| 摘要 |
<p>A two stage exhaust gas recirculation (EGR) valve (10) delivers a wide range of EGR flow while operating with a valve actuator such as a solenoid (12) with smaller sized coil (14) and armature (16). An attached valve body (34) mounts concentric dual pintle valves including a larger first valve (56), which engages a valve seat (42) in the valve body (34) to control exhaust gas flow between inlet (52) and outlet (54) openings and a smaller second valve (58) positioned inside the first valve and engaging a second valve seat (70) in the head (60) of the first valve (56). The second valve (58) controls a low flow passage (72) inside the first valve. The solenoid armature (16) engages only the smaller second valve (58) during a first stage of its stroke so that the smaller valve is opened first and flow control is maintained in a low flow range. Exhaust and intake differential pressures acting on the second valve (58) are overcome by a smaller armature force because of the smaller area of the second valve. In a second stage of its stroke, the armature (16) also engages the first valve, forcing it off its seat (42) and providing a greater amount of exhaust flow. Opening of the larger first valve (56) requires less force than a single pintle valve.</p> |
