Bellows pump with flexible partition membrane

Abstract

It is sought to provide a small-size and highly safe bellows pump dealing with an explosive gas or the like as pump feed fluid, which can prevent hazards due to reaching of a drive motor or like drive part by the pump feed fluid caused to leak out when the bellows is broken. A flexible partition membrane is stretched between the movable end of the bellows and the pump housing to make the outside-bellows region to be a sealed chamber. The flexible partition membrane can follow the reciprocation of the bellows and does not interfere with the operation thereof. When the pump feed fluid leaks out from the pump chamber due to breakage of the bellows during operation thereof, it is retained in the sealed outside-bellows region, and does not reach the drive part including the drive motor. Also, the flexible partition membrane prevents dust intrusion to the bellows side, thus preventing such troubles as the breakage of the bellows otherwise stemming from the dust intrusion.

What is claimed is:  
     
         1 . A bellows pump comprising: 
 a pump head having an intake and a discharge port for passing pump feed fluid therethrough;    a cylindrical pump housing secured to the pump head;    a bellows capable of being elongated and contracted, which is accommodated in the pump housing to define a pump chamber therein, and has a secured end communicating the intake and discharge ports of the pump head via uni-directional valves, respectively, and a movable end capable of being reciprocated in a pump operation;    bellows drive means coupled via the movable end of the bellows to a crank mechanism and serving to cause reciprocation of the bellows in the pump operation;    a flexible partition membrane stretched between the movable end of the bellows and the housing and capable of following the reciprocation of the movable end; and    a sealed chamber formed in an outside-bellows region defined on the outside of the bellows between the bellows and the housing.    
     
     
         2 . The bellows pump according to  claim 1 , which further comprises: 
 a volume limiting member disposed in the pump chamber for limiting the pump chamber volume of the bellows pump; and    a retainer mounted on the movable end of the bellows for holding the volume limiting member;    said flexible partition membrane having one peripheral end part clamped between the retainer and the movable end of the bellows.    
     
     
         3 . The bellows pump according to  claim 2 , wherein said flexible partition membrane is constituted by a diaphragm.  
     
     
         4 . The bellows pump according to  claim 3 , which is an air pump for pumping such gas as explosive gases as the pump feed fluid.