US3307486A - Universal joint and sealing means for screw pumps - Google Patents

Universal joint and sealing means for screw pumps Download PDF

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Publication number
US3307486A
US3307486A US478013A US47801365A US3307486A US 3307486 A US3307486 A US 3307486A US 478013 A US478013 A US 478013A US 47801365 A US47801365 A US 47801365A US 3307486 A US3307486 A US 3307486A
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United States
Prior art keywords
rotor
shaft
stator
pin
drive shaft
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Expired - Lifetime
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US478013A
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English (en)
Inventor
Lindberg Gustav Rudolf
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Flygts Pumpar AB
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Flygts Pumpar AB
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C15/00—Component parts, details or accessories of machines, pumps or pumping installations, not provided for in groups F04C2/00 - F04C14/00
    • F04C15/0057—Driving elements, brakes, couplings, transmission specially adapted for machines or pumps
    • F04C15/0076—Fixing rotors on shafts, e.g. by clamping together hub and shaft
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D3/00—Yielding couplings, i.e. with means permitting movement between the connected parts during the drive
    • F16D3/16—Universal joints in which flexibility is produced by means of pivots or sliding or rolling connecting parts

Definitions

  • This invention relates to screw pumps of the type incorporating a single rotor acting in conjunction with a xed stator, and more particularly to a new universal joint and sealing device for such pumps.
  • a known pump of this kind is disclosed in my British Patent No. 972,420, in which pump a rotor having an external single helical thread (i.e., la thread with a single starting point) revolves while simultaneously moving eccentrically in a fixed stator casing having an internal double helical thread (i.e., a thread with two starting points 180 apart), theinternal thread acting in conjuncwith the rotor screw and having a pitch twice that of the rotor thread.
  • the thread of the stator casing is made in some elastic material, e.g., rubber, and between the two pump elements closed voids or pockets are formed, which are moved axially through the pump by continuous moves ment without pulsations.
  • the drive needs to be transmitted by universal joints, and to this end a short intermediate shaft provided with universal joints at its 5 ends is usually arranged between the rotor and the driving shaft.
  • the present invention has the double object of providing in screw pumps of the type in question, on the one hand, a reliable device at the position where the driving shaft enters the pump Casin-g so that the suction side may be arranged at the driving end and, on the other hand, a universal joint couplingwhich is rendered possible by the ice transposition of the suction and pressure sides, the coupling being subjected to compression instead of tension in such an arrangement.
  • this universal joint coupling is formed as two universal joints which are so arranged that the axial force acting on the rotor is completely separated from the forces associated with torque, these two descriptions of forces being borne individually by two distinct elements of each of the universal joints.
  • FIGURE l shows a vertical longitudinal section through a screw pum-p provided with a universal joint and sealing means according to the invention.
  • FIGURE 2 shows the power transmitting intermediate shaft on a larger scale.
  • FIGURE 3 shows a section along the line III-III of FIGURE 2.
  • FIGURE 4 shows, on a larger scale, a portion of FIG- URE l, viz. a central longitudinal section through one rotor end provided with the universal joint.
  • FIGURE 5 is a similar to FIGURE 4 but shows a modiiication of the universal joint.
  • FIGURE 6 is a section along the line VI-VI of FIG- URE 5.
  • FIGURE 7 is a plan View of one of the pin housings (seen from below) which receives the ends of the torque transmitting pin of the modification shown in FIGURE 5, and
  • FIGURE 8 is a section along the line VIII-VIII of FIGURE 7.
  • the pump body of the screw pump shown in FIGURE 4l comprises three sections, viz. an inlet section 10, an outlet section 12,.'and, clamped therebetween, a stator sleeve or stator casing 14, the sections being held together by means of tie bolts (not shown) between the inlet and outlet sections 10 and 12, respectively.
  • a stator of resilient material preferably a comparatively hard grade of synthetic rubber
  • an external flange 16a formed at one end of thestator being secured in sealing relationship between one end of the stator sleeve 14 and the body section 10.
