Patent ID: 6257849
Filing Date: 2001-07-10
Classification: F04B

Abstract:
A manual air pump comprising:an outer cylinder (80) comprising a chamber (83) therein and including a first end and a second end,a head (82) provided to the second end of the outer cylinder, the head including an outlet passage (91) communicated with the chamber (83) for supplying air to an object to be inflated,an inner cylinder (50) reciprocatingly mounted in the outer cylinder and including a longitudinal hole (55), the inner cylinder including a first end distal to the head and a second end adjacent to the head, an outer piston (60) being attached to the second end of the inner cylinder (50) to move therewith, the outer piston including a passage (63) that is intercommunicated between the longitudinal hole (55) of the inner cylinder (50) and the outlet passage (91) of the head (82),a piston rod (10) reciprocatingly mounted in longitudinal hole (55) of the inner cylinder (50) and having a first end and a second end, an inner piston (40) being attached to the second end of the piston rod to move therewith,a handle (11) secured to the first end of the piston rod (10) to move therewith, anda switch member (30) rotatably mounted to the first end of the outer cylinder (80) and around the first end of the inner cylinder (50), the switch member being rotatable between a first position for securing the piston rod (10) to the inner cylinder (50) to allow joint sliding movement of the piston rod and the inner cylinder such that reciprocating movement of the handle (11) causes high volume/low pressure inflation and a second position for securing the inner cylinder (50) to the outer cylinder (80) and for disengaging the piston rod (10) from the inner cylinder (50) such that reciprocating movement of the handle (11) causes low volume/high pressure inflation.