Patent ID: 6099270
Filing Date: 2000-08-08
Classification: F04B

Abstract:
A piston for use in a metering device having a chamber, the piston comprising:a first grooved end section having a head, an angled channel circumferentially disposed about the piston, and means for providing a fluid flowing connection from the angled channel and out the head; the angled channel having a first side, a second side, and a base portion therebetween, the channel base portion oriented at an angle from the first side to the second side, with the channel having a depth that is greater adjacent the first side; and the angled channel sized to receive a movable sealing member therein;a stem section having a first end, a second end, an exterior surface, and a diameter effective to provide a space along the exterior surface of the stem section when the piston is disposed within a chamber of the metering device; anda second end section;wherein when the sealing member is seated in and adjacent to the first side of the angled channel, there is fluid communication between the space along the exterior surface of the stem section, the angled channel, and the fluid flowing connection means in the grooved end section of the piston, and when the sealing member is adjacent to the second side of the angled channel, the space along the exterior surface of the stem section is blocked by the sealing member to prevent fluid communication between the space along the exterior surface of the piston and the angled channel.