Pumps – Expansible chamber type – Plural pumping chambers
Reexamination Certificate
1999-06-16
2001-02-20
Walberg, Teresa (Department: 3742)
Pumps
Expansible chamber type
Plural pumping chambers
C417S259000
Reexamination Certificate
active
06190142
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to manual air pumps for inflating, e.g., bicycle tires, and more particularly to dual-mode manual air pumps that may in one mode provide a very high volume of air per stroke and in another mode provide less volume of air at high pressure.
2. Description of the Related Art
Bicycle pumps, as mentioned in U.S. Pat. No. 5,676,529 to Hermansen et al. issued on Oct. 14, 1997, include two typical types: 1) big bore for high volume per stroke and low pressure for rapid inflation, yet high pressure operation is difficult to achieve; and 2) small bore for low volume per stroke and high pressure for inflating bicycle tires to high pressure. Hermansen et al. proposes a compact manual pump having selectable high volume and high pressure modes, wherein the pump in one mode provides a very high volume of air per pump stroke and in another mode provides less volume per stroke but enables the user to inflate to higher pressures. Nevertheless, in the output stroke shown in
FIG. 4
of U.S. Pat. No. 5,676,529, air from the rear chamber defined between the outer tube
12
and the inner tube
24
must pass through the interior of the inner tube
24
before it enters a front chamber defined in the middle cylindrical tube
14
. It is found that high pressure inflation is not reliable and unsatisfactory.
The present invention is intended to provide manual air pumps that mitigate and/or obviate the above problem.
SUMMARY OF THE INVENTION
A manual air pump in accordance with the present invention comprises:
an outer tube including a first end and a second end,
an inner tube coaxially mounted in the outer tube and including a first end and a second end, an inner chamber being defined in the inner tube, an outer chamber being defined between the outer tube and the inner tube,
a head coupled to the first end of the outer tube and the first end of the inner tube, the head including a main passage communicated with the inner chamber and the outer chamber for supplying air to an object to be inflated,
a piston assembly including:
an inner piston rod having a first end with an inner piston slidably received in the inner chamber and a second end, the inner piston separating the inner chamber into a first chamber section adjacent to the head and a second chamber section distal to the head,
an outer piston rod having a first end with an outer piston slidably received in the outer chamber and a second end, the outer piston separating the outer chamber into a third chamber section adjacent to the head and a fourth chamber section distal to the head, and
a handle secured to the second end of the inner piston rod and the second end of the outer piston rod to move therewith,
means for supplying ambient air into the second chamber section and the fourth chamber section during an outward stroke of the handle away from the head,
a release passage for communicating one of the first chamber section and the third chamber section with environment, and
switchable valve means mounted in the release passage, wherein the release passage is blocked when the switchable valve means is in a first status, and wherein the release passage is opened when the switchable valve means is in a second status such that air is only flowable from said one of the first chamber section and the third chamber section to environment.
The head includes a passage through which air is flowable from the first chamber section to the main passage, and a one-way valve is mounted in the passage such that air is only flowable from the first chamber section to the main passage.
The head may further includes a passage through which air is flowable from the third chamber section to the main passage, and a one-way valve is mounted in the passage such that air is only flowable from the third chamber section to the main passage.
The inner piston includes an annular groove defined in an outer periphery thereof and including a first end edge and a second end edge. An O-ring is mounted in the annular groove and so arranged that an air path is defined to allow air to flow from the second chamber section to the first chamber section when the O-ring abuts against the first end edge of the annular groove as a result of the outward stroke of the handle away from the head and that the air path is blocked when the O-ring abuts against the second edge of the annular groove as a result of an inward stroke of the handle toward the head.
The outer piston includes an annular groove defined in an outer periphery thereof and having a first end edge and a second end edge. An O-ring is mounted in the annular groove and so arranged that an air path is defined to allow air to flow from the fourth chamber section to the second chamber section when the O-ring abuts against the first end edge of the annular groove as a result of the outward stroke of the handle away from the head and that the air path is blocked when the O-ring abuts against the second end edge of the annular groove as a result of an inward stroke of the handle toward the head.
The air supplying means includes a first passage defined between the second end of the outer tube and the outer piston rod, a second passage defined between the second end of the inner tube and the inner tube, and an opening defined in the second end of the outer piston rod.
In a first embodiment of the invention, the release passage is defined in the head and communicates the first chamber section with environment. The switchable valve means includes a one-way valve and an elastic member mounted in the release passage and a manually operable switch key for switching the switchable valve means between the first status and the second status.
In a second embodiment of the invention, the outer tube includes an extension tube extended from an outer periphery thereof, the release passage is defined in the extension tube that communicates the third chamber section with environment. The switchable valve means includes a one-way valve and a first elastic member mounted in the extension tube, a sleeve mounted around the extension tube and enclosing a distal end of the extension tube, and a valve stem slidably received in the extension tube and having an end extended beyond the sleeve for manual operation between the first status and the second status. The sleeve further includes a notch. The valve stem includes a block. The notch of the sleeve is blocked by the block of the valve stem when the switchable valve means is in the first status such that air in the fourth chamber section is not flowable to environment. The notch is not blocked by the block of the valve stem when the switchable valve means is in the second status such that air in the fourth chamber section is flowable to environment during an inward stroke of the handle.
In a third embodiment of the invention, the inner piston rod includes a hollow interior communicated with environment, and the release passage is defined in the inner piston and communicates the first chamber section with the hollow interior of the inner piston rod. The switchable valve means includes a one-way valve mounted in the release passage and an operative rod having a first end operably connected to the one-way valve and a second end extended beyond the handle for manual operation. The one-way valve is closed when the operative rod is in a first position. The one-way valve is opened when the operative rod is in a second position such that the hollow interior of the inner piston rod communicates with environment and that air is only flowable from the first chamber section to the hollow interior of the inner piston rod.
In a fourth embodiment of the invention, a mediate chamber is defined between the outer piston rod and the inner tube, the mediate chamber being communicated with environment via a chamber defined between the outer piston rod and the inner piston rod. The release passage is defined in the outer piston and communicates the third chamber section with the mediate chamber. The switchable valve means includes a one-way valve mou
Robinson Daniel
Rosenberg , Klein & Lee
Walberg Teresa
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