Pumps – Expansible chamber type – Moving cylinder
Reexamination Certificate
2000-04-12
2001-07-10
Thorpe, Timothy S. (Department: 3746)
Pumps
Expansible chamber type
Moving cylinder
C417S487000, C417S562000, C417S569000, C417S468000, C417S238000
Reexamination Certificate
active
06257849
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a manual air pump for inflating, e.g., bicycle tires, and more particularly to dual-mode manual air pump 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 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. U.S. Pat. No. 5,443,370 issued to Wang on Aug. 22, 1995 proposes a two-cylinder manual air 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, manufacture, assembly, and use of such manual air pump are complicated and troublesome. The structure in the cylinders for air passage is too complicated. In addition, the thinner piston rod might be broken during the output stroke, as the travel for the thinner piston rod is relatively long and the piston on the thinner piston rod encounters much higher pressure when the piston approaches the inner end of the outer cylinder. Namely, the thinner piston rod tends to be broken and requires a larger force to push it. Further, the manual air pump is too long when in a fully extended status. Further, the manual air pump generates noise during inflation.
SUMMARY OF THE INVENTION
A manual air pump in accordance with the present invention comprises:
an outer cylinder comprising a chamber therein and including a first end and a second end,
a head provided to the second end of the outer cylinder, the head including an outlet passage communicated with the chamber for supplying air to an object to be inflated,
an inner cylinder reciprocatingly mounted in the outer cylinder and including a longitudinal hole, the inner cylinder including a first end distal to the head and a second end adjacent to the head, an outer piston being attached to the second end of the inner cylinder to move therewith, the outer piston including a passage that is intercommunicated between the longitudinal hole of the inner cylinder and the outlet passage of the head,
a piston rod reciprocatingly mounted in longitudinal hole of the inner cylinder and having a first end and a second end, an inner piston being attached to the second end of the piston rod to move therewith,
a handle secured to the first end of the piston rod to move therewith, and
a switch member rotatably mounted to the first end of the outer cylinder and around the first end of the inner cylinder, the switch member being rotatable between a first position for securing the piston rod to the inner cylinder to allow joint sliding movement of the piston rod and the inner cylinder such that reciprocating movement of the handle causes high volume/low pressure inflation and a second position for securing the inner cylinder to the outer cylinder and for disengaging the piston rod from the inner cylinder such that reciprocating movement of the handle causes low volume/high pressure inflation.
The second end of the inner cylinder includes an inner threaded section and wherein the outer piston includes a stud for engaging with the inner threaded section of the inner cylinder.
The second end of the piston rod includes a screw hole and wherein the inner piston includes a stud for engaging with the screw hole of the piston rod.
An inner periphery defining the longitudinal hole of the inner cylinder includes a longitudinal guide strip, and the piston rod includes a longitudinal groove defined in an outer periphery thereof for receiving the longitudinal guide strip, thereby preventing relative rotational movement between the inner cylinder and the piston rod.
A cap is securely mounted to the fist end of the outer cylinder. The cap includes a longitudinal hole through which the inner cylinder extends. The cap further includes a first stop. The switch member includes a second stop and a skirt. A disc is formed between the first end of the piston rod and the handle and includes a third stop. When the switch member is in the first position, the second stop of the switch member is in overlapped relationship with the third stop of the disc, thereby allowing joint sliding movement of the piston rod and the inner cylinder, and the skirt is not in overlapped relationship with the first stop of the cap, thereby allowing joint longitudinal movement of the inner cylinder and the piston rod relative to the outer cylinder. When the switch member is in the second position, the second stop of the switch member is not in overlapped relationship with the third stop of the disc, thereby allowing longitudinal sliding movement of the piston rod relative to the inner cylinder, and the skirt is in overlapped relationship with the first stop of the cap, thereby preventing longitudinal movement of the inner cylinder relative to the outer cylinder.
An inner periphery defining the longitudinal hole of the cap includes a longitudinal groove, and the inner cylinder includes a longitudinal guide strip formed on an outer periphery thereof and guided in the longitudinal groove, thereby preventing relative rotational movement between the inner cylinder and the cap.
The switch member is manually movable to a third position in which the second stop of the switch member is in overlapped relationship with the third stop of the disc and the skirt is in overlapped relationship with the first stop of the cap, thereby preventing longitudinal movement of the inner cylinder and the piston rod relative to the outer cylinder.
An engaging disc is securely mounted around the first end of the inner cylinder and received in the switch member. The engaging disc includes a recessed portion defined in a side thereof. A peripheral wall defining the recessed portion includes an inner threading for engaging with an outer threading on the first end of the inner cylinder.
In a modified embodiment of the invention, the switch member includes a groove and a second stop partially received in the groove. An elastic element is being mounted in the groove for biasing the second stop radially outward. The second stop includes an inclined surface in an underside thereof.
In another modified embodiment of the invention, the switch member includes a slot to thereby define a second stop in an end edge thereof, and the second stop includes an inclined surface in an underside thereof.
Other objects, advantages, and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.
REFERENCES:
patent: 624917 (1899-03-01), Feeny
patent: 799786 (1905-09-01), Freel
patent: 1522370 (1925-01-01), Jenney
patent: 2450295 (1948-09-01), Parker et al.
patent: 4508490 (1985-04-01), Ramirez et al.
patent: 5443370 (1995-08-01), Wang
patent: 5655890 (1997-08-01), Liao
patent: 5779457 (1998-07-01), Chuang et al.
patent: 5873705 (1999-02-01), Chen
Kamrath Alan
Rider Bennett Egan & Arundel LLP
Solak Timothy P.
Thorpe Timothy S.
LandOfFree
Manual air pump having selectable high pressure and high... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Manual air pump having selectable high pressure and high..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Manual air pump having selectable high pressure and high... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2485089