A linear suction control system 10 includes a linear solenoid valve 11 which exhibits a flow through rate having a known proportional relationship with the current through the solenoid 30. Regulated fluid pressure 12 is fed through the linear solenoid valve 11 to a venturi-type pressure vacuum converter...http://www.google.es/patents/US4838281?utm_source=gb-gplus-sharePatente US4838281 - Linear suction control system
