A solenoid valve for fluid flow control, in which the solenoid has an armature movable within a core in response to current in a field coil. The armature is shaped as a cone with a hemispherical end so as to give a power output that is a substantially linear function of said current. Valve control means...http://www.google.fr/patents/US4132384?utm_source=gb-gplus-shareBrevet US4132384 - Auxiliary power system and apparatus
