Electromagnetic fluid flow control valve

A fluid flow valve comprising:

• 1) a housing having a wall which defines a chamber,
• 2) an opening in the housing wall,
• 3) a magnetisable stator,
• 4) an armature adapted to move in a see-saw manner relative to the stator within the chamber,
• 5) the stator having four magnetic poles which define two bistable home positions of the armature, such that in one home position the armature makes contact with two of the poles, and in the other home position the armature makes contact with the other two poles,
• 6) at least one permanent magnet,
• 7) a flux path between pairs of the poles which is completed when the armature is in either of its two home positions, magnetic flux originating from the permanent magnet linking the armature and the two poles with which the armature is in contact and serving to hold the armature in contact therewith,
• 8) a curved surface in the middle of the armature,
• 9) a complementary curved surface between two of the poles within which the armature curved surfaced is received, the curved surface on the armature having a radius of curvature which is smaller than that of the complementary curved surface, so that the armature can roll within the latter as the armature moves between its two home positions,
• 10) at least one opening in the complementary curved surface which is covered by the curved surface on the armature when in the one home position and is uncovered when in the other home position, to control the flow of fluid therethrough, and
• 11) spring means which acts on the armature and creates a force urging the curved surfaces into contact.