| 摘要 |
A negative pressure control apparatus for controlling an exhaust gas recirculation control valve for a diesel engine. The apparatus has a negative pressure chamber and an atmospheric pressure chamber with a diaphragm therebetween. The negative pressure chamber has an inlet port which is connected to a vacuum, and an outlet port which provides the controlled negative pressure. The atmospheric pressure chamber contains an electromagnet whose force is varied according to the load of the diesel engine. The diaphragm is fixed to a magnetic material and has a communication channel between the negative and atmospheric pressure chambers. A movable tubular body is inserted in the communication channel to provide communication between the negative pressure chamber and the inlet port. A valve plug is also inserted into the communication channel to provide communication between the negative and the atmospheric pressure chambers. The diaphragm deforms in accordance with the pressure differential in the two chambers and the magnetic attraction between the magnetic material fixed to the diaphragm and the electromagnet in the atmospheric pressure chamber. As the diaphragm deforms, the movable tubular body and the valve plug operate to provide alternate venting between the negative pressure chamber and the inlet port, and the negative and atmospheric pressure chambers. Thus, controlled negative pressure corresponding to the load on the diesel engine, is supplied at the outlet port. For controlling the output, an adjustment member is provided which allows external adjustment of the gap between the electromagnet and the diaphragm. |
