Patent GB-1040953-A (GB)
Title: Dry demounting of bearings of glandless pump without emptying the pump circuit
IPC: F04D15/00
Filed: 1963-07-02
Abstract: 1,040,953. Centrifugal pumps. H. MOSER. July 2, 1963 [July 4, 1962], No. 26278/63. Heading F1C. [Also in Division H2] In the central heating pump shown in Fig. 2, the driving motor comprises a stator core 6 having its windings 7 mounted in radial slots and embedded in cast resin. As shown in the upper half of Fig. 2, the motor rotor may comprise an iron disc 10 with a copper mantle 11, carried by the pump impeller 9. Alternatively, as shown in the lower half, the impeller 9 also forms the motor rotor and is made of cast iron, cast steel or a sintered mixture of copper and iron. The motor rotor is exposed to the liquid being pumped but the stator is isolated from it by a thin disc 8. A graphite bearing 14 is held within a bore in the impeller 9 by rubber rings 15 and co-operates with a stationary journal 16 and a stationary thrust disc 13. The journal 16 has an extension 12 by which it is secured, by means of a nut 17, to the motor casing 4, seals 19 being provided. Liquid is diverted from the pump outlet and passed through a pipe 20, the hollow extension 12, a filter 21 and a non- return valve 23 to lubricate the bearing 14. When the pipe 20 is removed, the non-return valve 23 closes to prevent leakage of liquid from the pump casing 1. The motor casing 4 has a bayonet-type connection to the pump casing 1 by means of lugs 5 which enter slots in a ring 3, see also Fig. 1a (not shown), and when the casing 4 is turned, engage behind cam faces provided between the slots. The consequential axial displacement of the impeller permits the pump output to be adjusted by turning the motor casing 4 backwards from the extreme position shown to increase the clearance between the impeller blades and the adjacent wall of the pump casing 1. When the motor casing 4, complete with stator 6, 7, is removed to gain access to the bearing, the pressure of the liquid in the pump casing 1 moves the impeller 9 to the left into sealing engagement with a rubber seal ring 2 whereby leakage from the pump casing is prevented. Fig. 3 shows a pump in which the motor casing 4 is bolted to the pump casing 1, access to the bearings being obtained by removing either the motor casing or an end cap 18 having a bayonet-type connection 3, 5 to the motor casing similar to that shown in Figs. 1a and 2. After removal of nut 17, the motor rotor 10, 11 and the bearing parts 12, 13, 14, 15 can be removed. In this embodiment, the rubber seal ring 2 is located in an annular slot in the impeller 9 and is deflected by the liquid pressure into sealing contact with an internal surface of the pump casing 1 without axial movement of the impeller necessarily occurring. The motor stator is isolated from the liquid being pumped by a cylindrical sleeve 8. Liquid for lubricating the bearings is diverted through a valve 24 and filter 21, passing thence through two separate paths to the bearings, and is returned to the main circuit by auxiliary blades at the back of the impeller 9. Adjustment of the clearance between the impeller blades and the pump casing, for the purpose of varying the pump output, can be effected by using an appropriate thickness of gasket between the pump casing and a removable end plate 1a. Additionally, this adjustment can be effected by means of the bayonet-type connection 3, 5 as in Fig. 2. In a further embodiment generally similar to that shown in Fig. 3, the seal ring 2 is stationary as in Fig. 2.