US2055587A - Pump - Google Patents

Description

Sept. 29., 1936.

R. J. S. PIGOTT PUMP Filed Oct. 11, 1935 3 Sheets-Sheet l WW QN QM W ay x M Gnom u Sept. 29, 1936 J 5 PIGQTT 7 2,055,587

PUMP

Filed Oct. 11, 1955 5 Sheets-Sheet 2 gwu cwim Sept. 29, 1936. 5 PIGQTT 2,055,587

PUMP

Filed Oct. 11, 1935 3 Sheets-Sheet 3 F- J5. P gyo t MSW/W Patented Sept. 29, 1936 UNITED STATES PATENT OFFICE PUMP Reginald J. S. Pigott, Pittsburgh, Pa., assignor to Gulf Research & Development Company, Pittsburgh, Pa., a corporation of Delaware Application October 11, 1935, Serial No. 44 ,626 1 Claim. (Cl. 103-5) This invention relates to pumps; and it comenough to reduce the pressure on the liquid beprises in combination with a pump of the rotary low saturation point or vaporizationpoint, and positive displacement type adapted to pump liqgas is suddenly evolved from the liquid in the uids and having two interengaging main pressure suction side of the pump. The amount of gas 5 pump members, one of which rotates at higher evolved is considerable in many cases. In one 5 speed than the other, means for raising the prestest on pumping a crude petroleum, the volume of sure of liquid just before delivery into the inlet gas evolved in a certain pump of the type deside of the main pressure pumping members in orscribed was 25 per cent of the volumetric capacity der to prevent formation of vapor in the pump, of the pump.

said means comprising a rotary impeller of a The presence of gas in the pump while pumping 10 type adapted to develop pressure by rotational liquids is deleterious. The gas reduces the voluvelocity, the impeller being operatively connected metric capacity and the efliciency of the pump with, and driven by, the main pumping member since the pump is under the necessity of acting as which runs at the higher speed, the impeller being a compressor as well as a pump. A further disof larger diameter than either of the two main advantage is that the gas bubbles as they pass 15 pumping members, andacasing enclosing the imfrom suction to discharge pressure in the pump peller and having an inlet connection for liquid are abruptly compressed and collapsed, thereby to be pumped delivering to the impeller and also causing considerable vibration in the oil column a liquid connection from the impeller to the inlet on the discharge side of the pump. This effect side of the main pumping members; the impeller may give rise to destructive vibration in the 20 and casing therefor in some modifications being pressure piping and is attended by noise and adapted for ready attachment to and detachment rattle in the pump. The gas evolvingefiect defrom the main pressure pump proper and for rescribed is inherent in the operation of rotary placement with a plain head; all as more fully positive displacement pumps and is aggravated hereinafter set forth and as claimed. at high rotational speeds. It may even occur in 25 There has recently been developed an improved the case of reciprocating pumps when these are type of rotary pump having a rotating ring gear operated at a high piston speed. and a pinion engaging the ring gear and having One achieved object of the invention is the proone less tooth than the ring gear; the tooth shape vision of a ring gear and pinion type pump in being such that during rotation of the two gears which gas formation in the pump is prevented. I 30 a plurality of expanding and contracting chamdo this by providing means for imposing a small bers are formed in inter-tooth spaces. The two plus pressure on the liquid entering the pump; gears are mounted for rotation in a casing which a pressure slightly more than sufficient to overhas abutments separating the side of the gear come pressure drop in the pump due to acceleracombination wherein the inter-tooth chambers tion. There is provided in combination with the 35 are constantly expanding (inlet side) from the pump, an impeller, of the type adapted to develop opposite side, in which the chambers are cona pressure by rotational velocity (the so-called stantly contracting (outlet side). These pumps centrifugal or propeller type), which is larger in are highly eiiicient mechanically and volumetridiameter than the ring and which is rotated di- 4 cally. They are of the true/positive displacement rectly by the pinion; that is, the member which type and are able to deliver at pressures of sevruns at higher speed. The diameter of the imeral hundred pounds Wr q inch- The Pumps peller is proportioned so as to be enough larger are ad p d 190 11111 at g Speed; Speeds around than that of the ring gear as to compensate for 1200 The pmlfm for example may be the total pressure drop including that due to aca ggggi gg ifg g ggf g the ring gear celeration and that due to frictional losses beruns at a rather high rate. Liquid entering the Egg the Impeller and the inlet of the main um at a comparatively slow rate is accelerated f inlet side of the pump, to the peripheral In theaccompanymg drawings are shown more or less diagrammatically, two examples of a spe- 50 s ed of the ring gear. The acceleration is neces s arily accompanied by a drop in pressure. In cific embodiment of the invention. In the showpumping non-volatile liquids, this makes no difings,

ference. But in pumping liquid saturated t Fig. 1 is a view in central vertical section of a gas, or liquids almost at their vaporization point, s pu p p ov with an te chan eable the drop in pressure in the inlet is sometimes booster head; 55

