US529837A - Screw-pump - Google Patents

Description

(Model.) 2 sheetssheet 1.

W. AE. QUIMBY.

SCREW PUMP.

No. 529,837. Patented Nov.. 27, 1894.

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model.) 2 sheetssneer 2.

W. E. QUIMBY. SCREW PUMP,

Patented Nov. Z7, 1894.

UNITED [STATES PATENT OFFICE.

WILLIAM E. QUIMBY, OF ORANGE, NEW JERSEY.

SCREW-PUMP.

SPECIFICATION forming part of Letters Patent No. 529,837, dated November 27, 1894.

l Application filed August 26., 1892. Serial No. 444.229. (Model.)

To all whom it may concern: p.

Be it known that I, WILLIAM E. QUIMBY, of Orange, New Jersey, have invented certain Improvements in Screw-Pumps, of which the following is a specification.

This invention relates to a screw pump of the type in which there are employed two pairs of screws with intermeshing threads` which are arranged at appropriate distances from each other on two parallel shafts and which rotate within ashell which closely fits the perimeters of the threads. yThe space within the shell between the two pairs of screws is either the induction chamber or the eduction chamber, according to the direction in which the screws are rotated. 0n one side of this chamber the screws have right-hand threads, and on the otherside left-hand threads. Thus when the screws are appropriately turned, the fluid introduced into the central chamber is drawn therefrom in opposite directions and discharged from the ends of the screws into passages communicating with a common outlet. Reversing the direction of rotation of the screws reverses the ydirection of the currents of iuid set in motion by the screws and makes that which was the induction chamber, into which the iiuidwas introduced in the previous case, the eduction chamber, and makes `that which i was previously the outlet, the induction chamber. In either case two equal currents of fluid are established always in .opposite directions either to or from the central chamber. These y two currents counterbalance each other and j hence the screws are not subjected toany endwise thrust -v*in their bearings. It is an incidental advantage of this organization that by so mounting the pump that the axes of the i screws will be horizontal or proximatelyyso, the induction pipe can be introduced to the top of the shell and the pump can be kept full of fluid after it has stopped working and will thus be in readiness lto be immediately started to work again .whenever occasion arises. As heretofore constructed it has been necessary to make the width of the spiral grooves considerably greater than the thickness of the spiral threads, in order to aord clearance for the threads while they intermesh. f This was necessary because any given point on the periphery o f the screw thread" in moving through a given number of degrees describes an arc, the chord of which is longer than the chord of the arc described by a point on the bottom of the groove, or upon a core of the screw in moving through a like number of degrees. It hence follows that to permit even the intermeshing of two parallel screws, having threads o f ordinary shape, the grooves must be wider than the screw threads which they have to contain. The resulting loose fit of the intermeshing threads greatly increases the leakage or backward slip of the fluid, and thus diminishes the effectiveness of the pump in operation.

The presentinvention consists in providing the intermeshing screws with threads, the side walls of which are hollowed out or made approximately concave, while their faces are preferably flat, having the shape of a spiral section of a cylinder. In this device the width of the grooves at the bottom and at their mouths is substantially the same as the width of the faces of the threads, the dierence beas is required to make a sliding Iit between the faces of the threads-'and the bottoms of the grooves respectively. Thus the faces of the intermeshed portions of each' convolution completely close the bottoms of the grooves, in which they are engaged, on a line lying in the plane of the axes of the two screws, while the hollowed out side walls of the threads afford the necessary clearance and a sliding ft for the portions of the faces of the threads immediately adjoining the said line. The faces of the screw-threads have the shape of spiral sections of a cylinder. The side walls ofthe threads are made concave by having formed in them recesseswhich gradually increase in depth from the periphery of the thread lto a point near its base, and then rapidly'diminish in depth from that point to the base. By this device during the intermeshing of the threads the outer corner on one side of the portion of any intermeshed convolution of thread which is, say, beneath the plane. of the axes of the screws and the outer corner on'the other side of the portion of the same convolution which is, say, above the walls of the adjacent convolutions respectively. This greatly diminishes the slip of the ICO said plane are in close proximity to thevside fluid when the pump is at work. The screws have hollow cores and are detachably fastened to their respective shafts.

