Air-fuel ratio control system for multi-cylinder engine
AssigneeDenso Corporation
InventorJiro Kondo
Life of this patent
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Abstract
An engine control system has a controller and intake control devices for controlling air amount introduced into each of the cylinders. The controller has a lean burn control block and a warm up control block. Both blocks operate two cylinders under a lean air-fuel ratio, and operate remaining two cylinders under a rich air-fuel ratio. Both blocks control at least the intake control devices to adjust air-fuel ratio.
Claims30
An air-fuel ratio control system for multi-cylinder engine having a first cylinder, a second cylinder, and an exhaust passage in which exhaust gas from both the first and second cylinders flows, the system comprising:
- a first intake control device for controlling an amount of intake air introduced into the first cylinder;
- a second intake control device for controlling an amount of intake air introduced into the second cylinder;
- and
- a controller which controls the first and second intake control devices to operate the first cylinder under a fuel lean air-fuel ratio and to simultaneously operate the second cylinder under a fuel rich air-fuel ratio, when the engine is operated under a predetermined condition;
- each of the first intake control device and the second intake control device having an intake valve and an actuator driving the intake valve in a partially opened position when the actuator is not excited.
A method of controlling an air-fuel ratio in a multi-cylinder engine having a first cylinder, a second cylinder, and an exhaust passage in which exhaust gas from both the first and second cylinders flows, the method comprising:
- controlling an amount of intake air introduced into the first cylinder via a first intake control device having an intake valve and an actuator;
- controlling an amount of intake air introduced into the second cylinder via a second intake control device having an intake valve and an actuator;
- and
- controlling the first and second intake control devices to operate the first cylinder under a fuel lean air-fuel ratio and to simultaneously operate the second cylinder under a fuel rich air-fuel ratio, when the engine is operated under a predetermined condition;
- and
- controlling the first and second intake control devices so that the intake valve of the first intake control device is in a partially opened position when the actuator of the first intake control device is not excited and the intake valve of the second intake control device is in a partially opened position when the actuator of the second intake control device is not excited.
Dependencies are inferred from the claim text.