Fig. 2 is a sectional view taken along line 2-2 ofFig. 1;

Fig. 3 is an Fig. 1:

Fig. 4 is a view partly in elevation and partly in vertical section of the pump of Fig. 1 with the booster head replaced by a plain head;

Fig. 5 is a view in vertical section of one end of a pump provided with a modified booster combination; and 1 Fig. 6 is a view of the booster impeller of the pump of Fig. 5.

Referring to the figures, in which like reference characters indicate like parts, the pump is shown as comprising a'main casing ill of general horizontal cylindrical form having a substantially cylindrical cavity 9 therein, a vertically extending outlet i I with fluid conduit l2 therein and a flange l3 for attachment to pipe etc. Casing l0 has an inlet H with a similar flange i5, disposed end elevation corresponding to approximately at right angles to the outlet. The

casing rests on a rectangular base l8. The pumping members are centrally located in the casing. The ring gear comprises a cylindrical gear member ll provided with teeth l8 and annular collars l9 at each end. Mounting sleeves 20 are prorotary races engaging turned portion 28 and the v flxed races being retained in annular recesses 30 in the casing. The ring gear is thus retained for free rotation in the casing. The spaces between the ring gear teeth are left open to serve as fluid outlets as indicated at 3|, these spaces being in communication with inlet [4 and outlet l2. The casing is provided with a suitable upper abutment 35 and lower abutment 36, engaging the periphery of the ring gear and separating the inlet from the outlet side of the pump.

A pinion 32 is provided engaging the teeth of the ring gear and having one less tooth than the ring gear; The pinion is keyed to a drive shaft 33 by a key indicated at 34. The axis of the drive shaft is eccentric with respect to the axis of the ring gear and of the casing. The drive shaft is rotatably. mounted by means of two bearings, shown as roller bearings 48 having sleeves 4| tightly fitted to the drive shaft. At the right end of the pump (Figs. 1 and 4) a head 42 is provided, of roughly conical form and bolted in fluid tight connection to casing ill by means of bolts 43. The head has a bore 44 surrounding shaft 33, containing packing 45 and stufling nut 46 to prevent leakage around the shaft. A locking ring or washer 49 for bearing 40 and lock nut 59 threaded on shaft 33 as at 48 are provided as shown.

At the left hand end of the pump is provided the booster combination. An irregular head 55 having an annular flange 56 is bolted to casing in in fluid tight connection by means of bolts 43. Head 55 has a cylindrical bore 51 concentric with the axis of the pinion and drive shaft and containing second bearing 40 mounted on shaft 33 by sleeve 4i in frictional fltwith the shaft. Thus the pinion and shaft are firmly mounted for rotation at two spaced points. A ring 58 is provided between flange 56 and easing ill, to retain bearings 40 and 21 in place. A thin sleeve 59 spaces left hand sleeve 4| from the pinion.

The end head 55 has attached thereto a housing of irregular shape 68 with a circular flange 8| provided with holes 82, for attachment of pipe etc., a-volute chamber housing portion 83 and a circular flange 84 merged with the volute,

as shown. Housing 60 is attached to head 55 at flange 64, by studs and nuts 54. Housing 88 has a divergent conical inlet 65, coaxial with the pinion and drive shaft and delivering into the volute chamber 66 enclosed by portion 63. Member 55 has a frustoconical projection 61 with a bore 68 closely but freely fitting a threaded extension shaft 69 firmly attached to shaft 33 by a threaded connection as at 10. The outer end of extension 69 has a shank of reduced diameter 15 and a tip 16, threaded as shown. Mounted on shank 15 is an impeller ll, keyed thereto as at 18 and retained by a rounded cap nut 19 threaded on tip 18. The impeller has a plurality of angularly disposed blades 80. The cap 19, the interblade portion of the impeller and projection 6! merge into a smooth and rounded shape as is apparent in Fig. l. The blades of the impeller extend towards chamber 66 leaving a slight clearance 85 adjacent the junction of inlet 65 with chamber 66. The diameter of the impeller is greater than the diameter of the ring gear.

