Patent GB-1048593-A (GB)
Title: Variable speed coupling
IPC: F16D33/16
Filed: 1964-03-02
Abstract: 1,048,593. Hydraulic couplings; change-speed control. FMC CORPORATION. March 2, 1964 [March 11,1963], No. 8786/64. Headings F2C and F2D. [Also in Divisions F1 and G3] A fluid coupling F, Fig. 2, between an electric motor M and a centrifugal pump P, is provided with bleed holes 32 through which its working liquid is returned to a sump 10, a flow-dividing shoot 150 or the like variably controlling the volume of liquid supplied from a make-up pump 122 into a funnel 90 feeding the coupling and hence the slip in the latter. The shoot 150, Fig. 5 (not shown), comprises two angled flow-pipes 152, 154, the former directing liquid into the coupling filling funnel 90 and the latter diverting liquid straight back to the sump 10. The shoot 150 is carried at the end of a lever 158, 184 mounted upon a pivot-pin 186; the shoot lies between an orificed plate 140, through which liquid is fed from the make-up 122, and the funnel 90. As the shoot 150 moves transversely across the orifice plate 140 with pivoting of the lever 158, 184, so the flowpipes 152, 154 adjust the volume of liquid fed to the coupling F. As shown, pivoting of the lever 158, 184 is effected by the pressure developed in the centrifugal pump P, fed through a pipe to an expansible bellows 160, Fig. 4 (not shown), to act against the bias of a spring 207 adjustably stressed by hand operation of a screw knob 200. If, e.g. the demand for water or gas, &c. supplied by the pump P decreases, the pressure in the pump increases and causes the bellows 160 to expand against the bias of the spring 207, thus turning the arm 158, 184 about its pivot 186 so that the shoot 150 moves to divert an increased volume of liquid from the make-up pump 122 straight back to the sump 10; slip in the coupling F then increases, and the pump P is therefore driven more slowly, allowing its internal pressure to fall. Alternatively, pressure in the bellows 160 may be controlled in dependence on differential pressures, constant speed, constant level in a tank &c. As shown, the orificed plate 140 is formed with a straight-sided slot 142 through which flows make-up liquid, and sensitivity of control response is effected by adjusting the angle of the slot relatively to the main gear axis. As modifications, the slot 142 may have cruved sides, Fig. 19 (not shown), or be of triangular cross-section, Fig. 20 (not shown). In a modified construction, the orificed plate is replaced by a rotatably-mounted flattened nozzle 228, Fig. 14 (not shown), and the co-operating shoot 150a has two flow-pipes 152a, 154a, the former directing liquid straight into the hub of a fluid coupling F1, Fig. 13 (not shown). In another modified construction, the flowdividing shoot is formed by the edge 232, Fig. 17 (not shown), of a funnel 230, Fig. 16 (not shown), leading into the hub of a coupling F2, a flattened nozzle 234 at the end of a pivotallymounted pipe 238, 242 moving across the funnel edge to control the slip in the coupling. In the form shown in Fig. 2, the coupling I has two impellers and two turbines, but in a modification, a coupling F3, Fig. 21 (not shown), employing a single impeller and turbine is illustrated, this coupling having a shroud 252 of such configuration as to modify the rate of response to pressure changes in the pump P, depending upon the level of the liquid within the coupling. The impeller and turbine are provided with interior ring-shaped guides and auxiliary blades 78, 80.