Patent GB-1022692-A (GB)
Title: Improvements in electrical machines having liquid cooled rotors
IPC: H02K9/193
Filed: 1963-03-08
Abstract: 1,022,692. Seals. LICENTIA PATENTVERWALTUNGS-G.m.b.H. March 8, 1963 [March 10, 1962; Aug. 1, 1962], No. 9359/63. Heading F2B. In a junction-box 1, Fig. 1, for the supply and/or removal of cooling liquid relative to the rotor 4 of an electrical machine, sealing means between the liquid flow path and the atmosphere includes a chamber 11 interposed between a first seal 9 subjected at its other side to the cooling liquid and a second seal 6A, 31 subjected at its other side to the atmosphere, cooling liquid leaking past the seal 9 being discharged from the chamber 11 through a drain pipe 24 so that it can be returned to the cooling liquid circuit. The box 1 is bolted to the housing 32 of the machine and is provided with inlet and outlet ports 3, 5 for purified cooling water which flows through tubular members 12, 13 fixed in the rotor 4 and a member 6 secured thereto, passes into the rotor and returns through an annular passage 15 into a collecting chamber 10 connected to the outlet port 5. The seal 9 is of the sleeve type and a similar seal is provided between the inlet and the chamber 11. A gaseous seal comprising comb-like ring seals 17, 18 separated by an annular chamber 19 is interposed between the chamber 11 and another chamber 16. The seal 6A, 31 is of the spring- urged rubbing collar type and is provided with lubricating oil which is allowed to leak into the chamber 16 and is removed through a drain pipe 27. A pressure regulator 29 influenced through a pipe 30 by the water pressure in the chamber 10 controls the pressure of nitrogen gas supplied to the chambers 11, 19 so that the pressure in chamber 11 is preferably lower than the water pressure in the chamber 10. Leakage of gas from the chambers 11, 16 through valvecontrolled pipes 22, 25 is permitted to create a gas flow from the chamber 19 through the seals 17, 18 so that leakage of cooling water and lubricating oil through the latter is prevented. In a first modification, Fig. 2 (not shown), the cooling water may be supplied at 3 and exhausted at 5 and there is arranged between the chambers 10 and 11 a balancing chamber 41 which is connected,with the water outlet port 5 by a line 42 which ensures that the chamber 41 is always maintained at the same pressure as the outlet port 5. If, however, port 5 is used as an inlet, a valve (not shown) in line 42 is closed to ensure that the pressure in chamber 41 corresponds to the lower pressure in the port 3 which in this case is the outlet port. In a second modification, Figs. 3 and 4 (not shown), an additional seal 51, which comes into operation when the rotor is at rest, is arranged in the region of the seal 9 between the chamber 11 and the chamber 10 of Fig. 1, as shown, or the balancing chamber of the first modification. The seal 51 is in the form of a metal-reinforced rubber bellows having a sealing flange 52 which, when the rotor is at rest, is pressed by springs 54 against a flange 55 on the member 6. In this position, a space behind the flexible membrane 61 of the bellows communicates with the gas chamber 11 through a bore 65. By increasing the water pressure in the chamber 10, the flange 52 is lifted from the flange 55 against the force of the springs 54 and allows cooling water to enter the space 68. A sealing lip 67 prevents water penetrating behind the membrane 61 which is subsequently deformed against the curved wall of the sealing sleeve 9. The cooling water is supplied from a tank 70 through a pump 71 which is either separately driven or has its impeller installed on the rotating member 6. In the latter case, the water pressure in the chamber 10 is increased to lift the stationary seal 51 before the starting of the electrical machine and this is achieved by increasing the pressure of a nitrogen gas cushion provided above the water level in the tank 70. When the machine is brought to rest, the stationary seal remains lifted until the gas pressure in the tank is reduced. When using a separately driven pump, the stationary seal lifts at once upon switching in the pump and the electrical machine is then started. When bringing the machine to rest, the seal is kept open until the member 6 comes to rest, the pump being then de-energized to close the seal.