Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
~2~8~3
This application is divided from our Canadian application
434,446 filed August 12, 1983. This invention relates to centri-
fugal pumps and to an improved impeller position adjustment fea-
ture in such pumps.
Typically, centrifugally pumps have an impeller which is
axially adjustable but which has no means to determine with pre-
cision the exact position of the impeller.
Summary of the Invention
In one aspect, the invention features a centrifugal pump
having a bladed impeller in a stationary pump housing, the leading
edges of the blades being adjacent a first .radially extending wall
of the housing, a rotatable shaft on w~ich the impeller is mounted,
a shaft support for rotatably holding the end of the shaft which is
opposite the impeller, and adjustable fastening means for connect-
ing the shaft support to a stationary member, the impeller, shaft
and shaft support together being adapted for axial adjustment upon
axial adjustment of the fastening means, the fastening means having
at least two threaded bolts projecting from the stationary member
in a direction parallel to the axis of the shaft, and reference
nuts for fixing the position of the shaft support on the bolts, the
reference nuts having marks at regular angular intervals, and at
least one reference mark on the shaft support adjacent each refer-
ence nut cooperating with the marks on the reference nuts for in-
dicating the axial position of the impeller with respect to the
pump housing.
-- 1 --
In preferred embodiments, the impeller has a radially
extending face opposite the leading edges, the pump housing fur-
ther comprises a second radially extending wall adjacent the face,
and an annular seal is positioned between the face and the second
wall to seal against the second wall when the impeller is withdrawn
from ~he first wall to the second wall; the seal is mounted on the
impeller face; and the two bolts are spaced apart on opposite sides
of the shaft.
The impeller blades can be precisely positioned with
respect to the pump housing to assure maximum pumping efficiency,
the impeller can be repositioned accurately to accommodate blade
wear, and the reEerence nuts can be used to gauge the total blade
wear to determine when the impeller should be replaced. The annu-
lar seal assures that the seal housing is sealed off from the
fluid in the pump housing when the impeller is withdrawn, so that
work can be easily performed in the seal housing.
The following is a description by way of example of cer-
tain 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 of
Figure 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 housing and pump housing.
-- 2 --
~Z~ 8~
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 coils attached to the cover.
Figure 8 is a sectional view similar to Figure 5 showing an
~2~18~80
alternativc scal housing containing a pac~ing scal.
Figure 9 is a vies~ par-tially broken alYay, ta~en along line 9-9
of Figure S.
Structure and Oocration
Referring to Figurc 1 in pump assembly 10 pump housing 11 defines
an impeller cllamber 1~ ~sho~n in Figure 2) in 1~hich impeller 14 rotates to
pump fluid from pump inlet lG to pump outlet lS. Impeller 14 is mounted on
one end of shaft 20, the other end of which is (by means of direct mount
motor adaptor 22) coupled to and aligned ~ith the shaft of motor 24. Behind
pump housing 11, shaft 20 is enclosed by a removable seal housing 26 \~hicll is
bolted to the backplate 2S of pUll)p housing 11. Also bolted to pump housing
11 is one end of a bearing frame adaptor 32 the other end of ~hich is
bolted to bearing housing 34 ~hich serves as a shaft support for the end of
the shaft opposite the impeller) to assure thc a.Yial alignment of shaft '0,
pump housing ll and bearing housi11g 34. Adjustable fastening means 36 arc
positioned behind bearing housing 3-1 for adjusting the a~ial position of
impeller 14. Rear foot 29 and casing foot 31 support the pun1p assembly foot
29 extending on each side of the center of gravity of the assembly ~hen
disconnected from the impeller.
