Patent GB-844893-A (GB)
Title: Self-regulating rotary pumping mechanism
IPC: F04C2/107
Filed: 1957-12-20
Abstract: 844,893. Continuous discharge mixing apparatus. O'CONNOR, W. J. Dec. 20, 1957 [Dec. 28, 1956], No. 39617/57. Class 86. [Also in Group XXVI] Self-adjusting rotary pumping mechanism comprises 'intermeshing helical screws 29, 34, having a drive shaft 30 extending through a mixing bowl 13 and detachably connected to a spindle 33 housed in a sleeve 36 on which is a rack 37 in driving connection with an arcuate gear 48 through an idler pinion 41 whereby the rotor 29 may advance or retract automatically within the stator 34 to compensate for changes in the pump pressure. The driving motor 20 is supported by a column 14 within a cabinet 11, which houses the driving means for the shaft 30 and supports the bowl 13 from which viscous substances such as foodstuffs, pharmaceutics, or frit and slip mixtures as used in enamelling and pottery industries are conveyed by the pump to a discharge outlet 65. A rigid frame 16 secured to the column 14 has sleeves 17 in which can slide guide rods 18 connected to a platform 19 carrying the motor 20. A nut 21, Fig. 3, rigid with the platform 19 engages ah adjustment screw 22 universally coupled to a rod 23 controlled by a hand-wheel 25 on the cabinet 11. The armature shaft 26 of the motor is keyed to a variable diameter pulley 27 driving by means of a V-belt 28 a pulley 42 carried by the spindle 33. By returning the handwheel 25, the effective diameter of the pulley 27 is adjusted to vary the drive of the rotor 29. Rotor 29 is of non-yielding material, such as metal, while the stator 34 is preferably of resilient material such as neoprene, the rotor having a single helical thread and the stator two threads which are 180 degrees apart, the pitch circles of the rotor and stator threads being the same. Mixer blades 31 may be adjustably and detachably mounted on the shaft 30, which may be so connected by a flexible coupling 32 to the spindle 33 that lifting of the spindle lifts the shaft 30 to partly separate the stator and rotor or as illustrated the couplings may have an upper jaw resting on a lower jaw under the force tending to move the spindle downwardly. The gear 48 is fixed to a shaft 49 mounted in the frame 16 and projecting into a socket 50 at the end of a lever 51 extending through a counterweight 53 carried by an adjustment screw 55. Screw 55 is adjusted by means of a handwheel 59 mounted on a rod 57 universally coupled to the screw. If the pressure in outlet 65 rises beyond the limit determined by counterweight 53, rotor 29 backs out of the stator 34 sufficiently to reduce the pumping force and is returned by the weight 53 as the pressure falls. If the rotor reaches its extreme outward position, spindle 33 may operate a switch 47 in the hood 46 of the cabinet to disconnect the motor. Switch 47 may be replaced by an alarm bell or light switch. To overcome starting resistance either the speed of the rotor is increased by adjusting handwheel 25 or the pumping force is reduced by adjusting counterweight 53 until pumping is under way. By moving spindle 33 to its uppermost position the coupling 32 can be disengaged to remove shaft 30 and rotor 29 for cleaning purposes. In a modification, Fig. 4, the pump casing 76, having inlet and outlet ports 72, 74 respectively, is secured to a resilient stator 78 in which turns a rotor 79 of burnished metal, the rotor having an axial bore through which extends a rod 82 so connected to a drive shaft 87 that the rotor wobbles transversely as it rotates. The shaft 87, which is surrounded by a stuffing box 89 and packing held in place by a gland follower 90, is mounted in a roller thrust-bearing unit 94 which can slide in a chamber 91 to relieve the pump pressure. A bracket 105 on the chamber 91 supports a bell-crank lever 106 having an arm extending into an opening 108 in the unit 94, the second arm 109 carrying a counterweight 110 adjusted by means of a setscrew 111. In further embodiments the rotor is adapted to move axially without axial movement of the drive shaft, the rotor being splined to slide along a connecting rod when the pump pressure rises above a certain limit determined by the adjustment of a spring abutting the connecting rod. The rotor envelope may be conical and the stator interior may have a corresponding taper, so that the rotor may be adjusted forwardly to compensate for wear. Flexible tubes having a metal reinforcement which is perforated may be vulcanized in helical passages in the stator. Fluid such as water may be pumped through the tubes to press the stator radially outwards against the rotor as pumping gets under way. The tubes may also be used to circulate a coolant.