GB1427393A - Hydraulic vane pumps - Google Patents

Abstract

1427393 Rotary positive-displacement pumps ABEX CORP 13 April 1973 [10 May 1972] 17996/73 Heading F1F Separation of each vane 32 from the inner end portion of an inwardly inclined ramp 67 of a cam surface 34 is prevented in an hydraulic pump which comprises restriction means 77, 78 which create a pressure differential between the radially inner and outer edges of each vane so as to urge the vane against the cam, and relief means 58 for relieving the pressure under each vane when the vane engages the central part of ramp 67. Each vane 32 has two sets of restriction means each comprising a restricted orifice 78 at the inner end of the vane the orifice being connected to a groove 63 at the outer end of the vane by a wider passage 77. In use, fluid is drawn into the slot beneath the vane through a suction port 45 in a cheek plate 10, Fig. 2, and this fluid is pressurized by inward movement of the vane when the latter engages ramp 67. This causes fluid to be forced through orifice 78 and create a higher pressure beneath the vane than outwardly of it. This maintains the vane in contact with the cam. To prevent this pressure from producing wear at the central part of the ramp 67 the pressure is relieved through an outlet port 58 in cheek plate 10 which registers with the rounded inner end of each vane slot.