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Automatic door closer constructed for releasably holding a door in a predetermined partly open position

  • US 4,234,996 A
  • Filed: 10/25/1978
  • Issued: 11/25/1980
  • Est. Priority Date: 03/30/1978
  • Status: Expired due to Term
First Claim
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1. In an automatic door closer, a combination comprising, an elongated housing provided with an axial cylindrical bore closed at opposite ends;

  • a closer shaft adapted to be connected to a door and mounted in said housing intermediate the ends of the latter turnable about an axis extending transverse to the axis of said bore;

    piston means guided in said bore and dividing the bore into two compartments for a damping fluid, said piston means being operatively connected to said closer shaft and reciprocatable in said bore between a first end position in which a door connected to the closer shaft is fully closed, a predetermined intermediate position in which the door is partly opened, and a second end position in which the door is fully opened;

    biasing means cooperating with the piston means for urging the same to said first end position, said biasing means comprising a coil compression spring in one of said compartments abutting with opposite ends against said piston means and one of said closed ends of said housing;

    a first and a second passage extending through said piston means;

    a one-way valve in said first passage biased to permit flow of fluid in one direction from said one compartment into the other of said compartments during movement of said piston means from said first towards said second end position and concomitant reduction of the volume of said one compartment while preventing flow of fluid in the opposite direction; and

    means for closing said second passage when said piston means reaches said predetermined intermediate position to thereby hold said piston means against the force of said biasing means in said intermediate position, said means for closing said second passage comprising a valve member and a compression spring abutting with opposite ends respectively against said valve member and said one closed end of said housing and normally holding said valve member in closed position, the force of said compression spring may be overcome by applying an outer force to the door connected to said closer shaft to turn the latter in a direction to move said piston means from said predetermined intermediate position to said first end position, said means for closing said second passage including said valve member being located within said coil compression spring.

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