Volute chamber 66 has an outlet 86 with outlet passage 81. Outlet 86 has a flange 88. A double bent conduit 89 having flanges 98 at each end is bolted as at I to outlet 86 and to the flange l5 of the pump inlet. Thus the impeller draws from inlet 65 and delivers through outlet 86, conduit 89 and inlet i4 to the main pump.

In operation, the pump is driven through drive shaft 33 by an electric motor or other power means (not shown) at a fairly high speed. Inlet 65 being in communication with liquid, impeller Tl draws liquid into volutechamber 66 and delivers liquid under slight pressure to the inlet of the pump proper. The rapidly rotating ring gear and pinion combination ll, 32 tends to reduce pressure at the pump inlet; but since the liquid is under suficient positive pressure, there is no net drop. Liquid is delivered through outlet i2.

When gassy liquids are pumped, liquids are kept under pressure from the moment they reach inlet 65 and there is no chance for evolution of gas. The pump runs quietly and smoothly at high eiiiciency.

The diameter of the impeller is made a little l 'arger than that merely necessary to compensate for pressure drop due to acceleration, so as to also compensate for frictional losses in the fluid conduits 81, 89 and I4 and still provide a slight plus pressure in the main pump inlet.

The booster-head shown is readily interchangeablewith an ordinary head in case it is desired to dispense with the booster. Referring to Fig. 4. a simple cap-like head I00 is provided, having a flange lili similar to flange 56 on the booster head and retained to the casing by bolts 43. The head has a bore I51 of the same size as the bore 51 in the booster head,'and bearing 40 is retained therein, a retaining shoulder I02 being provided. Threaded bore I0 is advantageously utilized in this modification, to supplement friction in retaining the shaft in the bearing sleeve 4i. As shown, a retaining bolt 99 is provided, engaging the threads in the shaft end and engaging a retaining ring 9, similar to ring 49 shown at the right hand end of Fig. 1. However, the bolt and ring can often be omitted; frictional contact between the bearing sleeve and the shaft being suflicient.

In replacing the booster head with the plain head, it is merely necessary to take of! the booster head containing its bearing 40 and unscrew extension 69, and then slip on plain head it with its bearing 40. Sometimes, instead of providing the threaded extension 69, it is more convenient to make shaft portion 69 and 33 in one piece, the entire shaft in this case being taken out and replaced with a shorter one when the change is made.

In the embodiment of the invention described, the booster impeller is of. the propeller type. Sometimes it is more convenient to employ a centrifugal type booster impeller. Figs. 5 and 6 illustrate such a modification. The booster casing is made in two pieces: a bearing housing and a centrifugal volute housing III attached thereto. The volute housing has an inlet portion H2 flanged as at 6|, and avolute chamber H3 of the typical shape for centrifugal devices. Shank 69 of unitary shaft I09 is mounted in housing 0 by bearing 40. Extension 15 is provided with a centrifugal impeller, comprising a discoid hub H4 and radial blades H5. retained on the shaft by a nut H6 and a key H8. A spacing disk I" separates the impeller from bearing 40. The out let 81 of volute chamber H is in communication with the inlet of the pump as described in connection with the propeller modification. The

diameter of the centrifugal impeller is considerably greater than that of the ring gear.

In operation, the centrifugal impeller boosts the pressure, to produce the same eifect as described in the case of the propeller modification.

What I claim is:

A pump of the rotary positive displacement type having a chambered casing provided with an inlet and an outlet, a pinion and ring gear serving as pumping members, the pinion rotating at higher speed than the ring gear, means for rotatably mounting the ring gear in the casing, a shaft secured to the pinion, a head at each end of the casing, bearing means in each of said heads for the shaft, an impeller of. a type adapted to develop pressure by rotational velocity in one of the heads, a detachable shaft extension on the end of the shaft extending into said head, the impeller being secured to the shaft extension, an impeller housing surrounding the impeller and having an inlet connection delivering liquid to the impeller and having also a detachable outlet connection from the impeller to the inlet side of the gears, and means for detachably securing the impeller housing and head to the casing, so that the head, bearing therein, housing, impeller and shaft extension can be removed from the casing.

REGINALD J. S. PIGOTT.

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