Apparatus for opening and closing a door

A door-opening apparatus comprising:

• a housing;
• a reversible motor in said housing having a motor output;
• a wormgear journaled in said housing;
• first transmission means for linking said motor output to said wormgear for joint rotation, said first transmission means including an input drive wheel connected to said motor output and continuously jointly rotatable therewith;
• a rotatable output member connectable to a door and rotatable in one sense to open said door and in the other sense to close said door;
• second transmission means for linking said wormgear to said output member for joint rotation;
• clutch means in said second transmission means for decoupling said wormgear from said output member when rotation of said output member is resisted with a torque exceeding a given limit torque;
• a control disk in said housing;
• third transmission means for rotating said control disk jointly with but at a much slower angular speed than said output member;
• an opening stop and a closing stop mounted at angularly offset locations on said control disk
• respective opening and closing switches engageable with said opening and closing stops in open and closed positions of said door;
• electrical control means connected to said switches and to said motor for allowing operation of said motor only in a sense to open said door when said closing stop engages said closing switch and for allowing operation of said motor only in a sense to close said door when said opening stop engages said opening switch;
• said electrical control means including:
• an outer tubular shaft member carrying said wormgear,
• an inner shaft member axially and angularly displaceable in said outer shaft member, one of said members being formed with an axially V-shaped cutout,
• a pin on the other of said members engaging radially in said pin;
• spring means for urging said pin axially into said cut-out whereby relative rotation of said shaft members will axially displace said inner shaft member in said outer shaft member into an outer position, and
• switch means engageable with said inner shaft member only in said outer position thereof for reversing said motor;
• and
• safety means for reversing the operation of said motor when said stops are out of engagement with said switches and when displacement of said door is resisted with a force exceeding a given limit force.