Patent ID: 8051534
Filing Date: 2011-11-08
Classification: E05F,E05Y,Y10T

Abstract:
1. A pneumatic door closer comprising: an elongated cylinder having opposed end walls, one of said end walls having a rod opening therein, a piston reciprocally disposed within said cylinder to define a spring side vacuum chamber appropriately sealed and capable of selectively maintaining a pressure substantially lower than normal atmospheric pressure substantially indefinitely on said rod opening side of said piston and a pressure chamber on the other side of said piston within said cylinder, said piston including a unidirectional valving means for controlling unidirectional passage of air between said spring side vacuum chamber and said pressure chamber, a piston rod connected to said piston, said piston rod having a free end extending through said rod opening, a controlled vent place on the other one of the opposed end walls adjacent said pressure chamber, whereby pressure may be controllably released from said pressure chamber as said piston moves towards said controlled vent, a seal placed in the rod opening around said piston rod at said one of said end walls, wherein said seal is capable of maintaining a pressure substantially lower than normal atmospheric pressure substantially indefinitely in the spring side vacuum chamber, spring means disposed within said cylinder and said spring side vacuum chamber for imparting a spring bias on said piston to normally urge said piston toward the other end wall of said opposed end walls, and a breather means disposed intermediate the opposed end walls of said elongated cylinder and selectively in communication with said spring side vacuum chamber for controlled introduction of air into said spring side vacuum chamber for decreasing the level of vacuum created in said spring side vacuum chamber and selectively in communication with said pressure chamber for allowing additional air from the pressure chamber to escape during the closing stroke of the piston, wherein when said piston rod is fully extended and said piston is between said seal and said breather means and said piston advances towards the other one of the opposed end walls a vacuum begins to be created in said spring side vacuum chamber and air in said pressure chamber is vented to atmosphere through said controlled vent and said breather means whereby a vacuum is formed in the spring side vacuum chamber providing a substantial resistance force acting against said spring means slowing a closing speed of a door until said piston passes said breather means preventing additional air escaping from said pressure chamber and permitting atmospheric air to leak into said spring side vacuum chamber through said breather means gradually diminishing the vacuum in said spring side vacuum chamber resulting in a substantially uniform closing speed until said piston is adjacent the other one of the opposed end wall.