Referring to Figure 2, ~hich sho~is the pump in grcater detail
shaft 20 is supported rotatably by a pair of bearings 42 44 ho-lsed ~ithin
bearing 11ouse 34. The position of rear bcaring 42 is fi.Yed a.Yially ~ith
respect to shaft 20 by recessed shaft surfacc 46 (adjacel1t thc or~ard end
of bearing L12) and by ~asher 4S al1d t1-readed rctaincr nut 50 (adjaccnt the
rear~.~ard cnc1). Bearing 12 is also hcld fi.Yed ~iithil1 a ~carillg cartridge 62
by rctainil1g surfacc 64 al1d by retaining ring G6 l~hicll is boltcd to tl1c bcaring
-- 4 --
ilZ6)8(~i8~
cartridge. Similarly, the position or fron~ bearing !-Z on s~ t _0 is sct
(on the rear end) by recessed shaft surr;lce 5'. ~ sprillO retai~ lg ring 54
(wllicll seats in groove 21 in shaft 20) and retainer 56 to~ether forc^ oil
seal 58 and couyling ring G0 agains~ the front end of bearillg 44, alld ass~lre
proper seal compression of seal 5S.
The shaft assembly, including shaft 20, bearillgs 47, 44, bearing
cartridge 62, and impeller 14 (which is screwed onto the threaded front end
of shaft 20), is free to be moved axially, because the cylindrical outer
surfaee of the cartridge housing 62 is free to slide in the cylindrical
. bearing housing bore 68 in ~hich it is mounted, the eylindrical outer surfaee
of cylindrical bearing 44 is free to slide in the bearing housing bore 70 in
wllich it is mounted, the cylindrieal outer surface of oil seal 55 is free to
slide in eylindrieal bearing frame adaptor bore 72 in wllicll it is mounted,
and shaft 20 is free to slide in the stationary elelnent 74 of seal 7G. The
axial exeursion of the shaft assembly is limited in one direetion by the
radially extending wall 7S of pumy housing 11, wlliell is adjacellt to the
leading edge 80 of impeller 14~ and in the other diroetion by radially
e.~tending faee 82 of bae~plate 2S wllieh is adjaeent to the trailing edge 84 of
impeller 14.
The axial position of the shaft assembly is determined by adjustable
fastening means 36 whieh eomprise two bolts 100 (e.g.,l/2-20 or l/2-13) w11iel
pass throug}l elearanee holes 102 in bearing eartrid~e 6_ alld are firmly
sere~ed into the baek of bearinO housing 34, and a reference nut 104 and a
loe~nut 106 serewed onto eacll bolt lO0, witll the bearill~ cartri-lge betwee
them, so that they can be tightened do~n onto the bearillg c;lrtridge to
adjust and fix its axial position.
iz~
Referring to ~igure .7~ e;lch r^ferellcc n~lt b;ls a rial portion lOS
on ~-~hicll marks 110 are inscribc~ at reg-llar an~ul;lr intcrvals ~c.g. 7~.a)
and are readable in connection ~ith rcfcrcncc !-arl;s 11 on bearill~7
housing 34.
In operation the a.~ial position of the i:~lpcllcr is adjllsted so
that the gap betlieen edse S0 ;Illd ~all 7S ;ill l~ro~tidc ontim-lm l)ulllpillo
efficiency, e.g. a gap oE 0.015 incll. This is acco~ lishcd bv loosenin~
reference nuts 10;~ to~ard the front of the pulnl? assel!lbly alld ti~-htcnillg
locknuts 106 also to~ard the front of the pump asselllbly until the shaft
assembly reaches an axial position at ~hich thc im~cllcr Icaclill~7 edge
strikes the pump housing l~all 7S. The position ol eacll rcferellcc nut
compared ~ith its assoeiated reference mar~ 11' is notcd. rl~c loc~nuts are
backed off and the reference nuts are then turned bacli tol~ards the back of
the pump assembly by a number of marlis 110 ~hicll correspond to the dcsired
impeller gap(as determined by the ang~llar spacillg bet~-een tlle mar!is and
the piteh of the threa~s of bolts 100). ~s the impeller bl;ldes ~e.lr the
shaft assembly can be moved for~ard a precise distallce -to rcposition the
impeller by a similar use of reference nuts 110. I3y recording the total
amount of such adjustments for ~ear it is possible to determine easily ~hen
the impoller should be replaced. The adjustable fastening means 36 also
permits backing off the shaft assellll)ly to the point ~here the rear surface S-~ of
tlle impeller reaches the pulllp housing ~all S'7, and ~hen so backed off an 0-ring
seal 114 in the bacl;l~all of the impeller se~ls off seal housing 26 from fluid
locatocl in the impeller chamber 17~ 50 th~t ~iork can be per~orlned in the seal
housillg ~ithout the presence of the fluid ;Ind ~ithout need of drairling f1uid
from impeller ch;lmber 17 .
