ZA200405052B - An adjustable leak device for a rotating shaft - Google Patents

Description

An Adjustable Leak Device for a Rotating Shaft

Technical field of the invention

This invention relates to a device and method for controlling a leak of fluid from a reservoir over a rotating shaft, which extends into the reservoir.

Background to the invention

Various seals and sealing methods exist in the art of preventing the leak of fluid from a reservoir past a rotating shaft, which extends into the rese=rvoir. The main methods used in the art are to use paecked seals and mechanical seals. Packed seals rely on a seal formed betwezen the packed mateerial and the shaft and mechanical seals on a seal forrmed between a sealling surface of abrasion resista nt material and a wear face defined by a flansge extending from the shaft. T he packing material of the- packed seal is compressed against the shaft and the resulting friction req uires additional ene rgy to rotate the shaft and causes high wear on the sha ft. The sealing surface of the mechanical seal is spring loaded or urged asgainst the wear surface also causing high wear Of the sealing surfaces. In addition, the mechanical seal and packed seal can also employ pressurtised fluid which flows from the outside of the reseoir past the shaft into tthe reservoir for coomling, lubrication and to prevent Beak of fluid from a reservoir past a rotating shamft. This method of lubrication «an be mechanically comp licated and may cortaminate the fluid inside the re=servoir. Normally, if the lubrication stops, the seal seizes with catastrophic results. Seizing may also o ccur during start up if the sealing surface has bon ded to the wear surface cue to abrasives susspended in the fluid, crystallization, setting or curing o-f substances in susspension or solution. It will be appreciated that, a corrosive - or abrasive tiud ins ide the reservoir will exaggeraate the problems highlightzed with existing se=ils. In a previous application PCT No. PCT/ZA00/0024 2 the applicants desscribed a mechanical seal in vwhich a sealing surface is urged against a we=ar surface, which suffers with true problems discussed above.

General description of the irvention

According to a first asgpect of the invention there is provided a dewvice for controlling a leak of fluid through an opening in a wall over a rotating shaft, which rotating shaft extends ®hrough the opening, the device including a ~first adjustable member adjustabl y mountable to the wall, the member havin g a gene rally stationary working surface spaced from a rotamting working surf. ace which rotates with the shaf®& such that an adjustable leak gap is defitned betwesen the stationary and trae rotating working surfaces to control the lea kof fluid through the opening.

The adjustable member may be coaxially mountable about the siaft, the nmember being axially adjustable and having a generaally stationary working surface spaced from a correesponding rotating working surface of a fla.nge which extends transversely from the shaft such that an adjustable leak gamp is defimed between the stationary working surface and the corresponading rotat ing working surface; and an adjustment mears for axially adjusting tke member, themreby adjusting the adjustable leak gap.

The wall may be any wall, which separates a liquid and a gas med ium.

Typi cally, the wall may be a “wall of a reservoir or a wall of a housing, suc has a pu mp housing, located inside the reservoir.

Typically the shaft and the member may be circular in cross sectiorm.

The adjustment me=ans may be any suitabdle means for .axial displacement of the membe=r. The adjustment means may include a fixxture axially mountable about the member, the member and fixture having complementary threads suckn that rotational movement of the member ca uses axial displacement of the member. The adjustment me=ans may ihen incsiude any mechanical advantage means for rotating the member. In one embodiment, the member rinay be provided with a co-axial annular gearr and the mechanical advantage means being in the form of a worm engagineg the anrsular gear.

