Patent GB-280756-A (GB)
Title: Improvements in lubricating, sealing and thrust balancing means for compressors and the like
IPC: F04D29/04
Filed: 1927-02-15
Abstract: 280,756. Carrier, W. H., and Carrier Engineering Corporation. Feb. 15, 1927. Leakage-preventing devices; balancing moving parts.-In a centrifugal compressor or vacuum pump wherein oil is supplied by a pump for lubricating the shaft bearings and for sealing the opening in the casing through which the shaft passes, the oil returns to the pump through a separating chamber communicating with the suction side of the compressor, whereby gas or vapour is separated from the oil. The bearing 16, Fig. 1, at the suction side of the compressor is enclosed in a housing 18 forming part of the machine casing 10, while the bearing 17, Fig. 2, at the discharge side of the compressor is located outside the compressor casing, the thrust on the shaft 11 being towards the suction side. A pump 51 arranged in an oil chamber 50 in the base of the housing 18 and driven by gearing 51<b> from the shaft 11 supplies oil through pipes 52, 53 to a thrust balancing chamber 54, Fig. 1, and to an oil reservoir 24, Fig. 2. From the chamber 24, oil passes through a pipe 25 and passages 26, 21<a >to an oil sealing chamber 20 formed in a casing 21 secured to the casing 10. Secured on the shaft 11 and located within the chamber 20 is a disc 22 which, during the operation of the machine, is held out of contact with a ring 23 forming part of the casing 21. Part of the oil from the chamber 20 passes to the bearing 17, while another portion leaks past a loose stationary packing ring 30, which has lateral play in a cavity 30<a> in the casing 21, being removed from the shaft by packing 31 and passing through a passage 32 to a trap 33 provided with a floatactuated valve 34. Oil overflows from the bearing 17 through a pipe 37 to a trap 38. A separating chamber 40 in the housing 18 communicates through an opening 41 in its upper part with an adjoining chamber 42 communicating through packing 43 with the suction chamber of the compressor, whereby gases and vapours are drawn from the warm oil through the opening 41. Pipes 36, 39 from the traps 33, 38 discharge into the chambers 42, 40 respectively, oil passing from the chamber 42 to the chamber 40 through a hole 44 connecting the lower portions of the chambers. Oil is returned from the bearing 16 to the chamber 42 through an overflow 68 and a passage 69. From the chamber 40 the oil passes through an aperture 45, Fig. 3, to a chamber 46 provided with cooling means 47, and thence through an opening 49 to the pump chamber 50. The openings 41, 44, 49 are controlled by spring-pressed valves 70 operated by cams 72 on a rod 73 connected to a piston 74 subjected to the pump pressure, so that the chambers 40, 46, 50 are closed when the machine is inoperative. The chamber 24 is provided with a ball valve 84 which is seated by the oil rising in the chamber but which opens when the machine stops, to prevent the formation of a vacuum in the chamber. A hollow piston 55 slidable on the shaft 11 in a cylindrical portion 56 of the chamber 54 is pressed outwardly by a spring 58. The outer end of the piston has an opening 59 adapted to be closed by a spring- pressed valve 60 mounted on a headed stud 61. Secured on the shaft within the piston is a disc 63, the inner side of which is adapted to engage the inner end wall of the piston. When the machine is inoperative, the spring 58 moves the piston to the left and the valve 60 close the opening 59. When the machine is started, the oil in the chamber 54 forces the piston to the right, the valve 60 moving therewith until its movement is arrested by the stud 61. The piston continues its movement until arrested by a shoulder 65, and oil entering the piston acts on the disc 63 to balance the thrust of the shaft. Oil passing through the clearance between the disc 63 and the outer end of the piston escapes through a hole 66 provided with a spring-loaded valve 66a and passes through a pipe 67 to the bearing 16. The movement of the piston to the left when the machine is shut down produces a corresponding movement of the shaft 11, causing the disc 22 to seat against the ring 23, completely closing the shaft opening in the casing 10. A hand. device 80 is provided for testing this closure, comprising a screwed or cam ring adapted to turn in a member 81 and engaging a collar 82 on the shaft. When the machine is in operation, the movement of the disc 63 causes the disc 22 to move away from the ring 23.