Patent ID: 8235677

Claim:
A compressing diaphragm pump having automatic air expelling feature for spray use comprises: a motor; an upper hood chassis disposed along the top of the output shaft of said motor, said upper hood chassis comprising plural screw bores formed on an outer rim; multiple wobble wheels are pivoted on said upper hood chassis to serve as the pumping action in manner from axial reciprocal wobbling movement being driven by the output shaft of said motor; a diaphragm covering said upper hood chassis; a piston valve inset in said diaphragm; an anti-backflow plastic gasket with three piston slices closely fixed on said piston valve respectively and an upper hood, wherein an air discharge assembly and a plunger body are disposed at the wall of the water exit port of the upper hood, wherein said air discharge assembly, which is a hollow tube, has a pair of first air discharge cylinder and second air discharge cylinder running freely through each other disposed on the upper section and lower section thereof respectively such that the diameter of the first air discharge cylinder being larger than that of the second air discharge cylinder, wherein an air passage is pierced at the wall between the first air discharge cylinder and the water exit port of the top upper hood as well as an air discharge orifice is pierced of the central top surface of the air discharge assembly facing towards the second air discharge cylinder, and said plunger body, which is a hollow tube with a top plunger opening and a bottom plunger baffle with outer diameter of the plunger opening is smaller than that of the plunger baffle, has a compressed spring disposed therein from the plunger opening facing inwards and a through pore pierced on the wall thereof near the plunger baffle as well as an O-ring gasket rimmed thereon the peripheral between the through pore and the plunger baffle, wherein, both of the plunger opening and the plunger baffle are inset in the second air discharge cylinder and first air discharge cylinder of the air discharge assembly respectively.