GB511298A - Improvements in or relating to liquid pressure control systems - Google Patents

Abstract

511,298. Rotary pumps; hydraulic machines. AUTOMOTIVE PRODUCTS CO., Ltd., and CHOUINGS, L. C. Feb. 19, 1938, No. 5278. [Class 110 (ii)] [Also in Group XXIX] A reversible pump A is supplied with liquid by a reservoir B, and feeds either side of a slave E to move the piston in one or the other directions. When the pump is stationary, both flow and return passages 20, 21 are connected with the reservoir, and with each other by means of a large clearance between co-operating members in the pumping means. Fig. 1 shows a gear pump with a gear 15 rotated by a shaft 16 and driving a gear 14 mounted on a fixed spindle 17. A pipe 24 leads from the reservoir to a passage 25 which communicates with restricted openings 28, 29, allowing liquid into the casing. A relief opening 30 of V-shape also communicates with the passage 25, the limbs of the V being tangential with regard to the pitch circle of the gear 15. The teeth on the gears have substantial play and the clearance places the passages 20, 21, into communication with the reservoir B by way of the opening 30 while the pump is idle. During operation, the gears are in firm contact, and the opening 30 is isolated from the delivery passage 20 or 21. The gears are coated with rubber 38, or equivalent material, which may be vulcanised to shape. In a modification Fig. 4, a rubber, or the like, bush 44 is mounted within the gear 14, which fits loosely on the spindle 41. Holes 42, 43, allow liquid from the reservoir to pass inside the .bush 44 when the pump is idle, and the liquid to enter the pump through radial passages 45. During operation the bush 44 is pressed against the hole 43 and seals it. The holes 45, 43, lie in different planes. A further modification embodies three gears arranged in a tri-angular casing, the driven gears not being in contact with each other. The driving shaft may have a resilient device adapted to return the shaft through a small angle when the driving force is removed, to ensure clearances being left between each pair of rotors. Fig. 7 shows an eccentric rotor 60 having a pair of sliding vanes 62 spring-pressed apart. The reservoir B, communicates with co-axial openings 67 in the end walls of the casing and rotor. The vanes are a loose fit in the slot 61, but during rotation of the rotor they lag behind pressing against the near walls of the slot. The coating 68 of rubber or the like, is recessed at 69 to produce a lip 70 which is pressed against the wall of the slot 61 when subjected to pressure: A block 71 of rubber, or the like, presses on the rotor 60 having adjusting means 72 to take up wear on the block. Specification 465,410, [Group XXIX], is referred to.