GB781950A - Improvements in and relating to variable-capacity pumps - Google Patents

Abstract

781,950. Rotary pumps. PLENTY & SON, Ltd. Nov. 17, 1955 [Nov. 17, 1954], No. 33329/54. Class 110 (2). A variable-capacity pump has a pressuresensitive device connected to the delivery side which regulates the pump delivery and prevents over-loading the pump driving-motor. The capacity is lowered when the delivery pressure rises unduly. In Fig. 1 a sliding-vane pump has an eccentric rotor 12 within an outer rotor 18 and the pump capacity is varied by altering the eccentricity through a vertical movement of a spindle 10, which is attached to an outer cage 20. Pressure in the delivery port 26 acts, through a pipe 36, on a piston 32, whose downward movement is resisted by a spring 38. The cage can be moved by means of a hand wheel 42. The bottom of the cylinder 30 may be vented to the suction port 24 through a pipe 88. A labyrinth packing groove 28 is provided for the spindle. In Fig. 2 the pump delivery pressure acts on the upper surface of a piston 46, the movement of which actuates a cam 58, pivoted at 60, to move a beam 62 which actuates one of the switches 66, 68. These switches are connected to a reversible electric motor 70 which has a worm-drive connection 72 with the capacity-adjusting spindle 54 of the pump. An increase in the capacity of the pump may be achieved by closing a switch 74, located near the pump, or by closing a remote switch 76. A decrease in the pump capacity may be obtained by closing either switch 78 or 80, to actuate the motor 70. If the pump delivery pressure rises beyond a predetermined figure, the piston 46 moves downward and the beam 62 closes the switch 68 in the motor circuit, and the worm-gear 72 is driven to actuate the spindle 54. Limit safety switches 82, 84 are provided. Any fluid leaking to the bottom of the cylinder 30 is removed by the drain pipe 88.