US 4,467,602 AGranted

Split engine control system

AssigneeNissan Motor Co., Ltd.

InventorsHaruhiko Iizuka, Fukashi Sugasawa

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Abstract

A split engine control system operates a multiple cylinder internal combustion engine by using only some of the plurality of cylinders under light load conditions. The total number of cylinders are split into a first cylinder group which is always activated during engine operation and a second cylinder group which is deactivated under light load conditions. The engine is provided with an exhaust passage which consists of first and second upstream exhaust passages connected to the first and second cylinder group, respectively, and a common downstream exhaust passage. An exhaust gas sensor and a first catalytic converter are disposed in the first upstream exhaust passage, and a second catalytic converter is disposed in the common downstream exhaust passage. A temperature sensor is provided in the second catalytic converter. When the temperature of the second catalytic converter is above a certain level during the partial cylinder mode, the engine is feedback controlled by a signal from the exhaust gas sensor and the exhaust gases are purified by the first catalytic converter. When the temperature is below the level during the partial cylinder mode, the air-fuel mixture is enriched with respect to the stoichiometric point so as to promote reduction of the NOx component of the exhaust gases in the first catalytic converter and oxidation of the remaining HC and CO components in the second catalytic converter.

Claims6

Dependent claims

A split engine control system, comprising:

(a) a plurality of cylinders separated into first and second cylinder groups;
(b) a split engine control means for operating said engine under light load conditions in a partial cylinder mode in which only said first cylinder group is activated and said second cylinder group is deactivated and allowed to pump air therethrough, and for operating said engine under relatively heavy load conditions in a full cylinder mode in which said first and second groups are activated;
(c) first and second upstream exhaust passages for passing gases exhausted from said first and second cylinder groups, respectively, to a common junction;
(d) a common downstream exhaust passage connected to said common junction for passing said gases therethrough to the atmosphere;
(e) a first exhaust gas sensor and a first catalytic converter disposed in said first upstream exhaust passage;
(f) a second catalytic converter disposed in said common downstream exhaust passage;
(g) a temperature sensor for detecting the temperature of said second catalytic converter;
(h) a feedback control means responsive to a signal from said first exhaust gas sensor for maintaining the ratio of the air-fuel mixture supplied to said first cylinder group at the stoichiometric point;
and
(i) a first means responsive to a signal from said temperature sensor for disabling said feedback control means and controlling the ratio of the air-fuel mixture supplied to said first cylinder group at a point which lies to the rich side of the stoichiometric point when the temperature of said second catalytic converter is below a predetermined level during the partial cylinder mode.

7 more elements

Dependencies are inferred from the claim text.