The invention also embraces means for longitudinally adjusting the screws with relation to each other, and a peculiarly simple and convenient combination of the screws with an electric motor.

The accompanying drawings, illustrating the invention, are as follows:

Figure l is a side elevation. Fig. 2 is an end elevation with the pulley removed. Fig. 3 is an elevation of the end opposite that shown in Fig. 2. Fig. 4 is a longitudinal vertical section of the shell taken through the plane indicated by the dotted line c-fv on Fig. 2. Fig. 5 is a transverse section taken through the plane indicated by the dotted line w--w on Fig. l. Fig. 6 is a horizontal longitudinal section taken through the plane indicated by the dotted line -m on Fig. 2.

Fig. 7 is a transverse vertical section taken through the plane indicated by the dotted line y-g/ on Fig. 6. Fig. S is a top view, partly in section, illustrating the manner of driving the pump by an electric motor. Fig. 9 is an end elevation of parts shown in Fig. 8.

The drawings which represent in detail a screw pump embodying the present improve-4 ments, also include a conventional representation of an electric motor for driving the pump by means of a rotating armature mounted on one of the screw shafts, which for the present purposes may be deemed the driving shaft, and which is geared to the other screw shaft.

The shell, A, of the pump has the shape in cross section of two partly intersecting hollow cylinders with their intersecting portions removed. At the end opposite that at which the power is applied the shell is closed by the head B. rlhe head, B, is provided with a boss, B', in 4which there are two cylindrical apertures for receiving respectively the journal boxes, C and D. These journal boxes are anged cylinders open at theirinner ends and closed at their outer ends, and are secured to the boss, B', by the screws C' C' and D D respectively. They are also centrally perforated at their outer ends to receive the setting bolts C2 and D2 respectively. Each setting bolt is provided with a jam nut, E, for securing it in the position to which it may have been adjusted.

The head, F, is provided with stuffing boxes, F' and F2. The shell, A, is cast integrally with or is affixed to the bed plate G. A standard, G', also integral with or affixed to the bed plate, G, contains the journal boxes, G2 and G2, which respectively afford the outer bearings for the screw shafts. The journal boxes, G2 and G2, are provided with flanges perforated to admit the bolts, G2, by which they are secured toy the standard, G', through which they are inserted.

The driving shaft, a, hasits bearings in the journal boxes, G and G2, and the stufiingbox F'. To vdistinguish it the driving shaft may be regarded as the primary screw shaft. The secondary screw shaft, b, has its bearings in the journal box G2, the stuiiing box F2 inthe head F, and the journal box D in the head B. When the pump is to be driven by abelt, the driving pulley, c, may be alhxed to the end of the journal a. of the driving shaft, 0., projecting outwardly from the standard G'. A hardened steel collar, a2, is pinned to the inner extremity of the journal a'. A washer, a3, of relatively soft metal and a washer, d4, of hardened steel are interposed between the collar, a2, and the inner end of the journal box G2. The secondary shaft, b, provided with a turned down journal, b', is provided with a similar fixed collar, b2, and washers, b2 and b4, the latter bearing against the inner end of the journal box a3. It will be seen that by screwing in the setting bolts, C2 D2, the shafts, a and b, can be forced endwise and their loose washers, a4 and b4, forced against the inner ends of the journal boxes, G2 and G8, respectively. If necessity arises for adjusting the shafts or either of them in the opposite direction, the adjusting screw-bolt can be unscrewed and the journal box at the opposite end may be driven by appropriately turning its fastening bolts G4. Facility is thus aorded for the independent endwise adjustment of the two shafts. Motion is transmitted from the primary screw shaft to the secondary screw shaft by means of the intermeshing pinions, a5 and b5, which are respectively keyed to the shafts a, and b. The portion of the primary shaft, a, within the pump shell, A, is inserted through the hollow cores respectively of the right-hand screw, CZ, and the left-hand screw e, both of which are keyed and pinned to the shaft a..

