GB968998A - Variable delivery gear pumps - Google Patents

Abstract

968,998. Gear pumps. W. REINERS, and G. WIGGERMANN, [trading as REINERS & WIGGERMANN, GETRIEBE-UND MASCHINENBAU]. Oct. 3, 1960, No. 33824/60. Heading F1F. A housing for a gearwheel pump comprising three intermeshing gear wheels having their axes substantially in a common plane and the intermediate wheel adjustable with respect to the outer wheels to vary pump delivery, comprises a two-part housing constructed contiguously around the outer two gear wheels so that only the intermediate wheel is surrounded by an annular hollow space guiding the idle streams of fluid flowing tangentially and in opposite directions around this wheel. As shown in Figs. 1 and 2, the housing parts 1a, 1b are equally recessed so that the partition plane lies substantially in the mid-plane of gear wheels 2, 3, 4 to produce symmetrical loading on the two housing halves and hence lighter construction of the housing and its fastenings. The wheel 2 is keyed to a driving shaft 6, the wheel 4 freely mounted on a distance bolt 17 and the wheel 3 mounted on an eccentric shaft 9 through which passes with clearance a fixing bolt 8 screwed into a cover disc 10 and securing a thrust-cap 11. The cap 11 is held against rotation by a pin 13 and groove 12 and formed with a recess 16 limiting the movement of a lever 15 adjusting the position of the wheel 3 within a range in which the axial distance between it and the driven wheel 2 is always equal to or greater than the distance between it and the outer free wheel 4. The housing parts are identical so that the lever 15 and the projecting end of the driving shaft 6 may be located on the most convenient side of the housing. Fastening bolts 22, Fig. 3, may be reduced in number from 11 to 8 by fitting them closely adjacent the gear wheels, with two of the bolts securing elbow bends 25 over the supply and discharge bores 7a, 7b. Alternatively the housing parts 1a, 1b may have unequal recesses, so that two shallow recessed parts or two deep recessed parts or one shallow and one deep recessed parts may be connected together to accommodate gear wheels of three different widths without increasing the number of patterns required in the manufacture of the housing. A relief valve housing 24, Fig. 7, may be connected to the housing by the same bolts 22 which connect the elbows 25 to the housing. The width of the housing adjacent the intermediate wheel may be reduced by the machining of annular depressions 21, Fig. 4, in the housing halves and these depressions in association with arcuate depressions 28 surrounding the wheels 2, 4 and extending for an angle # beyond the central axis X result in a reduction in frictional losses and in the heating of the pumped medium. Shaping of the depressions 21 in the region of the intermeshing points as shown in Fig. 4, together with the tooth gaps provides more gentle compression and expansion of the pumped medium with a consequent reduction in noise. Radial grooves 32 permit positive lubrication of the gear-wheels.