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The adj ustment means may include a Bhousing for rotatably housing the worm. The hamusing may be fastened to the fixture. The worm may further be axially slideab le along its axis in the housing and the adjustment meeans may then include an obstruction means for obestructing or inhibiting slideable movement of he worm such that the annular gear can be operative=ly rotated by rotating the= worm. The obstruction meanss may include a locking means to obstruct slide=able movement of the worwm in a first, decrea sed gap, adjustment, direction and slideable movement of the worm in & second, opposite, increased gap, direction. The obst ruction of slideable mo=vement of the worm in the first and second adjustment directions allows the rotation of the member, respectively, to adjustably dec rease the leak gap bettween the working surfaece of the member and the working surface of the flarmge and to adjustably incmrease the gap. insteact, the obstruction means may include an urging meaans which allow slideablee movement of the worm in the second, increased gap —, direction, against the u rging means. The pitch of th € complementary thre=ads of the member and fixture is selected such that, when a rotational fomrce in the second, incre -ased gap, direction is experieraced by the member which cause rotational movement of the member against the urging meamns of the obstruction means, axial movement in thes increased gap direct ion of the member will r-esult. it will oe appreciated that, in the evemt that the working surface of the member and the working surface of the flange adhere together, the rotation of the shaft will apply a rotating force to the member to rotate against the urging means of theme obstruction means of the blocking means to caause axial movement off the member to urge the working surfaces apart to orevent the working surf=aces from seizing together. Once the working surfacess are urged apart, the urcging means of the obstruction rmeans will urge the me=mber back into its adjustted gap position.

In use, the device will be mounted about a rotating shaft, the shaft extending into a reservoir and haaving a flange, which extends transversely therefrom. The device is mounted such that the generally stationary working surface of the adjustable membe-r and the rotating workirg surface of the flange are in close proximity axially opposite each other. Th € member is then axiab ly adjusted until the leak gap allows a desired leak rate of fluid from the rese rvoir.

The device may include a ssecond adjustable member similar to the first adju stable member.

The second adjustable mermber may be coaxially mosuntable about the shaft, the member also being =xially adjustable and having a generally stati onary working surface oppos itely spaced from a corresponding rotating working surface of the flange which extends transversely from the shaft such that a second adjustable leak gap is defined between the wvorking surface of the second member and the comresponding surface of the flange, and an adjustment means for axially adjusting the second member, thereby adjusting the second adjustable leak gap. ~The second member may be coaxially screw" threadedly received inside the firsst member such that the adjustment means- for axially adjusting the second member may be similar to the adjusting: meaans for the first member and such that the working surface of the first— mermber and the working surface =of the second member cooperate to define aa first. outer adjustable leak gap anc a second inner adjustab le leak gap. It willl be appreciated that the second member protects the sheaft against undue= exposure to leaked fluid. it will be appreciated by thmose skilled in the art that forces, other thar axial forces, also known as forcees which cause shaft whip, which act on &a rotating shaft may cause transverse movement of the shaft and its flange. Im ord er to accommodate any trarmsference of non axial movement from the rotating surface of the flange andi the generally stationary wvorking surfaces of the first and/ or second members, and to ensure a constant leak rate, the firs t and! or second members may bee provided with a universal type joint, whic extends between the working surfiface and the annular gear _

A universal type joint shall be understoo-d to be a coupling of tvao parts, the coupling beeing able to accommodate mowement of one or both parts in and out of axial alignment and transmit rotary power from one pamt to the other.

The dewice may further include a seal between the first member and the wall. The seal may include an outer annulaar part with an outward: ly facing sealing surfacez, which sealingly bears against an opposed surface of" the wall or a fixture the=reto, and an inner annular part with an inwardly facing sealing surface, whicha sealingly bears against an Opposed surface of acdjustable member. An «outer diameter of the outer part may be larger than t he outer diameter of th=e inner part and the inner diarmeter of the inner part may be smaller than the inner diameter of the outer par. Then, the inner dizameter of the outer part is smaller than outer diameter of the inner part and ®he parts may abut ann=ularly along opposed surfaces on the parts. The seal further includes an ur-ging means for sealingly urgingg the abutting surfaces together while still allowing movement of the parts alorg the abutting surface=s relative to each other_ The urging means may be one or more screw threeaded or spring loaded studs, which bear against the parts. The outwardly facing surface of the outer part may define an annudar groove for locating an o-ring and the inwardly facing surface of the inner paart may define an annular groove for locating am o-ring. it will be appreciaated that such a seal, which is configured to accommodate shaft whip mov ement, may be used in known mechanical seals, and is therefore a second a spect of the invention.

