GB745172A - Improvements in or relating to temperature control arrangements for rotary machines - Google Patents

Abstract

745,172. Lubricating; heating bearings. POWER JETS (RESEARCH & DEVELOPMENT), Ltd. June 29, 1954 [July 8, 1953], No. 18998/53. Classes 12 (1) and 12 (3). [Also in Group XXVI] A rotary machine having a flow path therethrough for a low-temperature fluid has a temperature-control arrangement comprising means for imparting heat to a bearing or other part of the machine, the means being operated when the speed has fallen to or below a predetermined value, to counteract at least partly the loss of frictional heating caused by the restriction of rotational speed. The heat may be imparted by lubricating fluid the supply of which is increased automatically on reduction of the speed of rotation of the machine. As shown, a turbine rotor 1 rotates in bearings 2 supplied with lubricating oil which is taken from a sump 5 by a pump 4 and delivered to ducts 3 after passing a spring- loaded valve 6 of an overspeed and oil-pressure control mechanism 7 similar to that described in Specification 730,296, [Group XXVI]. Each duct 3 has branches 8 containing spring-loaded ball valves 9. On one end of the turbine shaft is an impeller 12 supplied with oil through a pipe 13 and an automatic by-pass valve 14 from a duct 15 supplied under control of the valve 6. The pipe 13 normally supplies an excess of oil to the impeller, some oil being returned to the sump 5 through pipe 16. The impeller pumps oil through pipe 17 to the valve 14. The pipe 17 has a branch leading to a trip valve 19 of the control mechanism 7, the trip valve 19 operating the control valve 6 by means of a lever 21. The valve 14 comprises a housing 22 containing a plunger 23 which is spring-pressed downwardly and which has a helical groove 28 giving an unrestricted flow between the duct 15 and the pipe 13 when the plunger 23 is in its upper position. When the plunger is in the lower position the flow of oil is restricted. The degree of restriction may be varied by rotation of the plunger in its housing. When the turbine 10 is operating at normal speed oil is supplied to the bearings through ducts 3 and the branches 8 are closed by the ball valves 9. The oil supplied through pipe 17 by the impeller 12 is at sufficient pressure to hold the plunger 23 in its upper position. When the speed of the turbine is reduced the pressure in pipe 17 is reduced, and the plunger 23 moves down and restricts flow through the valve 14, causing an increase in pressure in the duct 15 and also in the ducts 3, and branches 8, so that the ball valves 9 are opened, resulting in an increased flow of oil and therefore additional heat to the bearings. If more heat is required an electrical immersion heater may be provided in the sump 5. On overspeed the pressure in pipe 17 will be increased whereby trip valve 19 will be operated causing the mechanism 7 to control the turbine as described in Specification 730,296, [Group XXVI]. In an alternative arrangement the bearings instead of receiving increased heat by increased oil are heated by one or more electrical heating elements switched on when the plunger 23 is in its lower position, the branched ducts 8 and ball valves 9 being dispensed with.