Vacuum generating device

Claim 1

A vacuum control device comprising a body having an inlet port adapted for connection to a source of air under pressure and an outlet port for connection to a suction pad, a bore formed in said body receiving air from said inlet port, a piston located in said bore and having a central through passage for said air, said piston and said bore defining an expansion chamber at the rear end and an expansion chamber at the front end of said bore, an air jet ejector axially aligned with the front end of said bore comprising a nozzle and an aspirator chamber surrounding said nozzle, and duct means for communication of said aspirator chamber with said outlet port, said piston having a seal at its forward tip and being movable between a first position wherein said tip is spaced from said nozzle permitting said air under pressure to flow into said nozzle to create a vacuum in said aspirator chamber, and a second position wherein said seal seats against the rear end and of said nozzle to block the flow of air under pressure to said nozzle, and means for selectively feeding air under pressure to the front and rear chambers to move said piston into one or the other of said first and second positions.