Spiral valve actuator for air compressor

Abstract

A worm drive actuator for a spiral valve that opens and closes bypass ports on a rotary screw air compressor is provided.

What is claimed is: 
     
         1 . An air compressor comprising:
 a compression chamber having an inlet and an outlet, the compression chamber defined by two radially intersecting axial bores, wherein each said bore contains an air compression screw;   at least one bypass port in said compression chamber, wherein said at least one bypass port when open is in fluid communication with a spiral valve chamber that contains a spiral valve, wherein rotation of the spiral valve opens or closes the at least one bypass port; and   a worm drive that actuates the spiral valve, the worm drive comprising:
 a worm gear coupled to the spiral valve, and 
 a worm driven by an electric motor. 
   
     
     
         2 . The air compressor of  claim 1  comprising an effective compression volume of the compression chamber produced when at least one bypass port is open which is smaller than a closed compression volume produced when at least one bypass port is closed. 
     
     
         3 . The air compressor of  claim 1  wherein the at least one bypass port comprises multiple bypass ports, with a first port located closer to the compression chamber outlet than a second port.