Centrifugal pump

The utility model relates to a water pump field, the utility model discloses a centrifugal pump, preceding closing cap (1) and back closing cap (2) lock form pump chamber (1 -2), machinery bearing seal (5) is including expansion ring (51), swivel becket (52), fixed loop (53) and fixed loop seat (54), the fixed loop seat can be dismantled with back closing cap rear side and be connected, impeller (10) and pivot (4) key -type connection, the expansion ring front end is fixed with the impeller buckle, the expansion ring rear end is fixed with the swivel becket buckle, swivel becket and fixed loop sliding seal, the fixed loop is fixed with fixed loop seat buckle, the expansion ring is passed in proper order in the pivot, the swivel becket, fixed loop and fixed loop seat are connected fixedly with motor shaft (31), temperature sensor (6) are inlayed and are inserted in the fixed loop, and level sensor (7) are used for detecting the liquid level in the pump chamber. This centrifugal pump can measure and control the frictional heat of dynamic seal face, avoids mechanical bearing seal and damages mechanical bearing seal because the frictional heat of dynamic seal face is too high to the operational situation of detectable motor.