  • the sleeve is sealed at its opposite end by an O-ring 14a.
  • a passage 18 is formed in the flange 16a between the ⁇ end of the stator facing the inlet '10a and the outer peripheral surface of the stator adjacent the flange 16a.
  • This passage l' is for modifying hydraulic grip developed on the outside of the stator and thus provides a kind of automatic hydraulic balancing of the stator, asis further described in our copending application No. 424,0'47, filed January 7, 1965.
  • the inside or inner peripheral surface of-the stator which denes the outer boundary of the pumping chamber proper, is formed as a somewhat rounded screw thread having two starting points.
  • a rotor 2t cooperates therewith, the outside of the rotor being likewise formed ⁇ as a screw thread which, however, has onlyone starting point and a pitch only half that of the stator thread. Furthermore, the tip of the rotor thread is more accentuated .and sharper than the tips of the stator thread.
  • closed pockets or voids are formed which are moved continually axially from the inlet to the outlet during rotation of the rotor while conveying the pumping medium.
  • the necessary eccentric movement of the rotor in the stator brings 4with it the unavoidable complication that drive from the rotor lfrom a stationary but rotatably mounted input shaft must be by means of some kind of universal joint coupling.
  • the rot-or 20 is made hollow, the cavity 22 thus formed being closed towards the outlet side 12a of the pump but open towards the inlet side a which is at the same time the drive side, as may be seen from FIGURE 1.
  • the feature of a hollow rotor not only permits the total length of the pump to be smaller but also the rotor to be cooled from the inside by the pumping medium, a facility which is of great importance in many cases.
  • An intermediate shaft 24 is connected between the rotor and an input drive shaft 26, this intermediate shaft being connected at its ends to the rotor 20 at the output end of the rotor and to the driving shaft 26, respectively, by means of universal joints 30, which are formed in accordance with the invention and to which is transmitted the conical swinging movement of the intermediate shaft caused by the eccentric movement of the rotor.
  • These universal joints which are essential to the invention, will be described in greater detail in the following.
  • the present screw pump is characterized in particular by the feature that its drive side coincides with its suction side and the sealing of the leadin of the driving shaft in the pump body needs to be effective so that air is not sucked along the shaft from the outside into the pump.
  • the shaft lead-in which is most important to the safe and reliable function of the pump, is shown to the right in FIGURE 1.
  • a shaft coupling disc 50 which is rigidly secured by means of a key or spline joint 50a to the outer end of the rather short driving shaft 26 for being drivingly connected to an external prime mover.
  • a double-row angular contact ball bearing 52 Inside of the coupling shaft disc 50 there is a double-row angular contact ball bearing 52 and inside of this there is a sleeve or combined guide and ring seal 54 of metal having the same outer diameter, the said two members being received in an end bore 56 in the pump body section 10.
  • the ring 54 (O-ring 54a) engages in sealing relationship a shoulder 56a at the bottom of the bore 56, and the assembly comprising ball bearing 52 and ring 54 is tightened against the shoulder by means of a clamping disc 53 and bolts 58a.
  • the ring 54 In its outerward facing end, the ring 54 is provided with an enlarged recess 5411 which receives a conventional sealing sleeve 60 for shielding the ball bearing 52.
  • the sleeve or guide and ring seal 54 clears the shaft 26, and between the bottom of the recess 54h and the sleeve 60 there is a space open to the atmosphere ⁇ so that liquid, which may possibly leak out when the pump is at rest, can escape.
  • the outer race of the ball bearing 52 and the guide ring 54 are rigidly secured in the body; the driving shaft 26 is in turn axially fixed in the inner race lof the ball bearing by said race, a spacer ling 62 and the hub 50b of the coupling flange 50 all being tightened against a shoulder 26a on the driving shaft 26 by means of a central bolt 50c with a washer received in the outer end of the shaft, the Washer abutting upon the hub 50b.
  • the driving shaft 26 is axially fixed but is rotatable in the pump body, and it will be readily appreciated that the shaft with the bearing and clamping structure described can, in conjunction with the application of conventional workshop practice, result in a very accurate alignment and centering in the pump body being attained, particularly in relation to the guide and ring seal 54. This is of great importance to faultless functioning of the rotating sealing mechanism used, as will appear hereinafter.
