Linear suction control system

摘要

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 17. The resulting vacuum is proportional to the flow rate through the valve 11 and thus to the current through the solenoid 30. A transducer 16 samples the vacuum output and produces a signal fed to a differential amplifier 17. The signal is compared in negative feedback fashion with a variable input voltage set by a potentiometer 18 or other variable voltage source, so that the transducer signal tracks the voltage source signal. The voltage source can comprise a potentiometer 18 actuated by a foot switch 19 or the like, so that angular position of the foot switch 19 relates directly and predictably to the vacuum output of the converter 13. The linear solenoid valve 11 includes an electromagnetic coil 30 arranged to translate a valve member 36, with an elastic member 35 biasing the valve member closed with a generally linear restoring force.