Air-fuel ratio controlling method for internal-combustion engine

Abstract

Abstract PURPOSE:To compensate unevenness of the properties of a sensor, by controlling delay time in a compensation process of supplied fuel quantity following a reversion of the output of a first air-fuel ratio sensor in the upstream of a catalytic converter in relation to the output of a second air-fuel ratio sensor in the downstream. CONSTITUTION:When a mixture ratio is in rarefaction, both first and second air- fuel ratio sensors (unillustrated herein) generate low-level voltage but when it is overthick, they generate high-level voltage (A1 and A4), turning to wave-forms A2 and A5 after being rectified as compared with the assigned reference value. Next, at the time when the rectified wave-form A5 is reversed from 1 to 0, an integral wave-form A6 decreases by the assigned quantity (c), and at a period during which the A5 is kept at 0, it decreases by (d) at every interval but when the A5 is reversed from 0 to 1, the A6 increases each in the reverse way. The integral wave-form A6 determines delay time in the skip time of an integral wave-form A7 and during a period when it stays above a reference line A6v, that is, a period of being overthick, the delay time in a rising skip time increases but that in a falling time decreases so that a period when decreases a supply of fuel decreases is extended. On the contrary, while it is lower than the reference line A6v, the case goes in the reverse way.

Inventors

• 👤 Yoshiki Nakajo
• 👤 中條　芳樹
• 👤 Shigeru Uenishi
• 👤 上西　茂
• 👤 Keiji Aoki
• 👤 啓二 青木

Bibliographic Details