Similarly, the portion of the secondary screw shaft, b, which is within the pump shell is inserted through the hollow cores, respectively, of the left-hand screw, f, and the righthand screw, g, which are also keyed and pinned to the shaft upon which they are mounted.

As will be seen on reference to Fig. 6, the threads of the right-hand screw, d, intermesh with the threads of the left-hand screw, f, and the threads of the left-hand screw, e, intermesh with the threads of the right-hand screw It will also be seen on reference to Fig. 6, that the screw threads have flat faces corresponding to the shape of the spiral section of a cylinder, and that the width of the bottom and the mouth of the groove is substantially the same as the width of the face of the thread, and that the side walls of the threads are under cut or hollowed out into an approximately concave form. The depth and form in cross section of the recesses in the side walls of the threads will of course vary with threads of different pitches and different diameter. Those shown in the drawings sufliciently illustrate the purpose of theV recessed side walls and the mode of operation of `intermeshing screw threads of the character described.

IOO

IOS

IIO

. side so that their axes lie in the same horizontal plane.

Referring now to the faces of the inter.

meshed portions of the'threads, it will be seen lthat below the horizontal plane one edge, say, for example, the right-hand edge, of each convolution of the thread of, say, the primary screw, is maintain-ed in close proximity to the recessed sides of the adjacent convolutions.

of the thread of the secondary screw. In such case, above the horizontal plane, the left-hand edge of each convolution of the'thread of the secondary screw is maintained in close proximity to the recessed sides of the adjacent convolutions of the threads of the primary screw. It will of course be seen that this mode of constructing the threads by which excessive leakage or backward slip of the fluid, when the pump is in operation, is prevented may be usefully employed not only in a screw pump having two pairs of intermeshing rightand left-hand screws, but also in a screw pump having but one pair of inter-meshing screws. The faces of the threads of the screw, d, loosely fit the concentric wall, h, of the pump shell; those of the screw, e, loosely fit the concentric wall, h, of the pump shell; those of the screw,

3o f, loosely fit the concentric wall, il, of the pump shell, and those of the screw, g, loosely fit the concentric wall, i', of the pump shell.

The space between the opposed ends of the screws, d and c, and f and g, constitutes what for present convenience may be called the induction chamber, H, which is surmounted byy the chest, H', cast integrally with or affixed to the top of the pump shell A. -The chest, H', is open on opposite sides to facilitate the attachment of the suction pipe to either side. When the driving pulley is rotated in the appropriate direction, iiuid, sucked into the chamber, H, is drawn in opposite directions therefrom and discharged into the eduction chambers,I and J, at theopposite ends of the shell, A, and thence makes its way through the channels, I' and J', to the eduction chest, K, to which is connected the discharge pipe L. Reversing the direction of rotation of the driving pulley of course reverses the directions in which the currents of fluid are ydriven through the pump so that the iiuid instead of being drawn in opposite directions outwardly from the central chamber, H, is forced in opposite directions into the chamber H. Hence, as will be perceived, there will be no end thrust of the screw shafts in their bearings whichever way the driving pulley is rotated.

The parts of the pump most subjected to wear are the screws 'and hence they are preferably made with longitudinally hollow cores and are detachably fastened to their respective shafts, so that when worn they may easily be replaced by new ones.

An especially convenient mode of driving the pump is afforded by an electric motor, the plane of rotation of the armature of which is `transverse-to the .axial lines. of the screw spondingly elongated bed plate, as illustrated in Fig. 8, in which vthe field magnets, N, of the motor are shown as arranged between the standards G' and M'. The armature O is mounted upon the extension of the primary screw shaft a. It' a quick running armature is employed, it is loosely ymounted upon the primary shaft, and intermediate speed reducing gearing is used to transmit motion to the primary screw shaft. Such intermediate gearing consists of the pinion O' fastened bythe key O2 to the armature hub O3 afiixed to or formed integrally with a hub P', which is loosely mounted upon the extension of the secondary screw shaft b. A small pinion, P2, affixed to or formed integrally with the loose 'hub P', is adapted to mesh into the gear Q affixed to the primary screw shaft, ct, as shown in Fig. 8.

