Patent ID: 7464437

Claim:
A door closer which is fabricated in a hydraulic or air cylinder shape in its body and being installed to a door ( 10 ) or a doorframe ( 11 ), wherein a subsidiary plate ( 9 a ) with a subsidiary pin ( 9 b ) is assembled to a door mounting device ( 9 ) installed at the door ( 10 ), and a rotatable force adjustment nut ( 7 ) is assembled to the subsidiary plate ( 9 a ) so that it can change the position of a piston rod ( 3 ) to the door ( 10 ) or to the doorframe ( 11 ); wherein a cylinder ( 1 ) is assembled to a doorframe mounting device ( 8 ) installed at the doorframe ( 11 ), a surface of the cylinder ( 1 ) being hemi-cylindrical, in which an oil-hole is formed and a speed adjustment bolt is assembled at end thereof, extending linearly in the longitudinal direction along a piston ( 2 ), and a spring ( 5 ) is mounted in the cylinder ( 1 ) and hydraulic oil containing a little amounts of air is filled in the cylinder ( 1 ), the piston rod ( 3 ) is extending from an inner side to an outer side of the cylinder ( 1 ), one end of the piston rod ( 3 ) being provided with the piston ( 2 ) and the other end thereof being provided with male screw ( 3 a ) in which minor diameter of an external thread is greater than a diameter of the piston rod ( 3 ); and wherein the door mounting device ( 9 ) including the force adjustment nut ( 7 ), subsidiary plate ( 9 a ) and subsidiary pin ( 9 b ), and the doorframe mounting device ( 8 ) including the cylinder ( 1 ), the piston rod ( 3 ) and the male screw ( 3 a ), can be assembled and separated from each other by the force adjustment nut ( 7 ) provided at the door mounting device ( 9 ), and the male screw ( 3 a ) provided at the one end of the piston rod ( 3 ).