Honda Giken Kogyo Kabushiki Kaisha

Junichi Suzuki

Yosuke Tachibana

Shun Masuda

Tomoya Furukawa

Masayuki Ueno

Masayuki Wakui

Osamu Kitamura

The invention provides an electronic control unit for controlling an air/fuel ratio of an engine having a lean NOx catalyst in its exhaust system in order to prevent the decrease of the fuel efficiency without deterioration of the drivability due to a rich operation for reducing the NOx catalyst. The electronic control unit includes: an air/fuel ratio control system for changing the air/fuel ratio to a rich side when the amount of NOx occluded by the lean NOx catalyst exceeds a predetermined value and changing said air/fuel ratio back to a lean side when a first predetermined period has elapsed; a lagging system for lagging ignition timing in synchronization with the air/fuel ratio changing to the rich side by said air/fuel ratio control system; and decrementing system for decreasing the amount of the ignition timing lagged by the lagging system by a predetermined amount when a second predetermined period shorter than said first predetermined period has elapsed after the air/fuel ratio changing to the rich side. According to the invention, it is possible to prevent the decrease of the fuel efficiency without the deterioration of the drivability due to the rich operation to reduce the NOx catalyst because the ignition timing is lagged in synchronization with the air/fuel ratio changing to the rich side and the lagged amount is decremented after a predetermined period has elapsed. In one embodiment, the decrementing system gradually decrements said lagging amount up to a hold value.

Electronic control unit for controlling ignition timing during reduction of NOx occluded by lean NOx catalyst

There is provided a valve timing control system for an internal combustion engine, which is capable of enhancing the accuracy of valve timing control. The valve timing control system for the internal combustion engine changes the cam phase of an intake cam a relative to a crankshaft to thereby control the valve timing of an intake valve The valve timing control system fixes a desired cam phase CAINCMD at a value CAINCMDFC during an fuel cut-off, and controls a cam phase change mechanism such that from a time t during the fuel cut-off, the cam phase is held at a value assumed at the time t Further, the valve timing control system calculates a learned value DCALEARN of the amount of deviation of an actual cam phase CAIN based on a plurality of values of the actual cam phase CAIN detected at and after the time t and the constant value CAINCMDFC of the desired cam phase CAINCMD (step S ).

Valve timing control system for internal combustion engine

There is provided a valve timing control system for an internal combustion engine, which is capable of properly setting the reference position of the cam phase by learning, and at the same time promptly establishing a learned value of the reference position when the learned value is lost, thereby accurately changing the cam phase for proper control of the valve timing of the engine. A cam phase change mechanism changes the cam phase. A reference value indicative of a reference position of the cam phase is learned at a predetermined learning speed based on the cam phase detected when the cam phase change mechanism is in a predetermined operative state, and the learned reference value (learned value) is stored in a RAM. When the loss of the learned value from the RAM is detected, a learning speed at the reference value is learned is corrected such that the learning speed is increased from the predetermined learning speed for a predetermined time period.

Growing community of inventors

Wako, Japan

Junichi Suzuki