GB1121101A - Improvements in rotary pumps and motors - Google Patents

Abstract

1,121,101. Gear pumps and motors. ROBERT BOSCH, G.m.b.H. Aug. 9, 1965 [Aug. 8, 1964], No. 33957/65. Heading F1F. A reversible pressure-loaded gear pump, or motor, includes two externally-meshing gears 14, 15, Fig. 1, lodged between a pair of axially movable bearing-bodies 12, 13 that are pressed against the sides of the gears by pressure communicated to a plurality of chambers 62-65, Fig. 3a, from the high-pressure side of the meshing gear-teeth, the said chambers being defined by sealing ring or element 53, an end wall 33 of a housing 10 for the gears, and an axially-movable plate 24 abutting the body 12. The ring 53 is situated in a groove within the wall 33 and shaped so as to include radially -projecting portions or bulges 55--58 that overlap the adjacent end face of the housing 10, these bulges being in register with axial bands or lines of contact 11a, or 11b, between the bodies 12, 13 and the inner peripheral surface of said housing, which lines of contact are due to the pressure-gradient across the gears. A further end wall 31 of the housing 10 contains inlet and outlet passages or bores (44, 45), Fig. 2 (not shown) for the working fluid, which bores are in axial alignment with recesses (46, 47) situated within the said inner peripheral surface of the housing in register and communication with both the intermeshing gear teeth and the chambers 62, 63. Owing to radial displacement of the bodies 12, 13 and the plate 24 towards the low-pressure side of the gears as a consequence of the pressuregradient aforesaid, high-pressure working-fluid in the chamber 62, or 63, enters the chambers 64, 65 through narrow gaps between the plate 24 and the inner-peripheral surface of the housing 10. The pressure in the latter said chambers may be less than that of the high-pressure working-fluid in the adjacent chamber 62 or 63 due to leakage of said fluid into the gear-tooth spaces through said gaps and similar ones between the bearing-body 12 and the beforementioned surface. Working fluid leaking across the ring 53 into a further chamber 61 escapes through a bore 25 in the plate 24, an axial bore 26 in a shaft 17 supporting the gear 15, a bore 41 in the wall 31, and a union 39, the latter being also connected to annular grooves 34, 35 in the end faces of the central part of the housing 10 to facilitate removal of fluid leaking thereacross. The ring 53 may be replaced by a ring (53'), Fig. 3b (not shown), which has a configuration differing somewhat from that of the ring 53, chiefly in respect of the bulges therein. Friction at the lines of contact 11a, 11b may be reduced by portions of P. T. F. E. lodged in the aforementioned surface. Another embodiment, Figs. 4 to 7<SP>a</SP> (not shown), differs from that shown in Figs. 1 and 3a mainly in that chambers (162--165) similar to the chambers 62--65 are formed by a sealing ring or element (153) resembling the ring 53, which ring is lodged in an end wall (131) of the housing in abutment with a plate (124) that is substantially identical to the plate 24, the said end wall being furnished with inlet and outlet bores (142, 143) for the working fluid. A groove (121) and an aperture (125) in the plate (124) permit leakage fluid to escape from a chamber (161), which is similar to the chamber 61, to the low pressure side of the gears, the plate being reversible to allow operation of the pump or motor in either direction. The ring (153) may be replaced by a pair of D-shaped rings (166, 167), Fig. 7b (not shown). Another embodiment comprises a pair of internally-meshing gears 213, 214, Fig. 9, which are situated between and supported by two axiallymovable bearing bodies (218, 219), Fig. 8 (not shown), chambers 241, 242, 243 being formed by a pair of D-shaped sealing rings or elements 237, 238 lodged in an end wall or plate 211 of the housing in contact with an axially-movable circular plate (224) adjacent the bearing-body (219). The said elements intersect the profile 224' of the plate (224) and surround inlet and outlet bores 229, 230 for the working fluid, which bores are formed in the plate 211. Intersection of said profile by said rings occurs at points aligned with lines of contact 211a, 211b between said bodies and the inner peripheral surface of the housing. The plate 24, (124) or (224) may be dispensed with so that the associated sealing rings or elements directly engage with the adjacent bearing body.