Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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This application is divided from our Canadian application
435,446 filed August 12, 1983.
This invention relates to centrifugal pumps and to im-
proved sealing means, and improved seal flushing and cooling means
for such pumps.
In typical centrifugal pumps, a completely closed, one
piece, seal or packing housing is integrally connected to the pump
housing for sealing the drive shaft to which the impeller is con-
nected. This frequently requires draining the system and removing
the impeller for access to the interior of the seal or packing
housing and limits the configuration of the seal or packing housing
to that originally supplied. Flushing ports in seal housings are
often directed in such a manner as to impose unbalanced loads on
the seal.
Summary of the Invention
The ;nvention features a centrifugal pump having a pump
housing, a bladed impeller in the pump housing, a rotatable shaft
extending into the pump housing and on which the impeller is mount-
ed, the pump housing having a radially extending wall adjacent the
impeller and through which the shaft extends, seal means for
sealing the wall through which the shaft extends, and a seal hous-
ing for supporting the seal means and enclosing the portion of the
shaft adjacent the pump housing, the seal housing being demountably
connected to the radially extending wall.
In preferred embodiments, the connection between the seal
housing and the wall is sealed by an annular seal; the seal housing
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has a removable wall portion for permitting access to the seal
means and the portion of the shaft within the seal housing; there
is a tube for carrying cooling fluid, the tube having entrance and
exit ends passing through the removable wall of the seal housing
and a portion of the tube intermediate the tube ends arranged with-
in the seal housing; and the intermediate tube portion is coiled
about the seal means and the shaft.
The seal housing can be easily removed ~or replacement,
maintenance or substitution of different housings; the cover of
the housing can be removed for easy maintenance or replacement of
seals or other parts contained in it and for easy addition of elec-
tronic transducers and cooling and flushing coils.
In another aspect, the invention features flushing
apparatus in the seal housing, having a tube with an entrance end
outside the housing and an exit and extending through a side wall of
the housing and oriented to direct fluid passing through the tube
into the housing in a direction having a component tangential to
the interior of the housing side wall.
In preferred embodiments, the seal is connected to the
housing at one end thereof and the tube passes through the side wall
at a location adjacent that one end, and the direction is in a
plane normal to the axis of the shaft.
The flushing apparatus flushes the entire space within the
seal housing without causing unwanted vibration or inefficient
operation of the seal.
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The following i9 a descr~ption by ~ay of example of
certain embodiments of the present invention reference being had to
the accompanying drawings in which:-
Figure 1 is a side elevation view of the pump assembly.
Figure 2 is an enlarged sectional view of the pump assembly ofFigure 1 with the motor and motor adaptor removed, showing one type
of seal housing.
Figure 3 is a view, taken along line 3-3 of Figure 2.
Figure 4 is a view, taken along line 4-4 of Figure 2.
Figure 5 is a plan view, partly in section and partly broken
away, of the seal hous;ng and pump housing.
Figure 6 is a view, taken along line 6~6 of Figure 5.
Figure 7 (sheet 1 of the Drawings~ is an isometric exploded
view of a seal housing with alternate co;ls attached to the cover.
Figure 8 is a sectional view similar to Figure 5 showing an
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alternative scal housing containing a pLcl;ing ~eal.
Figure 'J is a view partially broken away, taken along line 9-9
of ligure S.
Structure and Operation
Referring to Figurc l in pump assembly lO pump housing 11 defines
an impeller chamber 12 ~showll in Figure 2) in which impeller 14 rotates to
pump fluid from pump inlet 16 to pump outlet lS. Impeller l~ is mounted on
one end of shaft 20 the other end of whicll is (by means of direct mount
motor adaptor 22) coupled to and aligned with the shaft of motor 24. Behind
pump housing 11, shaft 20 is encloscd by a removable seal housing 26 which is
bolted to the backplate 2S of pump housing 11. Also bolted to pump housing
ll is one end of a bearing frame adaptor 32 the other end of which is
bolted to bearing housing 34 ~wllich scrves as a shaft support for the end of
the shaft opposite the impeller~ to assure the axial alignment of shaft 20,
pump housing 11 and bearing housing a4. Adjustable fastening means 36 are
positioned behind bearing housing 34 for adjusting the axial position of
impeller 14. Rear foot 29 and casing foot 31 support the pump assembly foot
29 extending on each side of the center of gravity of the assembly when
disconnectcd from the impeller.