-- 6 --
-
~2~
Referring to Figures 2 and ~ a ccntrilug;ll lubricator ~0 (of
metal or plastic) is positio]led in be~ring llousing 34 for lubricating
bearings ~2 44. Lubricator 40 is fi.~ed to shaft 20 by set scre~ 120.
Lubricator 40 llas an annulus 121 ~itll a circular internal tube 122 -the
inner l~all of .~llich is defined by the surface of sh;lft 20. A tubular yassage
through tlle outer ~all of annulus 121 defines en~rance opening 124
tangential to the tube. A number of syaced e.Yit openings 126 (oriented
radially from shaft 20) in its side pass through the outer periphery of
the amlulus. ~lesh screen 12S (e.g., nylon ~itll mesh oyenings bet~een 50
and 300 microns) is arrallged around tlle inner ~all of the tube eovering the
exit openings.
The inner surface of bearing housing 34 is eontoured to define
an oil reservoir 130 containing oil 132 to a level such tllat oil can enter
entranee opening 124 during each rotation of lubricator 40 on sllaft 20.
Oil ~hiell has entered tube 122 is tllro~n eentri:;u~ally out tllrough e.~it
opertings 126 (after passing through sereen 12S, ~hicll removes carbon and par-
ticulate eontaminants). Oil seals 5S and 130 (housed in the oyposite ends
of the bearing housing) and oil seal 131 on the outer surface of bearing
eartridge 62 prevent leakage of oil from the bearing housing.
Referring to Pigures 2 and 5, seal housillg 26 contains a mechanieal
seal 76 (e.g. a seal sold by A. IY. Chesterton Co. Stoneham lassachusetts
under the trade mar}i SS0) having a rotating elemellt 140 (attaclled by set sere
142 to shaIt 20) and a corresponding stationary element 74 Ileld in place by
seal gland lt4 bolted by bolts 146 to tlle seal llousing. Tlle seal housins is
demoullt;lbly connected by bolts 147 to tlle baeliyl.lte 2S. Tlle rotatillS elemellt
alld statiollary elemellt bear agaillst one allotller rotatably at seal su~f.lce l-IS.
-- 7 -
8(~
Seal 76 prevents lea~age to the outside of the pump of any fluid ~hich
(instead of being pumL~ed itltO pump outlet lS! follol~s a fluid patll over and
behind impe].ler 1~, along cavity 150 on tile Dac' of the impeller and into
the seal housing. Iea~age of such fluid from the seal housing is also
prevented by static (e.g., o-ring) seal 152 (bet-~een cover 30 and seal
housing 26), seal 15-1 (betl-een the seal gland and the stationary element of
the seal), seal 156 ~betl~een the seal housing and the backplate of the pump
housing), and seal 15S (bett~een the impeller and the shaft). Cover 30
permits access to seal 76 and shaft 20 l~ithin seal housing 26 for repair,
impeller 1~ being bac~ed to face 82 before cover 30 is opened to seal ch.~mber
1~ from seal housing 26. Seal housillg 26 may also contain a cooling coil
comprising a eoil of tubing 170 (e.g., l/~i" or 3/S" in diameter) centered on
the aYis of the sll.lft and positioned about seal 76 (there being a larger
than usual space of about 1" betl~een the outer surface o shaft 20 and the
inner surface of seal housing 26 ~;hieh can also accommodate electronic
pressure and temperature transducers). The ends of tubing 170 pass througl
and are hel-l by cover 30 alld the ends form entrance and e.Yit openings 172,
17~ igure 6) outside cover 30. Cooling fluid can be pumyed througll the
eooling eoil to eool the seal.
Referring to ~igure 7, alternatively a flusl-ing coil 176
~similar in size and configuration to the cooling coil) ean be attached to
cover 30. The flushing coil has a nwllber of holes 17S througll ~hicll fluslling
fluid (pumped into the flusllillg coil) is spra)ed into the se,ll housing to
flusll it durillg p-l~ ) oper.ltion.
