Means for preventing or limiting interchange of liquids between communicating vessels

Claim 1

A SUBMERSIBLE ELECTRIC MOTOR AND PUMP ASSEMBLAGE FOR PUMPING LIQUID, SAID ASSEMBLAGE COMPRISING A HOUSING INCLUDING A PUMP CHAMBER, A MOTOR CHAMBER AND A TUBULAR NECK PORTION JOINING THE PUMP CHAMBER AND THE MOTOR CHAMBER, A ROTARY PUMP WITHIN THE PUMP CHAMBER AND AN ELECTRIC MOTOR WITHIN THE MOTOR CHAMBER, SAID MOTOR HAVING A DRIVE SHAFT EXTENDING THROUGH SAID NECK PORTION WITH CLEARANCE TO DEFINE AN ANNULAR PASSAGE CONNECTING THE TWO CHAMBERS AND COUPLED TO THE PUMP FOR ROTATING THE SAME, SAID PUMP CHAMBER HAVING AN INLET AND AN OUTLET FOR LIQUID TO BE PUMPED, THE LIQUID FLOODING BOTH CHAMBERS AND THE ANNULAR PASSAGE IN THE SUBMERSED CONDITION OF THE ASSEMBLAGE, AND A LABYRINTH MEANS ADJACENT TO ONE END OF SAID ANNULAR PASSAGE, SAID LABYRINTH MEANS INHIBITING AN UPWARD FLOW OF CONVECTION CURRENTS FROM THE PUMP CHAMBER TOWARDS THE MOTOR CHAMBER BY CONSTRAINING SAID CURRENT TO FLOW ALONG A TORTUOUS PATH EXPOSING THE SAME TO A COOLING ACTION BY LIQUID IN THE MOTOR CHAMBER PRIOR TO ENTERING SAID MOTOR CHAMBER.