Dual reciprocating bellows pump with interlock shaft means

Abstract

It is sought to provide a dual reciprocating bellows pump having two, i.e., left and right, bellows interlocked by interlock shafts to each other, which is free of wear powder or wear dust generated by the frictional movement of the interlock shafts and bearings relative to one another from pump feed fluid in pumping chambers, permits ready use of synthetic resin as pump element material, is excellent in function and cost and readily permits size reduction design. Paired interlock shafts coupled to end members 6 of the pair of, i.e., left and right, bellows, are disposed in paired working air chambers 8, and are movably inserted in through bores provided in a pump head. Between each interlock shaft and each through elastic seal members are disposed, thus sealing the left and right working air chambers 8 from each other. No particular bearing is used for the interlock shafts. Lip seals are desirably used as the elastic seal members.

1 . A dual reciprocating bellows pump with interlock shaft means comprising; 
 a pump housing;    a pump head assembled in the pump housing at the center along a longitudinal axis thereof and capable of withdrawing and discharging pump feed liquid;    a pair of left and right cylindrical bellows having respective end parts sealedly mounted on the pump head and capable of expansively and contractably reciprocating with a predetermined stroke in the pump housing in longitudinal directions thereof;    paired end members each sealedly coupled to the free end of each bellows and capable of cooperating with the pump head defining pumping chambers inside the bellows and also defining working air chambers between the bellows and the housing;    paired interlock shafts as said interlock shaft means, each having the two ends coupled to the pair of end members such as to cause reciprocation of each bellows in an interlocked relation to the reciprocation of the other bellows, inserted through through bores formed in the pump head and capable of being displaced in the longitudinal directions of the pump housing;    working air feed means for selectively feeding working air to the pair of left and right working air chambers, and    paired valve means mounted on the pump head in correspondence to the pumping chambers, respectively, in the pair of left and right bellows reciprocated in response to pressure changes of working air fed by the working air feed means, for controlling the flow of the pump feed fluid into and out of the pumping chambers;    wherein:    said through bores formed in the pump head are open in the pair of left and right working air chambers;    said interlock shafts extend through said through bores into the pair of left and right working air chambers; and    seal means is provided between said interlock shaft and the corresponding through bore so as to isolate said left and right working air chambers.    
   
   
       2 . The dual reciprocating bellows pump with interlock shaft means according to  claim 1 , wherein: 
 said seal means includes a cylindrical guide member open at the two ends, inserted and secured in said through bore of the pump head and extending into the left and right working air chamber, and an elastic seal member mounted in said open ends of the guide member;    said interlock shaft is movably inserted in said corresponding cylindrical guide member, the inner diameter of the cylindrical guide member being greater than the outer diameter of said interlock shaft; and    said elastic seal member effects isolation of the left and right working air chambers in sealed contact with said corresponding interlock shaft.    
   
   
       3 . The dual reciprocating bellows pump with interlock shaft means according to  claim 1 , wherein: 
 said inner diameter of said through bore of the pump head is greater than the outer diameter of said interlock shaft; and    an elastic seal member is disposed in said corresponding through bores such as to be able to be in sealed contact with said interlock shaft, thereby effecting the isolation of the left and right working air chambers.    
   
   
       4 . The two-ganged interlock bellows pump with interlock shaft means according to  claim 3 , wherein; 
 said elastic seal member is constituted by a lip seal.    
   
   
       5 . The dual reciprocating bellows pump with interlock shaft means according to  claim 4 , wherein: 
 said pump constituent elements are all made of synthetic resin.