GB1428654A - Gear pumps - Google Patents

Abstract

1428654 Rotary positive-displacement fluidmachines RENOLD Ltd 23 May 1973 [25 Feb 1972] 8764/72 Heading F1F To reduce leakage between high and low pressure zones 89, 90 in a reversible gear-pump, or motor, an insert 81 accomodating the gears 71, 72 is held against the tooth tips on the high-pressure side by e.g. the pressures in said zones being transmitted to spaces interjacent the insert and members 110, 111 through passages 115, 116, which may contain flow restrictors (R), Fig. 10 (not shown), to reduce the rate of response to sudden pressure changes. The insert may also be clamped between a plate 92 and a block 65 owing transmission of the pressures in the zones 89, 90 to spaces behind the plate through holes 95, 96. Recesses 101, 102 may contain sealing rings 97, 98 and plates 99, 100 with holes 104, 105 that are larger than the holes 95, 96. The plate may comprise a layer of plastics material such as nylon, acetal or polyvinylidene fluoride, backed with annular plates (92a), Fig. 6 and 7 (not shown). Fluid leaking from the high-pressure zone 89, or 90, between the insert 81 and block 65 is returned to the low-pressure zone by way of grooves 120, 120a in the insert. Additional plates similar to the plates 92, 99, 100 may be disposed between the insert and block, Fig. 10 (not shown).