Mehrschritt-Ventilöffnungssteuervorrichtung

摘要

A multiple step valve opening control system, particularly for an EGR control valve unit, having a plurality of valve lifts. The system comprises a valve member (16) for opening a fluid passage (14) in multiple steps, a first piston (26) slidably housed in a housing (12), a second cylinder (28) substantially coaxial with the first piston (26), a second piston (30) fitted in the second cylinder (26) and coupled to the valve member (16), and a first piston stroke regulating member (46) which is moved selectively to a first position for regulating an allowable displacement of the first piston (26) to a first predetermined extent (l1) or to a second position for regulating the allowable displacement of the first piston (26) to the first predetermined first extent (l1) plus a third predetermined extent (l3). By changing the position of the first piston displacement regulating member (46), the valve member (16) is opened by various valve lifts.