mode where an air-fuel ratio of an air-fuel mixture supplied to the engine is leaner than a theoretical air-fuel ratio, and to deoxidize adsorbed nitrogen oxide when the internal combustion engine is in a rich-combustion mode where the air-fuel ratio is equal to or richer than the theoretical air-fuel ratio, comprising:
- adsorption state estimating means including first nitrogen oxide discharge amount estimating means for estimating a discharge amount of nitrogen oxide from the exhaust purifying catalytic device, and said adsorption state estimating means estimating an adsorption state of nitrogen oxide adsorbed by the exhaust purifying catalytic device based on said estimated discharge amount of nitrogen oxide from the exhaust purifying catalytic device; and
combustion-state deteriorating means for deteriorating a combustion state of the internal combustion engine according to the adsorption state of nitrogen oxide estimated by said adsorption state estimating means when the engine is in the lean-combustion mode.
3 Assignments
0 Petitions
Accused Products
Abstract
In a control apparatus and control method for an internal combustion engine having an exhaust purifying catalytic device for adsorbing nitrogen oxide contained in exhaust gases from the engine, the adsorption state of nitrogen oxide adsorbed by the catalytic device is estimated by an electronic control unit during the lean-combustion driving of the engine. If the catalytic device is saturated with nitrogen oxide, the ignition timing is delayed and the exhaust gas is recirculated to the intake side of the engine with the lean air-fuel ratio kept unchanged. This starts the nitrogen oxide reduced driving mode for deteriorating the combustion state in the engine. At this time, the engine output will not change by a great amount. Further, a reducing atmosphere is created around the catalytic device by unburnt gases, generated due to the deterioration of the combustion state, to deoxidize the adsorbed nitrogen oxide. As a result, the purifying ability of the catalytic device can be recovered to suppress the discharge amount of nitrogen oxide without deteriorating the smoothness of engine driving and fuel economy.
156 Citations
80 Claims
-
1. A control apparatus for an internal combustion engine having an exhaust purifying catalytic device disposed in an exhaust passage for reducing emission of nitrogen oxide to atmosphere, the exhaust purifying catalytic device being operable to adsorb nitrogen oxide contained in exhaust gases discharged from the internal combustion engine when the engine is in a lean-combustion mode where an air-fuel ratio of an air-fuel mixture supplied to the engine is leaner than a theoretical air-fuel ratio, and to deoxidize adsorbed nitrogen oxide when the internal combustion engine is in a rich-combustion mode where the air-fuel ratio is equal to or richer than the theoretical air-fuel ratio, comprising:
-
adsorption state estimating means including first nitrogen oxide discharge amount estimating means for estimating a discharge amount of nitrogen oxide from the exhaust purifying catalytic device, and said adsorption state estimating means estimating an adsorption state of nitrogen oxide adsorbed by the exhaust purifying catalytic device based on said estimated discharge amount of nitrogen oxide from the exhaust purifying catalytic device; and combustion-state deteriorating means for deteriorating a combustion state of the internal combustion engine according to the adsorption state of nitrogen oxide estimated by said adsorption state estimating means when the engine is in the lean-combustion mode. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32)
-
-
33. A control apparatus for an internal combustion engine having an exhaust purifying catalytic device disposed in an exhaust passage for reducing emission of nitrogen oxide discharged to atmosphere, the exhaust purifying catalytic device being operable to adsorb nitrogen oxide, contained in exhaust gases discharged from the internal combustion engine when the internal combustion engine is in a lean-combustion mode where an air-fuel ratio of an air-fuel mixture supplied to the engine is leaner than a theoretical air-fuel ratio, and to deoxidize adsorbed nitrogen oxide when the engine is in a rich-combustion mode where the air-fuel ratio is equal to or richer than the theoretical air-fuel ratio, comprising:
-
nitrogen oxide discharge amount estimating means for estimating a discharge amount of nitrogen oxide from the exhaust purifying catalytic device; adsorption saturation determining means for determining whether the discharge amount of nitrogen oxide estimated by said nitrogen oxide discharge amount estimating means exceeds a predetermined amount; and combustion state changing means for changing the air-fuel ratio of the air-fuel mixture to change from the lean-combustion mode to the rich-combustion mode when said adsorption saturation determining means determines that the discharge amount of nitrogen oxide exceeds the predetermined amount in the lean-combustion mode. - View Dependent Claims (34, 35, 36, 37, 38, 39, 40)
-
-
41. An internal combustion engine control method for reducing emission of nitrogen oxide to atmosphere, by causing nitrogen oxide, contained in exhaust gases discharged from an internal combustion engine, to be absorbed by an exhaust purifying catalytic device, disposed in an exhaust passage of the internal combustion engine, when the engine is in a lean-combustion mode where an air-fuel ratio of an air-fuel mixture supplied to the engine is leaner than a theoretical air-fuel ratio, and by deoxidizing adsorbed nitrogen oxide by means of the exhaust purifying catalytic device when the internal combustion engine is in a rich-combustion mode where the air-fuel ratio is equal to or richer than the theoretical air-fuel ratio, comprising:
-
a) estimating an adsorption state of nitrogen oxide adsorbed by the exhaust purifying catalytic device, said step a) including a step a0) of estimating a discharge amount of nitrogen oxide from the exhaust purifying catalytic device, and estimating said adsorption state of nitrogen oxide adsorbed by the exhaust purifying catalytic device based on said estimated discharge amount of nitrogen oxide from the exhaust purifying catalytic device; and deteriorating a combustion state of the internal combustion engine according to the adsorption state of nitrogen oxide estimated in said step a) when the engine is in the lean-combustion mode. - View Dependent Claims (42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72)
-
-
73. An internal combustion engine control method for reducing emission of nitrogen oxide to atmosphere, by causing nitrogen oxide, contained in exhaust gases discharged from the internal combustion engine, to be absorbed by an exhaust purifying catalytic device disposed in an exhaust passage of the internal combustion engine when the engine is in a lean-combustion mode where an air-fuel ratio of an air-fuel mixture supplied to the internal combustion engine is leaner than a theoretical air-fuel ratio, and by deoxidizing adsorbed nitrogen oxide by means of the exhaust purifying catalytic device when the engine is in a rich-combustion mode where the air-fuel ratio is equal to or richer than the theoretical air-fuel ratio, comprising:
-
a) estimating a discharge amount of nitrogen oxide from the exhaust purifying catalytic device; b) determining whether the discharge amount of nitrogen oxide estimated in said step a) exceeds a predetermined amount; and c) changing the air-fuel ratio of the air-fuel mixture to change from the lean-combustion mode to the rich-combustion mode when it is determined in said step b) that the discharge amount of nitrogen oxide exceeds the predetermined amount in the lean-combustion mode. - View Dependent Claims (74, 75, 76, 77, 78, 79, 80)
-
Specification