Patent ID: 6120265
Filing Date: 2000-09-19
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 first passage,an inner tube securely mounted in the main body and having an interior communicated with the main passage of the head, the inner tube including a first end secured in the first end of the main body 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 adjacent to the head and a second chamber distal to the head, the first chamber being communicated with atmosphere via the first passage of the head, the hollow piston 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 the 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 and slidable along the longitudinal direction of the hollow piston, a second O-ring being mounted in the second annular groove and slidable along the longitudinal direction of the hollow piston, 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 first transverse hole defined therein to communicate an interior of the second section with a first 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 first 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 a compartment therein for partially receiving the inner tube,a plug mounted in the piston rod and secured to the second end of the inner tube, the plug separating the compartment in the piston rod into a third chamber that is adjacent to the piston and a fourth chamber that is distal to the piston, the second end of the piston rod including a second passage that communicates with the fourth chamber with atmosphere, the plug including a third annular groove defined in an outer periphery thereof and adjacent to the piston and a fourth annular groove defined in the outer periphery thereof and distal to the piston, the third annular groove including a third notch extended along a longitudinal direction of the inner tube and distal to the piston, the fourth annular groove including a fourth notch extended along a longitudinal direction of the inner tube and adjacent to the inner tube, a third O-ring being mounted in the third annular groove and slidable along the longitudinal direction of the inner tube, a fourth O-ring being mounted in the fourth annular groove and slidable along the longitudinal direction of the inner tube, the plug further including a second transverse hole extended between the third annular groove and the fourth annular groove along a radial direction to communicate an interior of the inner tube with a second space between the third annular groove, the fourth annular groove, and an inner periphery of the piston rod,an end cap mounted to seal the second end of the main body and including a third passage that communicates the second chamber of the main body with atmosphere,a second valve means mounted in second end of the piston rod such that air is only flowable from atmosphere to the fourth chamber of the piston rod via the second passage of the piston rod,a third valve means mounted 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 third 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 first space and the second chamber while the first O-ring prevents communication between the first chamber and the first space, the third O-ring is moved to abut an end edge of the third notch to allow communication between the third chamber and the second space while the fourth O-ring prevents communication between the fourth chamber and the second space, such that air in the second chamber is outputted to the main passage via the first space, the first transverse hole, the third chamber, the second space, the second transverse hole, and the inner tube, while ambient air enters the first chamber via the first passage of the head and enters the fourth chamber via the second passage in the second end of the piston rod, 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 first space and the first chamber while the second O-ring prevents communication between the second chamber and the first space, the fourth O-ring is moved to abut an end edge of the fourth notch to allow communication between the second space and the fourth chamber while the third O-ring prevents communication between the third chamber and the second space, such that air in the fourth chamber is outputted to the main passage via the second space, the second transverse hole, and the inner tube, while air in the first chamber enters the third chamber via the first space and the first transverse hole.