Hydraulically controlled pneumatic swinging door operator

#While hydraulic swinging door operators have been highly developed, plants, stores, and other buildings with already established pneumatic systems frequently prefer that their door operators likewise be powered in this fashion. Among other things, there is some feeling that a pneumatic system is more trouble free than a hydraulic system.

#The present invention includes a continuous loop entrained over two spaced sprockets, one of which is adapted for connection to a door to drive or be driven by the door in opening and closing. One side of the loop between the sprockets incorporates a pneumatic piston enclosed within a pneumatic cylinder. Springs on each side of the piston within the cylinder maintain the piston normally in a central, door-closed position. Depending on the desired direction of movement of the door, either end of the pneumatic cylinder is connected to a source of air under pressure through mat-switch or similarly controlled valving means. The other side of the loop has a hydraulic piston therein contained within a hydraulic cylinder. Passageways provide for the controlled flow of hydraulic fluid from one side of the piston to the other. The hydraulic system is purely passive, simply following the movement of the pneumatic piston, and serves only to control and restrain the movement of the door.

#The advantages of this structure are many. The same unit can be employed for left or right hand doors opening either inward or outward. Pneumatic pressure in itself, without restraint, is an unsatisfactory power source for door operators because of its elasticity. The hydraulic controller in the present invention imposes a non-elastic response to the pneumatic pressure and has the capability of adjustably controlling the rate of movement of the door differently at different points in the arc of its swing.

#FIG. 1 is a top plan view of a device embodying the invention as applied to a double door, shown with cover removed;

#FIG. 2 is a section taken along the line 2--2 of FIG. 1 looking in the direction of the arrows with certain parts omitted showing the relationship of the hydraulic controller and the pneumatic system of the door operator;

#FIG. 3 is a section taken substantially along the line 3--3 of FIG. 1 looking in the direction of the arrows;

#The preferred embodiment will be first described in general terms and the structural details described later. It includes a box 10 adapted to the mounted to the lintel of a doorway overlying the axis of hinging of a single door or, in the case of double doors, extending to overlie the axis of hinging of both doors. Within the box is mounted the pneumatic operator unit 12 and a slave assembly 14 in the event the invention is to be applied to the double door situation. The slave assembly will be omitted in a single door application. The pneumatic operator unit 12 includes a drive sprocket 16 keyed as at 18 to a vertical drive spindle 20 which extends through the bottom of the box 10 and is formed to a square section 22 at its lower end for a driving or a driven connection to the top edge of a swinging door at its axis of hinging.

#A horizontal continuous loop 24 including a drive sprocket length of roller chain 26, a take up sprocket length of roller chain 28, a hydraulic rod 30, and a pneumatic piston 32 is entrained over the drive sprocket 16 and a horizontally displaced take-up sprocket 34 to effect driving or driven engagement with the sprocket 16.

#The piston 32 is contained in a sleeve 36 or pneumatic cylinder which is closed at the drive sprocket end by a drive sprocket housing 38 and at the other end by a take up sprocket housing 40. The two housings also support their respective sprockets 16 and 34 for rotation. Inlets 42 for air under pressure are provided in each housing. One or the other of these inlets will be used, depending on the desired opening movement of the door, but generally not both unless it is desired that the door open in upon ingress and out upon egress. The inlet ports 42 will be connected through a two way valve 44 to a source of air under pressure 46. The valve 44 is solenoid 48 energized through a normally open mat switch 50 and a normally closed cam operated switch 51 to deliver air into the cylinder when the mat switch is closed and to permit exhaust from the cylinder when the solenoid is de-energized. Safety switches and time delays are involved in the de-energization of the solenoid, but as these are old and well known, they have not been shown.