Patent ID: 6848667

Claim:
A valve for controlling fluid flow comprising: (1) a chamber of non magnetisable material having an inlet opening and at least one outlet opening, (2) a magnetisable armature comprising a valve closure member, (3) an electromagnetic drive for moving the closure member from one end to the other of a path defined by the chamber, (4) first passage means communicating with at least the inlet opening for supplying fluid under positive pressure to the chamber and second passage means communicating with the at least one outlet opening, (5) a seating at each end of the path within the chamber, each seating being complementary to the external surface of the closure member, so that the closure member is a snug fit in each seating, said at least one outlet opening being located in or adjacent one of the seatings, so that positioning the closure member in that seating closes off the outlet and prevents fluid from leaving the chamber via the second passage means, (6) permanent magnet means and pole pieces for creating two opposite, spaced apart powerful magnetic fields in each of which the flux extends across the chamber perpendicular to the direction of movement of the closure member, (7) solenoid means surrounding the chamber which when energised creates a second magnetic field, in which the flux is parallel to that of the permanent fields, and (8) circuit means adapted to cause current to flow in one direction or the other in the solenoid, whereby the second field will reinforce the flux in one of the permanent fields and reduce it in the other, thereby to cause the armature to move from the weaker field to the stronger and thereby move from one seating to the other so as to change the state of the valve.