The fixture may have an annular chanmel defined on the insicle thereof and an outlet: defined therein for collecting &and dispensing any flumid, which leaks from thme reservoir through the openirg defined in the wall over the rotating shaft. It will be appreciated that, in use, the rate of fluid dispensed from the outlezt is proportional to the size of the adjustable leak gap, and the gap can be acljusted accordingly.

The fixcture may also have an inlet defi ned therein for flushing the shaft and the, or each member with a cleaning fluid when desired.

Thea end of the second, inner, meember opposite its worki ng surface may be sealed against the rotating shaft such that the device forms a chamber -for containing collected fluid wintil it has been drained from the device.

The chamber also facilitates flushirg of the device during operation.

According to a further aspect of the invention, there is provided a method for managing a leak of fluid fro m a reservoir past a rotating shaft, which exteends into the reservoir, the method including the step of mounting a device ab<out a rotating shaft, the device defining an adjustable leak gap, as described above.

Detailed «description of the invention

The= invention is now described by way of example with reference to the accomparying drawings. in &he drawings:

Figure 1 shows a sectional side view of a device for controlling a leak of fiuid through zan opening in a wall over a rostating shaft, in accordarmce with the inventiong

Figure 2 sshows a three-dimensional explcoded view of the device;

Figure 3 shows a part sectional front three-dimensional view of the device; and

Figure 4 shows a part sectional rear threee-dimensional view of the device.

Referring now to the drawings, th e device for controling a leak of fluid through zn opening in a wall over a rotating shaft, in accordarce with the invention , is generally indicated by refereznce numeral 10.

The device 10 can, for example, be used to control a leai=< of water (indicated i n Figure 1 by the arrows marke=d 12) through an openirag 13 in a wall 14 of aa water containing reservoir 16 ower a rotating pump shaft 18, which rotating shaft 18 rotates in the direction of “the arrow 19 and extends through the opening 13 into the reservoir 16. For thee sake of clarity, the shaft 18 is not shown in Figures 2 to 4.

The device 10 includes a first adjustable member 20, which iss coaxially mounted ambout the shaft 18 to the wall 14. The member 20 is axially adjustable and has a generally stationary working surface 22 spaczed from a corresponding rotating working surface 2-4 of a flange 26, which extends transversel y from the shaft 18 such that aan adjustable leak gap is defined between the stationary working surface 22 and the correspondirg rotating working su rface 24 to control the leak of wa ter 12 through the openisg 13.