Ilusllillg of the seal housillg can altel~l;ltely l)e accolllL)lislled
throu~lll fl-lsllillg al)l)aratus comL~rising a flusllill(l tul)e lS0 (ligures 5, 6 ;llld 7)
-- 8 --
12~
having all cntrance end 1~2 outside of the scal housing and an e.~it end lS4
e.~tending througll a side wall of thc seal housing and oriented to direct
flushing fluid into the scal housing in a dircction having a componcnt tan-
gential to the interior of the sidc wall of thc housing and in a plane
normal to tlle sllaft a.Yis. Tlle flush tube enters the seal llousing at the
rear cnd of the housing nc.Yt to tlle seal gland which assures that thc entire
seal housing will be thoro-tgllly flushed. The tangential oricntatio1l enables
the fluid to follow the natural cur~ature of t~le inside wall and preventsflushing
fluid from striking the seal directly ~hich reduces vibration and l~ear and
assures efficient seal operation ~llile flushing.
Because of its demountable connection seal housing 26 can be
easily replaced ~ith housings of any other desired configuration. ~or
e.Yample, referring to l~igures S 9 seal housing 26 may be rcplaccd by
demountable packing seal housing 200 (bolted onto backplate 2S) which llas a
stepped interior surface 202 and is closed at its back end by a seal gland
204 which is adjustably bolted on by bolts 206. Gland 20'i has a central
clearance llole 205 (througll ~hich shaft 20 passes) and a radially eYtending
sealing wall 20S facing towards the impeller. A cylindrical rotary member
209 (fiYed on shaft 20) has a corresponding radially e.Ytending sealing wall
210 which has an inner flange 212 close to the shaft and an outer flange 21~
spaced apart from the shaft so that sealing wall 210 and flanges 212 214 form
a recess in wllich rope packing 216 (e.g. ~/S" or 5/16" by 22" long) can be
spirally wrapped. The radial spacillg of the two Llanges is at lcast twice
the packing thickness. Thc a.Yial eYtent of the flallges is less than the
packing thiclilless so tllat as glalld 20l is tightcne(l do~n Usillg bolts 206 tllc
pacliing is comprcssed a.Yi;lllv betwccn thc scaling walls 20S 210. racliing 216
_ g _
lZ~8~
nol~here touches shaft ~0 and so causcs no ~ear o F thc shaft. Packing 216 is
lleld fixed on rotarv member ~09 so t~l~ sealing surface is bet~een t~all 20~
and pac~ing 216 Alternatively the flanges can be part of the seal gland,
the packing can be held fixed in the scaling gland and the sealing surface
can be defined bet~ieen sealing ~all 210 and the packing The space ~ithin
the seal housing is scaled against leakage by static O-ring seals 21~
(bet~een seal gland 20~1 and scal housillg 200), 220 (bet~een the front outer
~all of seal housing 200 and backplate 2~) and 222 (bet~een the rear end
surface of the impeller and the rear radially in~ardly extending surface 226
of rotary member 209). Rotary member 209 extcnds along shaft 20 from seal
gland 20-t to~iard impeller 1~ and is provided at its end adjacent backplate
2S l~ith a helically threaded outl~ardly facing labyrintll seal 230 closely
spaced to e.g. 0.005 inch a~ay from facing inner surface 232 of the seal
housing. The helical labyrinth seal 230 hydrodynamically pumps fluid
outt~ardly from the seal housing upon rotation of the shaft reducing fluid
pressure ~ithin the seal housing.
Referring to Figures 2 3 for locking shaft 20 against rotation
during repair ~ork, removable shaft lock 2~0 ~ShOI~Il ill broken lines) may be
employed l~hich has a central hole ~ihich fits over shat 20 the hole having a
key 2~l2 ~hich mates ~ith a key~ay 2~ provided in shaft 20. The outer
periphery of the shaft lock has a pair of holes 2~16 corresponding to threaded
holes on the back face of the bearing cartridge for bolting on the shaft lock
to prevent rotation of the shaft assembly.
Other embodiments are ~ithill the follo~ing claims.
- 10 -
