GB1137908A - Improved internal gear pump - Google Patents

Abstract

1,137,908. Internally-meshing gear pumps. STOTHERT & PITT Ltd. March 21, 1967 [Dec. 21, 1965], No.54072/65. Heading F1F. An internally-meshing gear pump comprising a casing 21, Figs. 1, 2, having inlet and outlet ports 24, 25, an outer rotor 32 driven by a shaft 35 having inwardly directed teeth 33 in mesh with outwardly directed teeth 41 of an inner rotor 40 eccentric with respect to the outer rotor and freely mounted on a shaft 43 and a liner 27 having openings 29 coinciding with the ports 24, 25 and diametrically opposite tongues 30 separating the ports 24, 25 from each other, includes means whereby the position of eccentricity of the inner rotor relative to the outer rotor may be varied to vary pump output and reverse the direction of flow through the pump. The means comprise a handle 45 secured to a portion of the shaft 43 concentric with the driving shaft 35 and turnable either manually or by a servomotor through 180 degrees. In Fig. 3, the handle 45 is positioned in which the minimum volume pocket between the rotors is at 6 o'clock and the maximum volume pocket at 12 o'clock and flow through the pump is then a maximum from right to left. On anti-clockwise rotation of the handle 45 through 90 degrees pump output is gradually reduced to zero. On further anti-clockwise rotation through 90 degrees pump output gradually increases from zero to a maximum in the opposite direction. To relieve pressure in the pump pockets adjacent the tongues 30, a circular recess 46, Fig. 6, having pairs of diametrically opposite radial grooves 47, 48 is formed in and end cover 23. A plate 49 having a pair of oppositely disposed radial lugs 50 fixed to the shaft 43 co-operates with the grooves 47, 48. The grooves 47 are less in width than the grooves 48 whilst the lug 50 is greater in width than the grooves 47 and lesser in width than the grooves 48 so that at maximum pump output when relief is unnecessary the lugs 50 mask the grooves 47 to isolate the pump pockets from the ports 24, 25 and at lower pump outputs the pockets adjacent the tongues are connected with the ports 24, 25 through a recess 46. Other constructions of relief means are described.