Patent ID: 6065947
Filing Date: 2000-05-23
Classification: F04B

Abstract:
A pump comprising:a main body defining a chamber therein and including a first end and a second end,a head mounted to the first end of the main body and including a main passage that is adapted to be communicated with a valve, the head further including a side passage,an inner tube securely mounted in the main body and including a first end communicated with the main passage of the head and a second end,a hollow piston slidably received in the main body, the hollow piston separating the chamber of the main body into a first chamber and a second chamber, the first chamber being communicated with atmosphere via the side passage of the head, the hollow piston head further including a first annular groove defined in an outer periphery thereof and adjacent to the first end of the main body, the hollow piston head further including a second annular groove defined in an outer periphery and adjacent to the second end of the main body, the first annular groove including a first notch extended along a longitudinal direction of the hollow piston, the second annular groove including a second notch extended along the longitudinal direction of the hollow piston, a first O-ring being mounted in the first annular groove, a second O-ring being mounted in the second annular groove, the hollow piston including an inner periphery, the inner periphery including a reduced first section in sliding and sealing contact with an outer periphery of the inner tube, the inner periphery further including a second section having an inner diameter greater than that of the reduced first section, the hollow piston further including a transverse hole defined therein to communicate an interior of the second section with a space between the first O-ring, the second O-ring, and an inner periphery of the main body,a first valve means mounted in first end of the main body such that air is only flowable from atmosphere to the first chamber of the main body via the side passage,a hollow piston rod having a first end attached to the piston and a second end extended outside the main body, the hollow piston rod including an interior for partially receiving the inner tube and communicated with the interior of the second section of the piston,an end cap mounted to seal the second end of the main body and including a passage that communicates the second chamber of the main body with atmosphere,a second valve means mounted to in second end of the main body such that air is only flowable from atmosphere to the second chamber of the main body via the passage of the end cap,a handle attached to the second end of the piston rod for operation,wherein when during an outward stroke of the piston in which the handle moves away from the main body, the second O-ring is moved to abut an end edge of the second notch to allow communication between the space and the second chamber while the first chamber is not communicated with the space, such that air in the second chamber is outputted to the main passage via the space, the interior of the hollow piston rod, and the inner tube, while ambient air enters the first chamber via the side passage of the head, andwherein when during an inward stroke of the piston in which the handle moves toward the main body, the first O-ring is moved to abut an end edge of the first notch to allow communication between the space and the first chamber while the second chamber is not communicated with the space, such that air in the first chamber is outputted to the main passage via the space, the interior of the hollow piston rod, and the inner tube, while ambient air enters the second chamber via the passage of the end cap.