Sliding door operator

An automatic door operator used in opening and closing a door which is mounted upon a door frame for sliding movement in a vertical plane between open and closed positions in response to movement of traffic adjacent the door, said door operator comprising:

• a drive cylinder for mounting relative to said door frame having first and second fluid ports;
• a piston slideably movable within said drive cylinder through door opening and door closing strokes between said first and second fluid ports;
• a drive means for connecting said piston to a door to drive the door through the door opening and door closing strokes;
• means for supplying pressurized fluid from a suitable source thereof connected to said first fluid port and operable to supply pressurized fluid thereto;
• control means coupled to said supplying means connecting said source to said first fluid port and connecting said second fluid inlet to exhaust continuously throughout an opening stroke of the door;
• said control means including means for reducing the pressure of fluid supplied through said first port on an opening stroke after a portion of said stroke has been completed;
• and
• exhaust metering means metering the exhaust flow of fluid at least as the door approaches the end of its stroke.

An automatic door operator used in opening and closing a door which is mounted upon a door frame for sliding movement in a vertical plane between open and closed positions in response to movement of traffic adjacent the door, said door operator comprising:

• a drive cylinder for mounting relative to said door frame having first and second fluid inlets;
• a piston slideably movable within said drive cylinder through door opening and door closing strokes between said first and second fluid inlets;
• a drive means for connecting said piston to a door movable through door opening and door closing strokes;
• means for supplying pressurized fluid from a suitable source thereof for moving said piston in said cylinder;
• first and second pneumatic switches;
• cam means carried on said door adapted to shift said switches in response to the position of the door relative to said frame;
• a directional control valve means for alternating connecting said first and second fluid inlets selectively to said means supplying pressurized fluid and to exhaust respectively;
• a speed control valve connected between said directional control valve and exhaust for metering the exhaust flow at different rates;
• a shuttle valve controlling the mode of operation of said speed control valve between said different rates;
• a secondary speed control valve connected between said directional control valve means and said first fluid inlet selectively metering the inlet flow from said supply means;
• a solenoid valve;
• a transfer valve connected to said solenoid valve and said means supplying pressurized fluid and further connected to said pneumatic switches;
• and
• conduit means interconnecting said pneumatic switch with said shuttle valve, and secondary speed control valve.