The device 10 further includes an adjustment means generally indicated bby reference numeral 28 for axially adjusting the member 20, thereby adjusting the adjustable leak gamp and the rate of water leaking through th e opening 13. The adjustment means 28 includes a fixture 30, sealably mounted to the wall 14, by means: of the flange 32, and axially about the membe=r 20. The flange 32 is bolted to the wall 14 by means Of bolts 33. it will be aappreciated that, in other embod iments of the invention, the flange 26, fixture 30 and/ or wall 14 can be integ rally formed. The memboer 20 and fixture 30 has complementary threads 3-4 and 36, respectively, such that rotational movement of the member 20 causes axial displacement of the member 20. The adjustment means 28 further includes a rmechanical advantages means for rotating the member 20 relative to the fixture 30. In this embodime=nt, the member 20 is provided with a co-axial annular g ear 38 and the mechanical advantage means is in th-e form of a worm 40 erwgaging the annular gear 38. The adjustment means 28 also includes a hou sing 42 for rotatably Frousing the worm 40. A shaft 43 extends coaxially through and is fast with t he worm 40. The housing 42 iss fastened to the flange 32 with two bolts 44. The worm 40 is axially slideable along its axis in the housing 42 and the adjustment means 28 includes an obstruction means for ob=structing or inhibiting slideable moveme nt of the worm 40 such th at the annular ge=ar 38 can be operatively rotated by rotating the worm 40. ~The obstruction m eans includes a locking means in the form of a nut 46 screws threadedly receiveed at a first end 48 of the shaft 43 to obstruct slideable move=ment of the worm 40 in a first, decreased gap, adjustment, direction, indicated by arrow 50. The shaft 43 passes slideably through a shaft guide 52. The shhaft guide 52 is kept in position in the housing 42 w ith a locking bolt 54 and numt 56 arrangement. The obstruction means further includes an urging means 258 in the form of = coil spring, which allow slideabl e movement of the worm in a second, incre=ased gap, direction indicated by tthe arrow 60, against the uarging means 58. .A nut 59 is lockable to a second e=nd 61 of the shaft 43. Ttne nut 46 is used t-o pre tension the spring 58, then locked to the second end 61 of the shaft 43 with the locking pin 63 allowing the shaft 43 and the worm «40 to be turned with the nut 59 to adjust the adjustable gap.

The obstruction of s lideable movement of the worm 40 in the first 50 and second 60 adjustment directions allows rotatiorm of the member 20 to, respectively, adjustably decrease the leak gap betwezen the working surface 22 of the member 20 and the rotating working surface 24 of the flange 2 6 and to adjustably increase the gaap.

The pitch of the conmplementary threads of the= member 20 and #ixture 30 is selected such that, when a rotational force in the= second, increasecd gap, direction 60 is experienc €d by the member 20, which cause rot=tional movement of the member against the urging mearms 58 of the obstruction means, axial movement in the increased gap directiomn of the member 220 will result. It will be appreciated that, in the event that tte working surface= 22 of the member 20 and the working surface 24 of the fla nge 26 adhere together, for instance at startup of the pump, the rotation of ®&he shaft 18 will a pply a rotating force to the membeer 20 to rotate against the Lirging means 58 causing axial movement of the mermber 20 thereby urging the working surfaces 222 and 24 apart, preventing the working surfaces from sei=zing together. On ce the working surfaces 22 and 2.4 are urged apart, no, or irsufficient rotationaal force is applied to the member 20 and the urging means 58 wilki urge the member 20 back into its adjusted gap, or working position.

The device 10 includes a second adjustable menmber 62 similar to the first adjustable member 20. The second adjustable member 62 is also coaxially mounted about the shaft 18, the member G82 also being axially adjustable and having a generally stationary working ssurface 64 oppositely spaced from a corresponding rotating working surface 24 of the flange 26, which extends transversely from the shaft 18 such that- a second adjustable leak gap is defined between the working surface 64 of trme second member 62 and the corresponding surface 24 of the flange. The de=vice 10 also includes an adjustment means 28 for axially adjusting the secon d member 62, similar to the adjusting means for the first member 20, thereby adjusting the second adjustable leak gap and like reference numerals are used to indicate like parts. The second member 62 is coaxially screw thre=adedly received inside the first member 20, in a similar way as the first membe r 20 is received inside the fixture 30, such that the adjustment means 28 fomr axially adjusting the second member 62 may be similar to the adjusting rmneans 28 for the first member 20 and such that the working surface 22 of the= first member 20 and 203 the working surface 64 of the second member 62 cooperate to define a first outer adjustable leak gap and a second inner adjustable= leak gap.