  • a carbon ring 64 On the inside of the guide and ring seal 54 is a carbon ring 64 which is slideably disposed on the shaft 26 against which it forms a seal (for instance, by means of an O-ring 64a) and also rotates with the shaft.
  • the inner end of the driving shaft 26 is provided with a head 26b and between this head and the carbon ring 64 a helical compression spring 66 is interposed which urges the carbon ring into engagement with the guide and ring seal 54.
  • the interengaging surfaces of the two rings are face ground and form together an almost perfect rotor seal.
  • the intermediate shaft 24 is formed at each end with a ball-shaped head 32 having a semispherical surface 28. Perpendicular to the longitudinal'axis, each head is provided with a through-bore 34 whose center axis passes through the center point -of the spherical surface 28. A pin 36, screw threaded at either end, is arranged in each bore 34. Two nuts, which are provided with tapering ends 38a are tightened on the pin 36.
  • spherical seats 42 are formed in the bottom of the rotor and in the driving shaft head, which receive the respective intermediate shaft head T52-with its spherical surface 28.
  • the bores 34 provide a certain amount of play around the pin 36 so that the axial force acting on the rotor is sure to be borne by the ball joint surface proper, not by the pins, which if borne y by the latter would be practically a pure shearing force derived from the torque exerted on the rotor.
  • the bores 34 taper somewhat, partly in the planes common to the respective bore and the intermediate shaft 20 (angle a FIGURE 2) and partly in the planes .of the bores perpendicular to theshaft (angle [3, FIGURE 3).
  • the angles a and are of the order 4 and 1.5, respectively.
  • the intermediate shaft will perform a conical oscillating movement of the total angular displacement 2 arc sin e/ L, which movement causes, on the one hand, ⁇ a small turning -movement on the pins 36 and, on the other, a small lateral deviation allowed by the divergence at each end of the respective bores 34.
  • the conicity is introduced in order that the torque be transmitted by line contact between the pins 36 and the walls of the bore 34, as indicated in FIGURE 3.
  • FIGURES 5-8 a modification of the universal joint is shown whereby wear on the pin is considerably reduced.
  • the pin is free so it is permitted to convert, to an extent quite satisfactory from a practical point of view, its sliding and rubbing movement into a rolling movement, whereby the wear on the pin is reduced into a minimum.
  • the intermediate shaft of the pump is designated by 72 and the pump rotor driven by said shaft is designated by 70.
  • the opposite end (not shown) of the intermediate shaft 72 is connected t-o the driving shaft of the pump by means of a second modied universal joint, this of course being identical with that of FIGURE 5.
  • the torque is transmitted to the rotor by a cross pin 74 passing through the bore 34 in the ball-shaped head 32 and engaging by its ends in a pair of pin housings 76 secured to the rotor, said housings being further described below.
  • the axial forces and the torque are maintained completely separated and by arranging for there to be suitable play on the -pin S4 it is ensured that the pin is not exposed to any stresses caused iby axial forces.
  • each such groove receiving its pin housing 76 snugly.
  • the pin housings are secured in their posit-ons by means of their respective screws 8) which engage -a diametrical screw threaded bore 82, for both screws, in the rotor end beyond the spherical seat 4.2.
  • the screws have preferably cylindrical heads with hexagonal recesses, said head-s being countersunk in the pin housings 76.
  • the pin housings have the form of a parallelepiped and comprise suitable elements of stainless temperable steel which are precision cast to finished size. They are each provided with a stepped through-bore 84 for the screw 80 and are further formed with a rectangular chamber 86, which opens inwardly to receive the end of the pin 74.
  • the pin 74 has a simple straight cylindrical form with square ends and is retained in its place by the bottom of each chamber 86.
  • the through-bore 34 in the ball-shaped end 32 of the intermediate shaft 72 is formed somewhat double-conical so that its walls diverge outwardly from the center.
  • the conicity is a in the plane common to the bore and the intermediate shaft (FIGURE 5), whereasthe conicity is in the plane of the bore perpendicular to the shaft (FIG- URE 6).
  • the angle a is greater than ,8, and the wall of the bore may be provided at 34a (see FIGURE 6) with small flat, or almost flat, wedge-formed surfaces.
