GB778523A - Fluid gear pump or motor - Google Patents

Abstract

778,523. Gear pumps and motors. ROPER CORPORATION, G. D. Jan. 18, 1956, No. 1727/56. Class 110 (2). The pump (or motor) comprises an even number of gears such as 23 ... 26 in meshing arrangement, power-transmission means 21 connected to one of the gear shafts, and rollers 28 ... 34 on gear shafts in rolling engagement with the rollers on two adjacent shafts to take up the radial thrusts on the gears and provide radial bearings for the shafts. High-pressure areas are provided over substantial arcs of the gear peripheries to thrust each gear inwardly. Bearing- plates 36, 41 are also subjected to fluid under pressure to press them against the sides of the gears for sealing purposes. In Figs 1 and 2 a pump is provided with spaced end-plates 11, 12 and a housing 13 containing inlet and delivery ports 17, 18; 15, 16, the working chamber 19 containing four meshing gears 23 ... 26. The driving gear 23 is mounted on a hollow shaft 27 coupled to the driving-shaft 21. Cylindrical steel rollers 28, 29 are keyed to the shaft 21 and the other gear shafts have similar rollers 30, 31 keyed to them. The rollers on each side of the gears are in contact, each having an outside diameter equal to the pitch diameter of a gear. The rollers are contained within bearing-plates 36, 41 which bear against the sides of the gears. Snap-rings 42 locate the rollers on their shafts. Passages 44, 45 are cut away in the housing to connect with the discharge ports 16, 15. The bearing- plates 36, 41 are pressed against the sides of the gears by fluid under pressure. Fig. 6 (not shown), illustrates a six-gear pump or motor with similar rollers and bearing-plates. Fig. 7 shows another arrangement in which two sets of four gears 81, 82 are provided on opposite sides of central rollers 83, 84. Figs. 8-14 (9 and 11 ... 14, not shown) cover another embodiment with four gears 121 . . . 124 on shafts 125 ... 128. A pair of wear-plates 135, 136, slidable in the casing 100, engage the side faces of the gears and have bores to receive the shafts. Wear linings 137 may be provided on the plates and linings to the shaft bores also. Preferably the diameter of each roller is made slightly greater than the pitch diameter of a gear so that when the gears are subjected to radial pressure, they will mesh properly. The rollers may each be provided with a crown so that they will not have only line contact along an edge, when the shafts deflect slightly. Ring members 151, 155 engage wear-plates 136, 135 and the member 155 is provided with sealing- rings 157, 158. Notches 170 allow free flow of fluid from the working chambers between the members 151, 155 and the adjacent wear-plates 136, 135 respectively. The notches also provide spaces for the insertion of a tool when the rollers are to be removed. The pressures acting on the sides of the wear-plates remote from the gears are substantially equal to inlet pressure, while the pressure acting on the gear face side of the wear-plates varies from inlet pressure to discharge pressure. Discharge pressure acts outside pistons 156. Lubrication and cooling of the gear end-faces and shafts is secured through the forcing of fluid through grooves 125c ... 128c in the wear-plates. A plug 185 is provided to form a partial running seal with the tips of the gear teeth, internally of the gear assembly, and prevents unrestricted flow between the alternate high and low-pressure areas.