Forces, other than axial forces, also known ass forces, which causes shaft whip, which act on a rotating shaft may cause transverse movemen-t 255 and/ or vibrations of the shaft and its flange. In order— to accommodate any transference of non axial movement from the rotating s urface 24 of the flanges 26 and the generally stationary working surfaces 22 aned 84 of the first and/or second members 20 and 62, and to ensure a constant leak rate, the first and / or second members 20 and 62 are provided with a uninversal type joint 68 and 70, respectively, which extends between each working surface 22 and 64 anc its respective annular gear 38 and 66. Each joint 6&8 and 70 includes tweo oppositely facing swivel parts, 72 and 74 for the first, outer, member and 7@® and 78 for the second, inner, member, swivelably mmounted at right angle s relative to each other to and over respective mountings rings 80 and 82. On e swivel part 72 and 76 of each joint 68 and 70, resgoectively, is connecte=d to a respective ring 84 an d 86, each having its respectmve working surface 22 and 64. Two o-rings S88 seal the outer surface of the ring 86 again st the respective inner surf=aces of the parts 76 and 78 ®o minimise the shaftk 18 to exposure to leaked weater.

The device 10 further includes a seal generally indicated by nume=ral 30 between the first member 20 and the fixture 30. which in turn is se=alingly mounted to the wall 114. The seal 90 includes an o uter annular part 92 with an outwardly facing sealing surface 94, which sezalingly bears agairst an opposed surface of the fixture 30, and an inne=r annular part 96 vith an inwardly facing sealimng surface 98, which sealingly bears against an opposed surface of the swiveal part 72 of the adjustable mmember 20. The outwardly facing surface 94 of the outer part 92 defines an annular groove for ledcating an o-ring 100 and thme inwardly facing surface of the inner part 96 defi nes an annular groove for Icocating an o-ring 102. An outear diameter of the outer part 92 is larger than the outer diameter of the inner paart 96 and the inner dis ameter of the inner part 96 is smaller than the inner diameter of the outer Dart 92.

Then, the inner diameter of the outer part 92 is srwnaller than outer diarnrmeter of the inner part 96 amnd the parts 92 and 96 abut annularly along o pposed surfaces on the pamts 92 and 96. The seal 908 further includes an urging means in the form of screw threaded studs 104 received in thareaded apertures defined ir the fixture 30 for sealingly wurging the abutting s urfaces together while still a.llowing some movement of ttme parts 92 and 94 aleong the abutting surfaces re lative to each other. A ring 105, of which an outer portion fits inside a groove defined in the inner surface Of the fixture 30 adjacent the outer part keeps the= parts 92 and 96 in position. Bt will be appreciated that the seal 90 is configured to accommodate shaft whip movement =and/ or vibrations.

The fixture 3-0 has an annular channel 1086 and an outlet 108 defined therein for collecting and dispensing any water, which leaks from the reservoir 16 through the opeening 13 defined in the wall 14 over the rotatirg shaft indicated by the arreows 12. It will be appreciated that, in use, the rate of water dispensecd from the outlet 10»8 is proportional to the size2 of the adjustable le. ak gap, and &the gap can be adjusted accordingly.

Thee fixture also hass an inlet 110 defined thmerein for flushing t be channel # 06, each member 20 and 62 and other parfts with a cleaning flLuid when des ired.

Claims (21)

Claims

1. A device for controlling a leak of fluid through arm opening in a wall over a rotating shaft, which rotating shaft extends through the opening, the device i- ncluding: a firsst adjustable member adjustably mountable to the wa'll, the member having a generally stationary working surface spaced from a rostating working surface whaich rotates with the shaft such that an adjustablee leak gap is defined between the stationary and the rotating working surfamces to control the leak of #Fuid through the opening.

2. A device as claimed in claim 1, in which the adjustalole member is coaxially m ountable about the shaft, the member being axially &djustable with its working surface spaced from a corresponding rotating workirng surface of a flange whiczh extends transversely from the shaft, and the device including: an adjustment means for axially adjusting the memmber, thereQy adjusting tie adjustable leak gap.

3. A device as claimed in claim 2, in which the adjustment rmeans includes a fixture axially mountable about the member, the member and fixture having complementary threads such that rotational movement of the nmember causes axial displeacement of the member.

