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Dispenser having an improved metering chamber

  • US 4,972,978 A
  • Filed: 12/13/1988
  • Issued: 11/27/1990
  • Est. Priority Date: 12/13/1988
  • Status: Expired due to Fees
First Claim
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1. An apparatus for dispensing liquids, pastes, creams or pellets comprising:

  • a cylinder including an interior surface defining a circumference of the cylinder and having an opening at one end of the cylinder and at least one port on the interior surface of the cylinder;

    at least one biasing member, disposed within the cylinder, including;

    a first end in a substantially fixed position relative to the cylinder; and

    an opposite second end being closer to the cylinder opening than the biasing member first end is to the cylinder opening;

    a piston assembly, disposed for being partially received in the cylinder through the cylinder opening, including;

    a rod extending through the biasing member and having a first end which is further from the cylinder opening than the biasing member first end and having a second end disposed exteriorly of the cylinder;

    a flange extending from the rod and having a surface facing the second end of the biasing member;

    means, mounted on the piston rod near the second end of the rod, for receiving an actuating force to move the piston assembly flange surface in a direction towards the fixed position first end of the biasing member;

    at least one hinging member, mounted on the first end of the piston assembly rod, including first and second opposing surfaces;

    means, disposed within the cylinder in a substantially fixed position relative to the cylinder, for pushing the hinging member second surface in a direction approximately towards the port when the hinging member is moved with the piston assembly rod so that the hinging member first surface can be forced against the cylinder interior surface to substantially close the port;

    means for stopping movement of the piston assembly when the piston assembly actuating force receiving means moves a predetermined distance away from the cylinder opening; and

    a seal, disposed within the cylinder, on the piston assembly rod and between the piston assembly flange surface and the biasing member second end, which continuously engages a circumferential segment of the cylinder interior surface when the piston assembly is prevented from movement by the stopping means, the biasing member second end is exerting a force on the seal and the stopped piston assembly flange surface is exerting an opposing force on the seal, and which continuously engages a circumferential segment of the cylinder interior surface when the piston assembly rod is moved in response to an actuating force which is sufficient to overcome an opposing biasing member force, the moved piston assembly flange surface is exerting a force on the seal and the biasing member second end is exerting an opposing force on the seal.

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