Patent ID: 8793837
Filing Date: 2014-08-05
Classification: E05F,E05Y,Y10T

Abstract:
1. A pneumatic door closer for controllably closing a door comprising: an elongated cylinder having opposing front and rear end walls; a piston reciprocally disposed within said elongated cylinder separating said elongated cylinder into a vacuum side having an initial volume and a pressure side; a piston rod attached to said piston and extending out of the front end wall of said elongated cylinder; a piston seal between said piston and an internal surface of said elongated cylinder, said piston seal preventing airflow in the pressure side upon retraction of said piston rod within said elongated cylinder, whereby a vacuum is formed between said piston and the front end wall; a vacuum seal formed in the front end wall and placed around said piston rod, said vacuum seal maintaining a vacuum within the vacuum side of said elongated cylinder as said piston rod is retracted within said elongated cylinder; said piston further having a volume displacer extending from one side thereof towards the front end wall, said volume displacer occupying substantially all of the initial volume of the vacuum side when the door is fully open wherein said volume displacer reduces the initial volume of the vacuum side and wherein the initial volume at the start of a closing stroke and upon release of the door results in a stronger resistance force being imparted on said piston, so as to slow the rate of closing during an initial closing phase of the door, and a compression spring placed around said volume displacer and positioned between said piston and the front end wall, said compression spring being compressed when the door is fully open, whereby resulting resistance forces acting on said piston are enhanced and a uniform door closing is obtained.