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Pneumatic door closer

  • US 10,352,079 B2
  • Filed: 09/12/2017
  • Issued: 07/16/2019
  • Est. Priority Date: 02/25/2016
  • Status: Active Grant
First Claim
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1. A pneumatic door closer of a door pivotally mounted in a door frame, comprising:

  • a guide track on the door frame;

    first and second piston assemblies on the door;

    a rod having a first end slidably mounted in the guide track and a second end attached to the first piston assembly;

    the first piston assembly having a first piston;

    the second piston assembly having a second piston with first and second gas chambers on opposite sides of the second piston;

    the first and second pistons moving in unison when the door opens and closes;

    a first passage between the first and second gas chambers to allow gas flow from the second chamber to the first chamber when the door is opening; and

    a second passage between the first and second gas chambers to allow gas flow from the first chamber to the second chamber, the second passage comprising an axial inlet, an axial outlet, a throttle passage, and a radial vent hole, wherein the throttle passage extends along a labyrinthine path on a radial surface of the second piston to connect the axial outlet and the radial vent hole;

    wherein when the door is closing, the first passage is sealed forcing the gas to flow from the first chamber through the axial inlet, the axial outlet, the throttle passage, and the radial vent hole, in turn, and into the second chamber, so as to dampen door closing.

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