GB1243025A - Improvements in and relating to hydraulic gear pumps - Google Patents

Abstract

1,243,025. Rotary positive-displacement pumps. O. ECKERLE. Aug.27, 1968 [Sept.1, 1967], No.40847/68. Heading F1F. An hydraulic gear-type pump has a driving- shaft 3 with a pinion 2 meshing with an internallytoothed gear 4, which is pressed against the pinion and a filling piece 5 by a member 10 pivotally mounted on a pin 11 that has each end slidable in a corresponding recess 13 formed in the casing 1. To load the member 10 a recess 20 adjacent an outlet passage 9 is connected by bores 21 to spaces 22 associated with two annular pistons 18, which are biased outwardly by springs 24 and pressure transmitted through bores 19. A further piston 18 seals the passage 9. The piece 5 pivots on a pin 6. The thrust exerted by the fluid in the spaces 22 is partially counteracted by the pressure of fluid leaking from the recess 20 between the gear 4 and the member 10 towards grooves 25 communicating with an inlet passage 8. The gear 4 has radial bores (not shown) between the teeth to allow the working fluid to pass into and from the tooth spaces of this gear and the pinion. The central piston 18 may be replaced by a tubular plunger (29), Fig.3 (not shown). The other two pistons may be replaced by sheet-metal rings (35), Fig.4 (not shown). Alternatively, these pistons are replaced by pistons (43), Fig.6 (not shown), made of plastics material. As shown in Fig. 8 the member 10 may abut a plate 58 at each end of the casing. Each plate is supported by a pin 59 and allows the member to exert thrust on the gear 4 only in the region of the pinion so as to minimize wear at the outer edge of the piece 5. A recess 64 and a bore 67 in each plate effect pressure balancing. A peripheral portion 61 of each plate may be rendered flexible and resilient by a slot (71), Fig.10 (not shown). In another embodiment, Figs.11 to 14 (not shown), the member 10 is pivotally secured to the casing by a pin (74) having limited freedom of movement circumferentially relative to the gear 4 so as to compensate for wearing of the piece 5, which is pivotally supported by a pin with each end slidingly lodged in a respective plate (73) mounted on the shaft 3 between the gear and pinion and the adjacent end of the casing. Each plate has a bore (82) therein to provide pressure balancing. In a modification, Fig.15 (not shown), the piece 5 is attached to said plates by a pin (92) and abuts a pin (93) allowing limited movement of the piece relative to the axis of the shaft 3.