4, A de=vice as claimed in claim 3, in which the adjustment rmeans includes any mechanical advantage means for rotating the member.

5. A d evice as claimed in claim 4, in which the member i=s provided with an annul=ar gear, co-axial with the shaft, and in which t he mechanical advantage= means is in the form of a worm engaging the annular gear.

6. Ad evice as claimed in claim 5, im which the adjustment - means includes a housing for rotatably and axially slicleably housing the worm, the housing being fasteened to the fixture.

7. A device as claimed in claim 6, in which tie adjustment me=ans includes an obstruction mean-s for obstructing or inhibitirg slideable moveement of the worm in the housing such that the annular gear can be operativealy rotated by rotating the worm.

8. A device as claaimed in claim 7, in which tine obstruction means includes a locking means toe prevent slideable moverment of the wormm in a first, decreased gap, adju=stment, direction and slideaable movement o* the worm in a second, opposite, increased gap, direction.

9. A device as cl aimed in claim 7, in which tlhe obstruction means includes a locking means to prevent slideable moverment of the worm in a first, decreased gap, adj ustment, direction and ary urging means, which allow slideable movement: of the worm in the seccomnd, increased g=ap, direction, against the urging meeans.

10. A device as claimed in any one of clamims 2 to 9, which includes a second adjustable member coaxially receive=d inside the fir st adjustable member about the shaft, the second membemr being axially acdjustable and having a generally stationary working surface oppositely sp-aced from a corresponding rotating working surface of the flange winich extends transversely from thre shaft such that a second adjustable leak (jap is defined between the workin: g surface of the second nmember and the corresponding surface of the flange=.

11. A device as claimed in claim 10, in which the secomnd adjustable member is screw thareadedly received in side th e first adjustable member.

12. A device ass claimed in claim 10 or claim 11, which includes an adjustment means or axially adjusting the sec ond member, the=reby adjusting the second adjustatole leak gap.

13. A device as «claimed in any one of claim. s 1 to 12, in whic h the first and/ or second adjustable members is provided with a universal type joint.

Va/0 03/067129 iy PCL_/ZA02/00018

14. A device as claimed in any one of claims 1 to 13, which inclumde a seal between the first a«djustable member and the wall, the seal including an outer annular part with &an outwardly facing sealing s urface, which sealimmgly bears against an oppose=d surface of the wall or a fixture thereto, and an inner annular part axiallwy aligned with the outer annular part and with ar inwardly facing sealing surfeace, which sealingly bears against an opposed surface.

156. A device ass claimed in claim 14, in whiczh the seal includes an urging means for sealingmly urging abutting surfaces «of the annular parts together while still allowing movement of the parts alongs the abutting surface=s relative to each other.

16. A device ass claimed in any one of clainms 3 to 15, in which the fixture 156 has an inner annu®ar channel and an outlet, leaading from the channel, defined therein for collecting and dispensing any fluaid, which leaks th rough the opening in the wal | over the rotating shaft.

17. A device a=s claimed in claim any one of claims 3 to 16, in which the fixture has an inlett defined therein.

18. A seal for =sealing between an outwardly facing annular inrmer surface and an inwardly facing annular outer surfaces, the seal including an outer annular part with an outwardly facing sealing -surface, which sealiingly bears against the inner surface, and an inner annulaar part generally axially aligned with the outer anrwular part and with an inward! -y facing sealing surf-ace, which sealingly bears against the inner surface.

19. A seal as claimed in claim 18, which includes an urging means for sealingly urging abutting surfaces of the anrular parts together while still allowing moveme=nt of the parts along the abutting surfaces relatmve to each other.

20. A dewice for controlling a leak of fluid through an opeaning in a wall ower a rotating shaft, which rotating shaft extends throrugh the openimng, substantially as described herein with reference to ®he accompany ing drawings.

21. A seal substantially as desscibed herein with reference to —the accompanyfing drawings.