| 摘要 |
PURPOSE:To enhance the reliability of a venturi pump used as a vacuum source of a vacuum cup type transfer device, by utilizing a pneumatic type computer to control the change-over among supply sources for compressed air fed to the venturi pump without using electrical contacts. CONSTITUTION:Vacuum pressure obtained from a venturi 20 which is connected to a compressed air supply source 21 through a three-position four-way solenoid selector valve 22, is acted upon a vacuum cup 24 through the selector valve 22. The vacuum pressure in the vacuum cup 24 is used as an input signal Pv fed to a pneumatic type computer 25 whose outlet signal Po is fed as a pilot pressure for the selector valve 22 which is therefore controlled by the computer 25, thereby the vacuum pressure of the vacuum cup 24 is regulated. As a result the consumption rate of compressed air may be reduced. The transfer device is actuated by delivering turn-on and -off signals to the selector valve 22. |
