Submersible motor-pump unit

Claim 1

IN A SUBMERSIBLE MOTOR-PUMP UNIT OF THE TYPE THAT INCLUDES A DRY TYPE MOTOR ELEMENT DISPOSED IN A PROTECTIVE HOUSING AND HAVING A DRIVE SHAFT PROJECTING THROUGH END WALL STRUCTURE OF SAID HOUSING AND A PUMP ELEMENT HAVING A PUMP HOUSING PROVIDING A PUMP CHAMBER, SEAL WELL WALL STRUCTURE SPANNING SAID PUMP CHAMBER AND PROVIDING A SEAL WELL THROUGH WHICH THE DRIVE SHAFT EXTENDS, AND AN IMPELLER DISPOSED IN SAID PUMP CHAMBER AND SECURED ON SAID DRIVE SHAFT, SAID PUMP HOUSING HAVING AN INTAKE PASSAGE ADAPTED TO COMMUNICATE WITH LIQUID IN WHICH THE UNIT IS SUBMERGED, SAID INTAKE PASSAGE LEADING INTO SAID IMPELLER, AND SAID PUMP HOUSING PROVIDING A DISCHARGE OUTLET PASSAGE LEADING FROM SAID PUMP CHAMBER, A FIRST ROTARY SHAFT SEAL ASSEMBLY DISPOSED IN SAID SEAL WELL TO PROVIDE A SEAL BETWEEN THE SHAFT AND THE SEAL WELL WALL STRUCTURE, INTERMEDIATE WALL STRUCTURE ENGAGED BETWEEN SAID MOTOR HOUSING AND SAID PUMP HOUSING TO PROVIDE A LUBRICANT CHAMBER THEREBETWEEN, AND HAVING A NORMAL LIQUID LEVEL TO DEFINE A GAS POCKET WITHIN AN UPPER REGION OF SAID LUBRICANT CHAMBER, A SECOND ROTARY SHAFT SEAL ASSEMBLY DISPOSED IN SAID LUBRICANT CHAMBER AT A REGION THEREOF OVERLYING MUCH OF THE VOLUME OF SAID GAS POCKET, AND MEANS MOUNTED IN SAID LUBRICANT CHAMBER AND RESPONSIVE TO ROTATION OF SAID SHAFT TO SUPPLY LUBRICANT TO SAID SECOND SEAL ASSEMBLY DURING OPERATION OF SAID UNIT.