Oil-less air compressor

Abstract

An oil-less air compressor mainly includes a motor, a crankcase, and a piston rod moving in the crankcase in rotary motion for external air to enter the crankcase via an air inlet thereof and be discharged from an air cylinder via an air outlet thereof into an external air tank. The air inlet of the crankcase is provided with a plurality of connecting bars to connect to a column centered in the air inlet, an annular filter element is mounted on the central column, and an end cap having a central hole is fitted in the center of the air inlet, so that external air could smoothly pass through the air inlet via through holes formed between the connecting bars.

1 . An oil-less air compressor, comprising a motor, a crankcase, and a piston rod moving in said crankcase in rotary motion for external air to enter said crankcase via an air inlet thereof and be discharged from an air cylinder via an air outlet thereof into an externally connected air tank for storage; said oil-less air compressor being characterized in that said air inlet of said crankcase is provided with a cover defining a centered round opening, in which a plurality of connecting bars are provided to connect at an end to an inner edge of said round opening, and at an opposite end to a column located at a center of said round opening, such that a plurality of through holes are formed in said air inlet by said connecting bars between said round opening and said central column; that an annular filter element is mounted at a central hole on said central column; and that an end cap having a central hole is fitted in said round opening of said cover by engaging a plurality of retaining studs spaced on an inner side of said end cap with the inner edge of said round opening.  
   
   
       2 . The oil-less air compressor as claimed in  claim 1 , wherein said piston rod has a piston head, on which a centered fixing hole and a plurality of through holes spaced around said fixing hole are provided; and wherein a check valve in the form of a round disc having a centered through hole is loosely screwed to said fixing hole on said piston head to keep said piston head in a completely plane surface; whereby when said piston head is in an upward compress stroke with said check valve tightly bearing against said piston head, no residual air pressure would form in said air cylinder at said piston head, allowing air to move into and discharge from said air cylinder more smoothly.