| 摘要 |
PURPOSE:To prevent the deterioration of an oxygen sensor by stopping the electric current feed to a chemical pump-type mixture fed to an internal-combustion engine is thicker than the theorectical air-fuel ratio when controlling the air-fuel ratio of a car internal-combustion engine. CONSTITUTION:A chemical pump-type oxygen sensor 10 generating an eletric output corresponding to the oxygen density in the exhaust gas is provided on the exhaust pipe 9 of an internal-combustion engine 1, and an oxygen sensor control unit 18 feeds the electric current to the oxygen sensor 10 and also detects an electric output corresponding to the oxygen density in the exhaust gas. In addition, individual output signals from an excess flow meter 4, an intake air temperature detector 8, a rotation number detector 11, and the control unit 18 are fed to an electronic control unit 19, which instructs the driving frequency and driving time of a fuel injection valve 5 to an injection valve driving unit 20. During a predetermined time when the internal-combustion engine 1 is being warmed up after its start, it is operated at an air-fuel ratio thicker than the theoretical one, the operation of the oxygen sensor 10 is stopped, thus the deterioration of the oxygen sensor 10 due to the electric current feed is prevented. |