Referring to Fi.gure 2 which sl~ows the pump in greater detail
shaft 20 is supported rotatably by a pair of bearings '12, ~4 housed within
bearing house 34. The position of re.~r bearing ~2 is fixed axially witll
respect to shaft 20 by rccessed shaft surfacc ~6 (adjacent thc forward end
of bearing 42) and by wasllcr ~S alld thrcadcd retaillcr nut 50 ~adj~cent the
rear~ard end). Bearing ~2 is also held fixed witllin a bearillg cartridge 62
by retailliilg surf~cc 6~ and by retailling ring 66 wllicll is bolted to thc bcaring
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~` 31L~C)8~
cartridge. Similarlv, the position of front bearing 44 on shaft 20 is set
(on the rear end) by recessed shaft surfacc 52. A spring retaining ring 5
~ ich seats in groove 21 in shaft 20) ancl retainer 56 together force oil
seal 58 and coupling ring G0 agaillst the front end of bearing 44, and assure
proper seal compression of seal 5S.
The shaft asseMbly, including shaft 20, bearings 42, 44, bearing
cartridge 62, and impeller 1~ hich is scre~ed onto the threaded front encl
of shat 20), is free to be moved a~ially, because the cylindrical outer
surace of the cartridge housing 62 is free to slide in the cylindrical
bearing housing bore 68 in \~hich it is mounted, the cylindrical outer surface
of cylindrical bearing 44 is free to slide in the bearing housing bore 70 in
~hich it is mounted, the cylindrical outer surace of oil seal 58 is free to
slide in cylindrical bearing frame adaptor bore 72 in ~hich it is mounted,
and shaft 20 is free to slide in the stationary element 74 of seal 76. The
axial e~cursion of the shaft assembly is limited in one direction by the
radially extending ~all 78 of pump housillg 11, ~ihicll is adjacent to the
leading edge 80 of impeller 14, and in the other direction by radially
e~tending face 82 of bac~plate 28 ~hich is adjacent to the trailing edge 84 of
impeller 14.
The a~ial position of the shaft assembly is determined by adjustable
fastening means 36 ~hich comprise t~o bolts 100 (e.g.,l/2-20 or 1/2-13) ~hicl
pass through clearance holes 102 in bearing cartriclge G2 ancl are firmly
screl~ecl into the back of bearing ho-lsing 34, and a referellce nut 104 and a
loc~nut lOG scre~ed onto eacll holt 100, ~ith tllc be;lri~ cartridge betl~een
thelll, so that they can be tightened clol~n onto the bearill(1 cartridge to
adjust ancl fi.~ its a,~ial position.
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79
Refcrring to ~igure S~ eacll refercncc nut has a rirn portion lOS
on l-~hicll marks llO are inscribed at regular angul~r intervals ~e.g., 22.5)
and are readable in connection ~Yith rcfcrcncc marks 112 on bearing
housing 34.
In operation, the a.~ial position of the impcllcr is adjusted so
that the gap between edge 80 and ~Ya11 7S :~ill provide optimum p-~lping
efficiency, e.g., a gap of 0.015 inch. This is accompliâllcd bv loosening
reference nuts 10~ toward the front of the pump asscml)ly alld tightcning
locknuts 106 also toward the front of the pump assembly, until the shaft
assembly reaches an axial position at ~hich the impeller leading edge
strikes the pump housing ~all 7S. The position of each refercncc nut
compared l~ith its associated reXcrcnce mar~ 112 is notcd. rhc loclinuts arc
backed off and the reference nuts arc then turned bacli tol~ards the bacli of
the pump assembly by a number of marlis 110 ~hich correspond to the desircd
impeller gap(as determined by the angular spacing bctl-een the marlis and
the pitch of the threads of bolts lO0). ~s the impcllcr blacles l~ear, the
shaft assembly can be movcd for~lard a procise distallcc to reposition the
impeller by a similar use of refcrencc nuts llO. By recording tlle total
amount of such adjustments for ~ear, it is possiblc to determine easily ~hen
the impeller should be re~laccd. The adjustable fastening means 36 also
yermits backing ofE thc shaft asscmbly to tlle point l~llcrc the rear surface Sl of
the impeller reaches tlle pulnp housing l.all S2, and ~hen so backed off an 0-ring
scal 11~1 in tl1e back wall o:E the impeller scals off scal housing ~6 from fluid
located in tl1e lmpeller challlber l~, so th~tt t~orli call bc pcrtormcd in the seal
housing witllout the prcsence of the fluid Ind l~ithout nccd of draillin(1 fluid
from impellcr ch;lmber 12.