  • FIGURE 6 it may be further seen how the pin makes contact with the pin hou-sings and the intermediate shaft, respectively.
  • the conicity is so adjusted in relationship to the diameter of the bore that line contact arises between the -pin and the walls of the bore 34 and, in addition, the play between the pin and the side walls of the pin housings 76 is moderate, so practically speaking, line contact occurs here also.
  • the intermediate shaft 72 When the screw rotor is rotating with concurrent eccentric movement in the stator body the intermediate shaft 72 will execute conical oscillating movement, which means that the shaft and its ball end 32 will oscillate, on the one hand, about the longitudinal axis of the pin 74 and, on the other, about an axis through the center C of the spherical surface and thus of the ball end, said axis being perpendicular to said longitudinal axis and the longitudinal axis of the intermediate shaft.
  • the lastmentioned oscillating axis (through C) is thus perpendicular to the plane of FIGURE 1.
  • the universal joint as a -whole is preferably shielded or sealed by means of an O-ring seal 88 which surrounds the ball end 32 immediately inside of the pin 74, as shown in FIGURE 5. Dirt and foreign matter are thereby prevented from entering between the bearing surfaces.
  • the housings 74 could, for instance, be made in one piece in the form of a caliper-like device which is pushed onto the rotor from the end, the chamber' 86 then being openv at one side for entry of the pins 74.
  • a body having an inlet port and an outlet port
  • sealing means provided around said drive shaft adjacent said inlet port
  • stator having an internal helical thread fixed within said body between said inlet port and said outlet port;
  • a rotor having an external helical thread, said rotor Ibeing mounted for rotation and concurrent eccentric movement within the stator in cooperation with said stator thread;
  • connection comprising universal joint means consisting of a lball-and-socket joint and a cross pin extending diametrically through said ball and socket and secured to said rotor;
  • said intermediate shaft is formed with spherical ends having transverse bores therethrough, said bores receiving pins, the axis of said bores intersecting the axis of said intermediate shaft and the central point of the spherical surface of the ends of shaft, said pin associated with one of said universal joints being secured rigidly to said rotor, said rotor being provided at the point of securement with a spherical- 1y concave seat having its central point on the axis of said pin so that said seat and the corresponding end of said intermediate shaft together form said ball and socket joints, whereas said pin associated with the other universal joint is correspondingly secured to the inner end of said drive shaft and comprises a spherically concave seat on said inner end of said drive shaft, said seat forming with the adjacent spherical end of said intermediate shaft a second ball and socket joint.
  • said torquetransmitting and torque-receiving cross pins comprise straight cylindrical studs each passing with clearance through its respective bore in said ends of said intermediate shaft and said studs having their ends accommodated in diametrically opposed housings provided on the outside of said rotor and secured thereto, said pins being arranged free and iioating in said bores of said intermediate shaft and in said housings, whereby said intermediate shaft oscillating movement caused by the eccentric movement of said rotor causes the pins to undergo a rolling movement while transmitting the torque.
  • said housings comprise metal blocks each snugly accommodated in a longitudinal groove in the end of said rotor and said drive shaft, the edges of said grooves ypreventing said housings from sliding in said direction of the transmitted force.
  • said sealing means comprises a surface-ground carbon ring arranged on said drive shaft and sealingly engaged therewith and rotating in unison with said shaft, said ground end surface of said carbon ring being held by a sprin-g in engagement wit-h a surface ground end of a ring seal which is insertable together with a ball or roller bearing into a bore extending from the outside of the pump lbody, said ring seal being tightened by suitable means against a shoulder at the bottom of said bore, the ends of said ring seal which face said carbon ring and said ball, bearing being parallel so that said drive shaft' is permitted to rotate with its axis exactly at right langles to the sealing plane between said ring seal and said carbon ring.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Rotary Pumps (AREA)
US478013A 1965-01-21 1965-07-16 Universal joint and sealing means for screw pumps Expired - Lifetime US3307486A (en)

