Automatic door operator for swing doors

An automatic door operator for a swing door supported by a door supporting frame to swing about a vertical axis, comprising:

• (a) opening and closing means attached to the swing door, for opening and closing the swing door;
• (b) a support plate;
• (c) an electric motor supported on one side of the support plate and having a rotation shaft;
• (d) speed reducing means comprising a gear train disposed on the other side of the support plate and connected to the rotation shaft, the speed reducing means having a last gear member disposed remotely from the rotation shaft;
• (e) a door closer supported on the one side of the support plate, including:
• a hollow cylinder having closed opposite ends and containing an oil therein;
• a piston member slidably and sealingly fitted into the cylinder and axially spring-biased to close the door, the piston member having a first passage and a second passage formed therethrough, each of said passages communicating one side of the cylinder to the other side, the second passage having a check valve incorporated therein so that the check valve is closed when the piston member is moved in a direction to close the door;
• and
• a rack member attached to the piston member to extend in the axial direction of the cylinder;
• a drive shaft perpendicularly passing through and rotatably supported by the support plate so as to be connected to the opening and closing means for driving the opening and closing means, the drive shaft passing through the wall of the cylinder and having a pinion mounted on one end portion thereof to engage with the rack member of the piston member, and the drive shaft further having the last gear of the speed reducing means mounted on the other end portion thereof;
• (g) control means for electrically controlling the motor to swing the door;
• (h) sensing means for sensing a body accessing the door to thereby provide an electric signal to the control means to energize the motor to open the swing door;
• and
• (i) detecting means for detecting an open angle degree of the swing door, the detecting means including:
• a program cam operatively connected to the drive shaft for being rotated;
• and
• a photo detector for detecting the shape of the program cam to thereby provide an open angle degree signal to the control means for controlling the rotation of the motor.