| 摘要 |
In the electrically heated catalytic converter system according to the present invention, the catalytic converter is provided with an electric heater. The electric heater is turned on by a switching device for a predetermined time period after the engine starts in order to heat the catalytic converter. When the switching device fails in such a manner that the switching device cannot turn off the electric heater even after the predetermined time period lapsed, the catalytic converter is heated by the electric heater even after the catalyst reaches the activating temperature. This may cause an excessive temperature rise and damage to the catalytic converter. The electronic control unit of the engine monitors the electric current supplied to the electric heater, and if the electric current is supplied to the electric heater continuously after the predetermined time period lapsed, the electronic control unit lowers the setting of the maximum limit of the speed of the engine to a value determined by the degree of opening of the throttle valve. Therefore, the engine is operated at a relatively low speed when the switching device has failed and the amount of the exhaust gas flowing through the catalytic converter is reduced. Thus the amount of the heat transferred from the exhaust gas to the catalytic converter is reduced, and an excessive temperature rise of the catalytic converter is suppressed. |
