Patent ID: 7275477
Filing Date: 2007-10-02
Classification: F04B

Abstract:
1. A piston assembly for an air pump, comprising a plate having a first indentation on a bottom surface of said plate, a through first exhaust hole being provided perpendicular to said plate within said first indentation; a ring where said plate is laterally embedded, said ring having a central opening; a connecting rod whose one end is connected to the crankshaft of said air pump and the other end is molded into a supporting seat, said plate and said ring being bolted to said supporting seat by a plurality of fastening elements, said supporting seat having a second indentation on a top surface of said supporting seat corresponding to said first indentation, a through second exhaust hole being provided perpendicular to said supporting seat within said second indentation substantially aligned with said first exhaust hole, said central opening of said ring allowing said first and second indentations jointed with each other, and at least a flexible exhaust valve piece whose portion is pressed between said plate and said supporting seat while the other portion is housed inside said space formed by said first and second indentations, said first and second indentations being configured such that said space allows said exhaust valve piece to flip inside said space; wherein, when said piston assembly moves backward away from the cylinder of said air pump, said exhaust valve piece flips forward to cover said first exhaust hole; when said piston assembly moves forward into the cylinder of said air pump, said exhaust valve piece flips backward to cover said second exhaust hole; and, when said piston assembly is not moving, said exhaust valve piece returns to its un-bended state by its own flexibility, allowing air to flow through said first and second exhaust holes.