IMPROVEMENTS RELATING TO MECHANICAL SEALS

摘要

1282915 End-face seals F BURGMANN [trading as FEODOR BURGMANN JNR ASBEST-UND PACKUNGSWERK] 14 Aug 1969 [17 March 1969] 40582/69 Heading F2B A mechanical seal for a nuclear reactor pump comprises a pump device formed by external and internal screwthreads 15, 17 for circulating a cooling, lubricating or sealing medium to the sliding face, the screwthread rotatable with the shaft being of opposite hand to that of the screwthread associated with the shaft housing. As shown, a stationary seal ring 8a is urged by springs 14a into engagement with a seal ring 7b rotatable with the shaft, the carrier 3b for the rotary ring being provided with the external screwthread 15. The medium is discharged through an outlet 19 and passes through a heat exchanger before returning to an inlet 18. The face of either of the seal rings may be provided with arcuate grooves which extend from one point on the circumference to another. In a second embodiment, Fig. 2 (not shown), the ring (8b) rotatable with the shaft is spring- loaded towards the stationary ring (7a), the load being modified by the axial thrust generated by the pumping action. In a third embodiment Fig. 3 (not shown), two mechanical seals are' provided in series, the rotary seal rings (81b' 811b) of which are urged along the shaft in opposite directions towards the stationary rings and are surrounded by a single sleeve (23) containing the external screwthread (15); in this embodiment, the pressure of the medium is increased by means of a gas-charged container (22) in the circuit. In a fourth embodiment, Fig. 4 (not shown), two mechanical seals are provided and the carrier for each rotary ring is provided with an external screwthread. In a fifth embodiment, Fig. 5 (not shown), the spring for urging the rotary seal ring into engagement also serves as the external screwthread.