Patent GB-1223179-A (GB)
Title: Pump shaft mechanical seal lubrication means
IPC: F04D29/12
Filed: 1968-12-24
Abstract: 1,223,179. Cooling pump shaft seals. BORGWARNER CORP. 24 Dec., 1968 [22 Jan., 1968], No. 61456/68. Heading F4U. [Also in Division F2] In a pump B having a rotary shaft 13 driven by a prime mover A and sealed by a mechanical seal comprising a rotary sealing ring 19 and a non-rotary sealing ring 29 in facial sealing contact and in which, during normal pump operation, liquid under pressure in the pump housing 10 is circulated around the seal to cool and lubricate it, an injection circuit is provided to supply liquid to the seal to lubricate the sealing faces 55, 56 during starting-up the pump, the circuit including control means which is automatically operated to open the circuit to supply liquid to the seal when the prime mover is started, and after a predetermined time when the pump is running at its normal working speed and the normal seal cooling and lubrication means is effective, is operated to close the circuit. The invention is described with reference to a centrifugal boiler feed pump B driven by a motor A and supplied with liquid under pressure from a condensate pump 86 or other source. The non- rotary ring 29 is mounted on a backing ring 30, held against rotation and urged axially by a bellows 38 into facial contact with the rotary ring 19 which is clamped between shaft sleeves 16 and 20 and keyed to the shaft 13. Labyrinth seal grooves 25 are formed on the sleeve 16. The bellows 38 is attached to the ring 30 and to an adapter 39 slidable in a flange 40 secured with a flange 37 to the housing 10. An inlet 47 and bore 48 in the flange 40 communicates with a bore 50 in the adapter 39 connected by a flexible pipe 51 to a bore 52 in ring 30 and bores 54 in the sealing ring 29 leading to the sealing faces 55, 56. The bore 50 is sealed by 0-rings 44 and 45 and the amount of bellows compression is adjustable by screws 46. During normal running of the pump, liquid under pressure in the housing 10 is circulated around the rings 19, 29 to cool and lubricate them by vanes 57 on the rotary ring 19, the liquid being discharged through bore 60 and conduit 65 to an external heat exchanger 64 where it is cooled and then returned through conduit 66 and bores 62 and 62Co to the seal chamber 67. The inlet 47 is connected to the conduit 66 by a branch conduit 69 including a solenoid valve 70 actuated by a timedelay relay 75 connected to the starter 78 for the motor A. A by-pass conduit 72 and valve 73 for the valve 70 may be provided. Any air trapped in the system is vented through valves 68 and 71 during initial filling by liquid under pressure from the pump 86 before starting the pump B. When the starter 78 is operated it actuates both the motor A and the relay 75. The latter opens the valve 70 and allows liquid under pressure to flow to the sealing faces 55, 56 to lubricate them through conduit 69, bores 48 and 50, pipe 51 and bores 52 and 54. After a predetermined time the relay 75 closes the valve 70, the sealing rings then being cooled and lubricated by liquid circulated by the vanes 57. A valve 74 may be fitted in the conduit 66 and in a modification, Figs. 3 and 4 (not shown), this valve (174) is incorporated in the motor starter system to ensure that the motor (A) cannot be actuated unless the valve (174) is open.