If a slow running motor is employed, the armature may be keyed to the primary screw shaft, a, as illustrated in Fig. 9; in which case the intermediate gearing will be dis` pensed with, so that the armature may drive the primary screw shaft directly. If intermediate gearing is used, it will of course be proportioned with reference to effecting the required difference of speed between the armature and the primary screw shaft. It will be seen that the intermediate gearing may be thrown out of action by simply remo-fing the key O2 by which the pinion O is fastened to the armature hub O3. Y

For purposes wherein the work to be donc varies from time toltime, as in the case of freight or passenger hydraulic elevators, con- IOOv siderable economic advantages result from the direct application of a shunt-wound electric motor to drive the pump which supplies water to the cylinder of the hydraulic elevator. Such use of a plunger pump is however subject to the objection that the resulting pulsating movements of the water impart unpleasant jerking motions to the elevator.

advantages referred to are fully realized by the employment, under the conditions stated, of the herein described pump which, when driven directly by ash'unt-wound electric motor, delivers a steady stream of Water at practically uniform velocity,while the motor takes more or less current according to the pressure against which the pump has to work, or, in other words, according to the amount of load on the elevator.

What'is claimed as the invention isl. In a screw pump substantially as shown and described, intermeshing right and left hand screws provided with external threads of equal depth, each of which threads is of the same width at its face and at its base and has in its sides recesses which increase gradually IIO This objection is entirely overcome and the .in depth from the perimeter to a point near the base of the thread, and then decrease rap- V idly in depth from said point to said base.

2. In a screw pump substantallyas shown gradually in depth from the perimeter to a; point near the base of the thread, and then decrease rapidly in depth from said point to said base.

3. In a screw pump substantially as shown and described intermeshing right and left hand screws of like radius and pitch and provided with external threads of the same width of face, each of which threads is of the same width at its face and at its base, and has in its sides recesses which increase gradually in depth from the perimeter to a point near the base of the thread, and then decrease rapidly in depth from said point to said base.

4. The combination in a screw pump of two pairs of intermeshing right and left. hand screws provided with external threads, each of which threads is of the same width at its face and at its base, and has in its sides recesses which increase gradually in depth from the perimeter to a point near the base of the thread, and then decrease rapidly in depth from said point to said base, the said screws being mounted on parallel shafts rotating within a shell having interiorly the shape of two intermeshing hollow cylinders with their intersecting portions removed and having a central opening for affording communication with the space within the shell between the opposed ends of the screws, and having openposes set forth.

5. The combination in a screw pump of two pairs of intermeshing right and left hand screws provided with external threads, each of which threads is of the same width at its ings at itsoppositeendsas and 'for the purface and at its base, and has in its sides re cesses which increase gradually in depth from the perimeter to apoint near the base of the thread, and then decrease rapidly in depth from said point to said base, the said screws being mounted on parallel shafts rotating within a shell shaped to fit the perimeters of the unintermeshed portions of `s`aid screws,

an opening in said shell communicating with achamber situated between the opposed ends of said screws and channels connecting the opposite ends of said shell with a common chamber.`

6. The combination inascrew pump of two pairs of intermeshing right and left hand screws provided with hollow cores and with external threads, each of which threads is of the same width at its face and at its base, and has in its sides recesses which increase gradually in depth from the perimeter to a point near the base of the thread, and then decrease rapidly in depth from said point to said base, two parallel shafts upon which said screws are mounted, means for rotating said shafts in opposite directions, a pump shell shaped to t the perimeters of the uninterrneshed portions of the threads of said screws, and means for detaehably fastening said' screws upon said shafts.

WM. E. QUIMBY. Witnesses:

EDw. E. QUIMBY, E. GATTERER.

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