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SE817/65A SE314593B (pt) 1965-01-21 1965-01-21

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Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3467018A (en) * 1967-08-21 1969-09-16 Donald R Presson Slurry pump
US3938744A (en) * 1974-09-05 1976-02-17 Allen Clifford H Positive displacement rotary pump and drive coupling therefor
US4907906A (en) * 1987-08-28 1990-03-13 Netzsch-Mohnopumpen Gmbh Pin joint for eccentric worm pumps
US5135059A (en) * 1990-11-19 1992-08-04 Teleco Oilfield Services, Inc. Borehole drilling motor with flexible shaft coupling
US5779460A (en) * 1996-06-07 1998-07-14 Ici Canada Inc. Progressive cavity pump with tamper-proof safety
US6093004A (en) * 1998-02-12 2000-07-25 Zenergy Llc Pump/motor apparatus using 2-lobe stator
US20070253852A1 (en) * 2004-12-15 2007-11-01 Helmuth Weber Compact Eccentric Screw Pump
US20090252630A1 (en) * 2005-08-12 2009-10-08 Heishin Sobi Kabushiki Kaisha Single-Shaft Eccentric Screw Pump
ITTV20100111A1 (it) * 2010-08-03 2012-02-04 Nova Rotors Srl Pompa a cavita' progressiva che integra un gruppo di trasmissione ad elevata affidabilita' e gruppo di trasmissione ad elevata affidabilita'.
US20150010342A1 (en) * 2012-03-27 2015-01-08 Michael Groth Pin Joint For An Eccentric Screw Pump

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19530977C2 (de) * 1995-08-23 1998-04-09 Masch Gmbh Otto Hoelz Wellengelenk einer Exzenterschneckenpumpe

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2212417A (en) * 1938-02-10 1940-08-20 Robbins & Myers Combined motor and pump
US2527673A (en) * 1947-02-28 1950-10-31 Robbins & Myers Internal helical gear pump
US2765114A (en) * 1953-06-15 1956-10-02 Robbins & Myers Cone type compressor

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2212417A (en) * 1938-02-10 1940-08-20 Robbins & Myers Combined motor and pump
US2527673A (en) * 1947-02-28 1950-10-31 Robbins & Myers Internal helical gear pump
US2765114A (en) * 1953-06-15 1956-10-02 Robbins & Myers Cone type compressor

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3467018A (en) * 1967-08-21 1969-09-16 Donald R Presson Slurry pump
US3938744A (en) * 1974-09-05 1976-02-17 Allen Clifford H Positive displacement rotary pump and drive coupling therefor
USRE29626E (en) * 1974-09-05 1978-05-09 Positive displacement rotary pump and drive coupling therefor
US4907906A (en) * 1987-08-28 1990-03-13 Netzsch-Mohnopumpen Gmbh Pin joint for eccentric worm pumps
US5135059A (en) * 1990-11-19 1992-08-04 Teleco Oilfield Services, Inc. Borehole drilling motor with flexible shaft coupling
US5779460A (en) * 1996-06-07 1998-07-14 Ici Canada Inc. Progressive cavity pump with tamper-proof safety
US6093004A (en) * 1998-02-12 2000-07-25 Zenergy Llc Pump/motor apparatus using 2-lobe stator
US20070253852A1 (en) * 2004-12-15 2007-11-01 Helmuth Weber Compact Eccentric Screw Pump
US7465157B2 (en) * 2004-12-15 2008-12-16 Netzsch-Mohnopumpen Gmbh Compact eccentric screw pump
US20090252630A1 (en) * 2005-08-12 2009-10-08 Heishin Sobi Kabushiki Kaisha Single-Shaft Eccentric Screw Pump
ITTV20100111A1 (it) * 2010-08-03 2012-02-04 Nova Rotors Srl Pompa a cavita' progressiva che integra un gruppo di trasmissione ad elevata affidabilita' e gruppo di trasmissione ad elevata affidabilita'.
US20150010342A1 (en) * 2012-03-27 2015-01-08 Michael Groth Pin Joint For An Eccentric Screw Pump

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DE1528937A1 (de) 1969-08-21
SE314593B (pt) 1969-09-08

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