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Referring to Fig-Ires 2 and 4 a centrifugal lubricator ~0 (of
metal or plastic) is positionecl in bearing housing 3~ for lubricating
bearings 12 l4. Lubricator 40 is fi~ed to shaft 0 by set scre\~ 120.
Lubricator 40 has an annulus 121 ~ith a circular internal tube 122 the
inner ~all of wlIich is clefined bv the surface of shaft 20. A tubular passage
through the outer I~all of annulus 121 defines entrance opening 124
tangential to the tube. A number of spaced e~it openings 126 (oriented
radially from shaft 20) in its side pass through the outer periphery of
the annulus. ~lesh screen 12S (e.g. nylon ~ith mesh openings bet~-een 50
and ~00 microns) is arranged around the inner I~all of the tube covering the
e.~it openings.
The inner surface of bearing housing 34 is contoured to define
an oil reservoir 130 containing oil 132 to a level such that oil can enter
entrance opening 1~ during each rotation of lubricator ~10 on shaft 20.
Oil ~ihicll has entered tube 122 is thro~n centrifugally out through e~it
openings 126 (after passing througlI screen 12S wlIich removes carbon and par-
ticulate contanlinants). Oil seals 5S and 130 (lIoused in the opposite ends
of the bearing housiI-g) and oil seal 131 on the outer surface of bearing
cartridge 62 prevent leakage of oil from the bearing housing.
Referring to Figures 2 and 5, seal ho-Ising 26 contains a mechanical
seal 76 (e.g., a seal sold by ~ - Chesterton Co- Stollell~m ;~lassachusetts
under the trade mark SSO) havillg a rotatiIlg elelnent 140 (attached by set scre~
1~12 to shaft 20) ancl a correspolldilIg stationary elellleIlt 74 helcl in place by
seal gland 144 bolted by bolts 146 to the seal housilIg. The seal housilIg is
demountably connectecI by bolts 117 to the baclipl;Ite 2S. IIIC rotatilIg elelnent
and stationary element bear against one alIotller rotat.Ibly at seal surf;Ice l~S.
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Seal 7G prevents lea~age to the outsicle of the pump of any fluid ~hich
(ins-teacl of being pumpcd into pUIllp outlet 18) follo~s a fluid path over and
behind impeller 1~ along cavity 150 on the back of the impeller and into
the seal housing. Lea~age o such fluid from the seal housing is also
prevented by static (e.g. 0-ring) seal 152 (bet~een cover 30 and seal
housing 26), seal 15-~ (bet~een the seal gland and the stationary element of
the seal)l seal 15fi (betl~een the seal housing and tlle backplate of the pump
housing) and seal 15S (bet~een the impeller and the shaft). Cover 30
permits access to seal 76 and shaft 20 ~ithin seal housing 26 for repair
impeller 11 being backed to faca S2 before cover 30 is opened to seal chamber
12 from seal housing 26. Seal housillg 26 may also contain a cooling coil
comprising a coil of tubillg 170 (e.g. 1/~" or 3/S" in diLneter) centered on
the axis of the shaft and positioned about seal 76 (there being a larger
than usual space of about 1" betl~een the outer surface of shaft 20 and the
inner surface of seal housing 26 ~-~hicll can also accommodate electronlc
pressure and temperature tra]lsducers). Tlle encls of tubing 170 pass througl
and are held by cover 30 alld tlle ends form entrallce and exit openings 172
174, (~igure 6) outside cover 30. Cooling fluid can be pumpt7d througll the
cooling coil to cool t11e seal.
