GB1157162A - Improvements in or relating to Hydraulic Vane Pumps - Google Patents

Abstract

1,157,162. Rotary positive-displacement pumps. ABEX CORP. Sept.26, 1966 [Sept. 27, 1965], No.42931/66. Heading F1F. In a hydraulic rotary positive-displacement pump of the outwardly-sliding radial vane type that is generally similar to the pump disclosed in Specification 1, 071, 097, damage to the inner surface 46, Fig. 3, of a cam ring 32 and cavitation in regions adjacent the trailing surfaces of the vanes 45 due to liquid leaking across the peripheries of said vanes while they are passing through each of two diametral-opposite "transfer zones" 48 between the cam ring and the rotor 42 is minimized by the provision of a path that allows the leakage liquid to by-pass the trailing edges 97, Fig. 6, of each of the vanes. The edges 97 of each vane together with the leading edges 101 thereof define a groove 84 in each of the lateral surfaces and the radially-outermost surface of the vane to effect equalization of pressures acting upon the vane in radial and axial directions relative to the rotor, the aforementioned path being constituted by a radial bore 98 and a relatively large bore 99 in the trailing side of the vane, which bores are connected to each other by a flow-restricting bore 100 so that the velocity of the liquid leaving the bore 99 is small enough to prevent the formation of gases in the liquid within the region adjacent said side. When each of the vanes is in a fully-retracted position, Fig. 5 (not shown), the bore 98 is obturated by the adjacent side of the slot within the rotor wherein the vane is lodged so that back-flow between outlet ports 77 and inlet ports 72 is prevented. In a second embodiment, Fig. 10, a pair of by-pass, or diversion, conduits 150, 151 are provided in a pressure-loaded check-plate 143 that abuts one side of the rotor, which conduits are situated in diametrally-opposite localities in radial alignment with the transfer zones 48 at a radial distance from the axis of rotation of the rotor equal to that of the radially-innermost portions 86 of the slots for the vanes whereby the leakage liquid can escape through orifices 153 and a bore 159 to the inlet side of the pump. In a third embodiment, Figs. 12 and 13 (not shown), the portions 86 of the slots are each connected to the region adjacent the trailing surface of the associated vane by bores (290, 291) in the rotor, the leakage liquid being thereby able to by-pass the trailing edge of the vane through said bores and the grooves in the lateral and radially-outermost surfaces of the vane. In a fourth embodiment, Figs. 14 and 15 (not shown), each vane has a single lip or edge in its radially-outermost surface and a radiallyorientated groove (384) in each of its lateral surfaces, this embodiment being otherwise similar to the third one. In a fifth embodiment. Figs. 16, 17 and 18 (not shown), bores (492, 493), which are similar to the bores (290, 291) in the third embodiment, are provided in the rotor such that they are shutoff by the vanes when the latter are fully-retracted so as to prevent back-flow as aforesaid, a notch (490) being provided in each vane to give the leakage liquid access to the bores when the vanes are in the transfer zone.