| 摘要 |
<p>A valve comprises an inlet chamber (a), a fluid outlet chamber (c) and a bellows chamber (b) defined by a bellows (22) communicating with the inlet chamber (a) via a bleed hole (54). One or both of a restrictor (32) and an end portion (24) of the bellows (22) are flexible and they can abut one another or can come into or out of abutment by relative flexure. The restrictor (32) is disposed between the inlet and outlet chambers (a and c) and has apertures (34, 36) that are closed or opened depending upon whether the seat (32) and bellows end portion (24) are or are not in abutment. When the valve is to be opened, an armature (18) of a solenoid (20) communicates the bellows and outlet chambers (b and c) via a hole (52), the resultant pressure drop in the bellows chamber (b) causing the movable seat (32) and bellows end chamber (24) to come out of abutment to communicate the inlet and outlet chambers (a and c) via the apertures (34, 36). When the valve is to be closed, the armature (18) closes the hole (52) whereby the pressure in the bellows chamber (b) increases by virtue of the bleed hole (54) and the restrictor (32) and bellows end portion (24) come into abutment to close the valve. The restrictor (32) may comprise a movable seat movable away from a fixed seat (30) after the restrictor and bellows end portion (24) have flexed apart so as to increase the extent of communication between the inlet and outlet chambers (a and c). </p> |
