Split engine control system

• US 4,467,602 A
• Filed: 10/25/1982
• Issued: 08/28/1984
• Est. Priority Date: 10/28/1981
• Status: Expired due to Fees

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Iizuka, Haruhiko, Sugasawa, Fukashi
• Primary Examiner(s): Hart, Douglas
• Application Number:
  US06/436,517
• Time in Patent Office: 673 Days
• Field of Search: 60/276, 60/278, 60/285, 60/301, 123/198 F
• US Class Current: 60/276
• CPC Class Codes: B01D 53/9495 Controlling the catalytic process
• CPC Class Codes: F01N 13/009 having two or more separate purifying devices arranged in series
• CPC Class Codes: F01N 2430/02 by cutting out a part of engine cylinders
• CPC Class Codes: F01N 2430/06 by varying fuel-air ratio, e.g. by enriching fuel-air mixture
• CPC Class Codes: F01N 3/20 specially adapted for catalytic conversion F01N3/22 takes precedence; Methods of operation or control of catalytic converters
• CPC Class Codes: F01N 9/00 Electrical control of exhaust gas treating apparatus monitoring or diagnostic devices for exhaust-gas treatment apparatus F01N11/00; conjoint electrical control of two or more combustion engine functions F02D43/00
• CPC Class Codes: F02D 17/02 Cutting-out cutting-out engines in multiple engine arrangements F02D25/04
• CPC Class Codes: F02D 41/0087 Selective cylinder activation, i.e. partial cylinder operation deceleration cut-off F02D41/123
• CPC Class Codes: F02D 41/1443 with one sensor per cylinder or group of cylinders
• CPC Class Codes: Y02T 10/40 Engine management systems

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.

Claims

1. 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.

2. A split engine control system as recited in claim 1, wherein said feedback control means is also responsive to a signal from a second exhaust gas sensor disposed in said common downstream exhaust passage during the full cylinder mode of operation.

3. A split engine control system as recited in claim 1, further comprising;

an exhaust gas recirculation system which is activated during the full cylinder mode, and a second means for disabling said feedback control means during the full cylinder mode.

4. A split engine control system as recited in claim 1, further comprising;

an air intake passage provided therein with an airflow sensor and a throttle valve and divided downstream of said throttle valve into first and second branches, communicating with said first and second cylinder groups respectively, a first stop valve provided in said second branch for shutting off same during the partial cylinder mode, a bypass passage connecting said intake passage upstream of said air flow sensor and said throttle valve to said second branch downstream of said first stop valve, and a second stop valve disposed in said bypass passage for shutting off same during the full cylinder mode.

5. A split engine control system as recited in claim 2, further comprising;

an air intake passage provided therein with an airflow sensor and a throttle valve and divided downstream of said throttle valve into first and second branches, communicating with said first and second cylinder groups respectively, a first stop valve provided in said second branch for shutting off same during the partial cylinder mode, a bypass passage connecting said intake passage upstream of said air flow sensor and said throttle valve to said second branch downstream of said first stop valve, and a second stop valve disposed in said bypass passage for shutting off same during the full cylinder mode.

6. A split engine control system as recited in claim 3, further comprising;

an air intake passage provided therein with an airflow sensor and a throttle valve and divided downstream of said throttle valve into first and second branches, communicating with said first and second cylinder groups respectively, a first stop valve provided in said second branch for shutting off same during the partial cylinder mode, a bypass passage connecting said intake passage upstream of said air flow sensor and said throttle valve to said second branch downstream of said first stop valve, and a second stop valve disposed in said bypass passage for shutting off same during the full cylinder mode.