Internal recirculation for magnetically coupled positive displacement pumps

Abstract

A magnetically coupled positive displacement pump with a metallic containment can has high and low pressure port passageways through a flange of the pump which provide communication between the interior of the can and the pumping cavity of the pump to remove heat generated by eddy currents in the can. Either or both of the port passageways can be provided with a removable or otherwise adjustable orifice which allows easy modification of cooling fluid flow rate for improved heat removal to more closely meet the needs of a given application. The invention provides an orifice controlled recirculation rate through the can, easy modification to change the recirculation rate and/or adapt the pump to various fluid properties and improved recirculation performance to expand the application base of the associated pump.

We claim:  
     
         1 . In a positive displacement pump driven by a magnetic coupling including a containment can enclosing in an interior thereof a driven magnet mounted on a pump drive shaft and a driving magnet exterior of the can, the driving magnet being magnetically coupled to the driven magnet, the pump also having a high pressure port, a low pressure port and a positive displacement pumping mechanism in a pumping cavity between the ports, and having a pump flange between the driven magnet and the pumping cavity, the improvement wherein two port passageways extend through the pump flange between the interior of the containment can and the pumping cavity, at least one of said port passageways includes an orifice of an orifice size and the orifice size is adjustable.  
     
     
         2 . The improvement of  claim 1 , wherein there is at least one said port passageway in communication with each of said high and low pressure ports.  
     
     
         3 . The improvement of  claim 1 , wherein said orifice is replaceable with an orifice of a different orifice size so as to adjust the orifice size.  
     
     
         4 . The improvement of  claim 1 , wherein said at least one port passageway including an orifice provides communication through said pump flange between said low pressure port and said interior of said containment can.  
     
     
         5 . The improvement of  claim 1 , wherein at least two port passageways extend through said pump flange between the interior of the containment can and the pumping cavity, at least one said port passageway communicating with each of said high pressure and low pressure ports, and wherein each said port passageway includes an orifice.  
     
     
         6 . The improvement of  claim 5 , wherein each said orifice is removable.