| 摘要 |
PURPOSE:To enable an engine, when it is placed in an idle condition, to hold a stable idle speed, by improving the flow characteristic of an air flow control valve provided in a bypass passage. CONSTITUTION:In the case of a power steering device being actuated when an engine is placed in an idle condition, an amount of air, passing through a passage 5, is changed as shown in the drawing by controlling an air flow control valve 10, provided in the second bypass passage 5, to be opened and closed. That is, the amount of air continues increasing before it reaches a predetermined amount A after a control pressure of oil exceeds the preset pressure P1. And if the amount of air reaches the predetermined amount A, no change is generated in the amount of air before the control pressure of oil exceeds the preset value of pressure P3. Consequently, air-fuel ratio in the initial time of power steering operation obtains a lean state due to an injection delay of fuel, but the air-fuel ratio comes to be lean to a small extent because the control pressure of oil generates no change between the pressures from P2 to P3. While a flow of air in the bypass passage 5 increases if the control pressure of oil exceeds the value P3, but the air-fuel ratio comes to be lean to a small degree with the amount of air smaller than the conventional amount of increase (dotted line), and the possibility of an engine stop small decreases. |
