| 摘要 |
<p>PURPOSE:To easily make a judgement on the failures or deterioration of an electric-driven air pump by providing a failure diagnostic passage to communicate the downstream of an air-flow meter to the electric--driven air pump in diagnosing the failures of the electric-driven air pump. CONSTITUTION:An air-flow meter 2 is used not only for measurement of the air flow rate as the parameter of the engine control, but also for diagnosis of the failures or the deterioration of an electric-driven air pump 3 from the changes in the air flow rate before and after the operation of the electric-driven air pump 3 for supplying the secondary air. Air flows in a failure diagnostic passage 4 when the failure diagnosis is made for the electric-driven pump 3. A normal traveling passage 5 is used to supply the air to an electric-driven air pump in the normal traveling. A switching valve 6 switches the failure diagnostic passage 4 from/to the normal traveling passage 5. Thus, the failures of the electric-driven air pump can be made in an extremely simple manner. A judgement can be made on the deterioration of the electric-driven air pump, leading to the failure diagnosis in an early stage.</p> |
