Oil-less compressor with seal-dust protection

Abstract

An oil-less compressor, having polymeric seals and a crank mechanism which is vulnerable to dust arising from such seals, is provided with a dust-exclusion barrier that protects the crank mechanism from being exposed to such dust. The first stage of the compressor preferably draws its intake from the crankcase, providing a pressure differential and gas flow that sweeps seal dust away from the crank mechanism.

1 . A gas compressor assembly comprising:
 a) a gas compressor having at least a first stage with at least one cylinder with a piston having dry seals;   b) a piston rod connected to said piston and extending into a crank case cavity;   c) a crank mechanism located in the crank case cavity to operate said piston rod;   d) a low pressure gas supply inlet for connection to a source of gas and delivery of gas to said first stage; and   e) a high-pressure gas discharge outlet on said gas compressor for delivery of compressed gas to an external reservoir;   
     said compressor assembly further comprising a dust control enclosure within the crank case cavity having a sidewall through which the piston rod passes, said dust control enclosure forming a barrier between the dry seals and the crank mechanism that excludes dust from the dry seals from accessing the crank mechanism. 
   
   
       2 . A gas compressor assembly as a  claim 1  wherein the low pressure gas supply inlet delivers gas to the crank case cavity in the region of the crank mechanism on the crankshaft side of the dust enclosure and the first stage of the compressor takes its intake of gas to be compressed from the crank case cavity on the piston side of the dust control enclosure through a cylinder supply valve, there being a gas flow path extending from the region of the crank mechanism to the portion of the crankcase cavity on the piston side of the dust control enclosure whereby a pressure differential may be formed in operation across the barrier formed by the dust control enclosure. 
   
   
       3 . A gas compressor assembly as a any one of  claims 1  or  2  wherein the dust control enclosure is in the form of a sleeve or cap providing said sidewall, the sidewall having a penetration through the sidewall fitted with a dust-excluding dust seal through which the piston rod passes. 
   
   
       4 . A gas compressor assembly as a  claim 3  wherein said dust seal is in the form of washers comprising a felted material. 
   
   
       5 . A gas compressor assembly as in any one of  claims 1 ,  2 ,  3 , or  4  wherein the compressor is a multi-stage compressor having a piston rod for each stage and penetrations in the dust control enclosure for each piston rod. 
   
   
       6 . A gas compressor assembly as a  claim 5  wherein the crank mechanism comprises two or more Scotch yokes connected to a shaft extending into the crank case cavity. 
   
   
       7 . A gas compressor assembly as a  claim 6  wherein the compressor is a four stage compressor having pairs of opposed, linearly reciprocating, pistons.