High speed driving method and apparatus of pressure cylinder

A high speed driving apparatus of a pressure cylinder, comprising:

• a pressure cylinder comprising a piston configured to be driven by an air pressure, a piston rod connected to the piston, and a head-side pressure chamber and a rod-side pressure chamber formed on opposite sides of the piston;
• a servo valve connecting both the pressure chambers to an air pressure source;
• a control section configured to control the servo valve;
• and
• a position detector configured to detect an operation position of the piston rod to feed back a detected position signal to the control section;
• wherein
• the high speed driving apparatus further comprises a control apparatus configured to function such that the control section compares the detected position signal fed back from the position detector and a set position signal to stop the piston rod as previously set, and to control the servo valve such that a deviation between both the signals becomes zero, to thereby stop the piston rod at a set position, and to maintain a state in which substantially same pressures are supplied to the pressure chambers formed on opposite sides of the piston, wherein
• the pressure cylinder comprises a cushioning mechanism configured to reduce a speed of the piston rod in the vicinity of an end of a forward stroke of the piston by limiting a flow rate of an exhaust gas from the rod-side pressure chamber, and
• a quick exhaust valve is connected to the pressure cylinder and is configured, if an internal pressure in the rod-side pressure chamber at the time of the cushioning effect function becomes less than an internal pressure in the head-side pressure chamber, to act as a trigger to actuate the quick exhaust valve to directly open the rod-side pressure chamber into atmosphere.