Referring to ~:igure 7 alternatively a flushing coil 176
(similar in size and configuration to the cooling coil) can be attached to
cover 30. The flushing coil h~s a nulllber of holes 17S througll ~ihicll fluslling
fluid (pumped into the fluslling coil) is sl)ra~ed inte the seal ho-lsing to
flush it during pUIllp operation.
Ilusllillg of thc seal hol1sill~ call altern;ltcly ~e accol1lplisllcd
througll fluslling apparatus comprisillà a flusllillg tul)c lS0 (ligures 5 6 alld 7)
.
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having an entrance end lS2 outside of the scal housing and an exit end lS~l
extellding tllrougll a side ~all of tlle seal llousing and oriented to direct
fluslling fluid into the seal housing in a direction having a component tan-
gential to the interior of the side ~all of the housing and in a plane
normal to tlle shaft axis. The flush tube cnters the seal housing at the
rear end of the housing ne~t to the seal gland ~jhich assures that the entire
seal housing 1~ill be thorougllly flushed. The tangential orientation enables
the fluid to ollol~ the natural curvat-lre of the inside ~all, and preventsflushing
fluid from striking the seal directly l~hich reduces vibration and wear and
assures efficient seal operation ~hile flushing.
Because of its demountable connection seal housing 26 can be
easily replaced \~ith housings of any other desired configuration For
example referring to ~igures 8, 9, seal housing 26 may be replaced by
c'iemount~ble pac~ing seal housing 200 ~bolted onto bac~plate 2S) which has a
stepped interior surface 202 and is closed at its bac',i end by a seal gland
20~ hich is adjustably bolted on by bolts 206. Gland 20~l has a central
clearance hole 205 (through ~hich shaft 20 passes) and a radially extending
sealing ~all 20S facing to~ards the impeller. A cylindrical rotary member
209 (fixed on shaft 20) has ~a corresponding radi~lly extending sealing ~.~all
210 ~hich has an inner flange 212 close to the shaft and an outer flange 21~t
spaced apart from thc shaft so that sealing l~all 210 ancl flanges 212 21-'t form
a recess in ~hicll rope pac~ing 216 (e.g. ,/S" or 5/lG" by 22" long) can be
spirally l.~rapped. Tlle radial spacing of the t~o ^lallges is at loast t~ice
the pacliillg thic~ness. Tlle axial extellt of tlle flallgc?s is less than the
pac',iing thiclilless so th;lt as gland 20l is tigll~ellec', do~n ~ISillg bolts 20G tlle
pac'~ing is cempressed a.~ially bet~eell tlle sealing ~alls 20S 210. rac~ing _16
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~L2~)8~7~
no~here touches sllaft 20 and so causes no wear of the shaft. Packing 216 is
helcl fi~ed on rotary member 209 so the sealing surface is betl~een ~all 20S
and packing 216. Alternatively, the flanges can be part of the seal gland
the packing can be held fi~ed in the sealing gland and the sealing surface
can be defined between sealing wall 210 and the packing. The space within
the seal housing is sealed against leakage by static 0-ring seals 218
(~etween seal gland 20~ and seal housing 200) 220 ~between tlle front outer
wall of seal housing 200 and backplate 2S) and 222 (between the rear end
surface of the impeller and the rear radially inwardly e~tending surface 226
of rotary member 209). Rotary member 209 e~tencls along shaft 20 from seal
gland 20-~ toward impeller 1~ ancl is provicled at its end adjacent backplate
28 with a helically threacled outwardly facing labyrinth seal 230 closely
spaced to, e.g., 0.005 inch away from facing inner surface 232 of the seal
housing. The helical labyrinth seal 230 hydroclynamically pumps fluid
outwardly from the seal housing upon rotation of the shaft, reducing fluid
pressure witllin the seal housing.
Referring to l:igures 2, 3 for locking shaft 20 against rotation
during repair work, removable shaft lock 240 (shown in broken lines) may be
employed wllicll has a central hole wllicll fits over shaft 20 the llole having a
key 2~2 which mates with a keyway 2~ provided in shaft 20. The outer
periphery of the shaft lock has a pair of holes 2~6 correspon~ing to threacled
holes on the back face of the bearing cartriclge for bolting on the shaft lock
to prevent rotation of the shaft assembly.
Other embodimellts are witllill thc followillg claims.
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