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Патент USA US2408316

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Sept 24,1946.
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2,408,315
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SHAFT SEAL
Filed _0st, 4, 1943
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l Patented Sept.24,194e
2,408,315
UNITED STATES PATENT OFFICE
2,408,315
» SHAFT SEAL
Oystein Jacobsen, Montgomery County, Ohio,
as
Dayton,
. signor to The Duriron Company, Inc.,
Ohio, a corporation of New York
' Application october 4 , 1943, Serial No, 504,825
2 Claims. f (Cl. 286-7)
The present invention relates to centrifugal
pumps, and more particularly to the seals of
metrical shape so as to lend itself to ease of as'
sembly within the seal structure as a whole.
Other objects and features will be apparent as
the following specification is perused in con
nection with the accompanying drawing in which:
considerable velocities and adapted to handle cor
CR
Figure l represents a longitudinal fragmen
rosive fluids.
'
When employing theepump for conveying an ` tary section of the improved seal and embody
acid-containing solution, all parts of the pump
ing the principles of the present invention. In
this ñgure the shaftand also the connecting
which come into contact with the corrosive liq
uid are usually fabricated of non-attackalble
bolts and the locating pin are shown in eleva
metal such as silicon iron. Metal of this char
Vtion for .clearness This view is taken along line
acter is so hard that it is practically unmachine
I--l in Figure 42.
.
able. The remaining parts of the pump and
Figure 2 is a vertical sectional view of the struc
ture shown in Figure 1, this view being taken ap
associated structure are usually made of ma
chineable metal such as wrought iron or steel,
proximately along the line 2-2 in Figure l.
i Referring to the drawing, reference character
which -is’readily susceptible to attack by acid so
I designates in general an impeller of the closed
that considerable precaution must be exercised
or shrouded type; >The impeller may comprise,
to prevent the acid from reaching theseparts.
those pumps which are designed to operate at
in part, a plurality of radially extending blades
It has been proposed heretofore to employ -for
~an effective seal `a Vgraphite member which is 20 2 equidistantly disposed about the web 3 of a hub
4. The blades 2 are contained between the oppo
pressed against a rotating part of the shaft at
site walls 5 ofthe shroud and the entire im
a suitable position in order to prevent longitudi
peller assemblage is adapted to rotate within >a
nal and radial creepage of the acid which might
pump casing E of volute configuration. As shown
otherwise reach the bearings in which the shaft
is journaled. Inasmuch as there is relative move 25 in Figure l the inner surface 1 of the casing 6
at one side is given an inwardly tapered or coni
’ ment between. the seal member and the shaft and
other rotating parts 'the seal member becomes
worn over a period of time and often this wear
cal> shape and the adjacent portion of the im
peller shroud or wall is provided with a hori
zontally extending projection B which almost
is not uniform so that even when adequate pres
sure is applied to the seal member a limited but 30 reaches the surface l." This annular projection
is for the purpose of preventing undue leakage
important leakage may take place which might
of the liquid along the inner left hand wall of
impair the operation of the structure as a whole.
the pump casing, particularly when the pump is
It will be understood that in pumps of this char
at rest although it will be understood that a
acter extremely high pressures are often im
small but important amount of leakage mayiind
parted to the liquid and even the smallest irregu
its way throgh the minute space between the
larity at the bearing surface may permit suñi
wall 'l and the projection 8 and whichleakage,
cient leakage to cause considerable damage.
unless Aeventually prevented', might cause creep
It has been custimary in the past, when the
age along the shaft. Such liquid in time would
Contact surface between the seal member and
reach the bearings on which the shaft is mount
40
the rotating part become uneven or irregular, to
ed and attack the metal of these bearings.
disassemble the entire seal structure and to re
The subject rmatter of the present invention is
place the sealing member with a new element by
>concerned primarily with an improved sealing
which the ieloseness of ñt and regularity of sur
structure which prevents that part of the liquid
.face could be obtained. However this discard
l ing .of the used seal member entails consider
able expense which can be avoided by the teach
ings of the present invention.
,
The primary object of the invention is topro
vide a seal structure for centrifugal pumps in
which _might flow past the annular projection
8-from creep-ing along the shaft.
The hub-4 of the impeller is secured by keying
(not shown) to a turned down extension 9 of the
latter is usually mounted
l:mainy shaftY lil. Thejournal
structure which may
on an over-hanging
which the sealing member offersl considerably 50 be constituted of two or more sets of ball bear
longer operating life than similar devices of the
ings »and inwhich the inner ball bearing is posi
prior art.>
tioned notk far from the impeller. A collar Il~
Another cib-ject is to simplify the design and
may be formed integral with the shaft I0 and
construction of the seal member to the extent
positionedA betweenv the shaft portions 9 and Ii)
„that it may-‘be readily vfabricated and is of sym
2,408,315
4
as shown but if desired the collar may be fabri
nermost diameter of the gland plate I9 is slightly
cated separate from the shaft and swetted or
otherwise secured to the shaft at the proper
larger than the seal member 25 so as to constitute
an inwardly extending projection which is re
ceived by the recess Il. The springs are held in
position, preferably under pressure, by means of
position. The shaft portion 9 may terminate in
a relatively large threaded stud I 2 which receives
an impeller nut I3 for forcing the impeller
against the collar I l.
a cover member Y32 which takes generally a cir
cular shape except for a pair of oppositely dis
posed vWin-g portions '33 ,(see Figure 2). These
.
The casing S -at the inner side is provided
with a round opening I4 which just clears the
collar il. The casing is extended longitudinally
to form a tubular portion I5 provided at its left
hand end with a hump shaped enlargement I‘6.
There is an annular recess I l counter-bored from
the outer end of the tubular portion, .this recess
being o_f such depth as to receive a pair of pack- 1
ing rings I8 which may be formed of .synthetic
rubber or other suitable material. It has been
found that substances sold under the vnames of
wing portions are provided With openings for re
ceiving a pair of bolts 34 threaded into the gland
plate I9. The interior diameter of the cover
plate 32 is usually large enough to clear the ad
jacent circumferential surface of the retaining
plate v2l so that no friction at this point is en
countered. Thus by tightening the bolts 34 the
cover plate 32 may be moved to the right and the
compression of the springs 32 is increased. In
asrnueh as the cover plate is effectively secured
to 'the clamp plate 2I through the bolts 34 and
neoprene, Perbunan, and Thiokol are satisfactory
for this purpose. The packing rings are held in 2.0
22 any longitudinal movement of the cover plate
position within the recess il' by a rectangular
with respect jto the shaft II) `Will apply'additional
gland plate It provided Vwith an inwardly ex
pressure against `the springs -3I which in turn
tending hub portion 2i?. The latter has a di
forces the seal ring L25 ïto the right and thereby
ametral size slightly less than that of the re
cess i-'i so that the hub may enter the re-> DU CS increases the Contact pressure between this ring
or member and the shaft collar I I.
cess for a short distance. Thus, the plate is
It is therefore apparent that the pressure on
adapted to apply longitudinal pressure to the
vthe packing rings I 8 may be controlled or ad
rings 'i3 as can be seen in the drawing. Corn
justed by taking up on the bolts 22, thus increas
pressional stress -is exercised at the packing
ing the contact pressure around the outer surface
rings through the plate I9 by means of a split
of the seal member 25 and moreover, tightening
clamp plate 2I to which the gland plate i9 is
' the bolts L24 serves effectively to increase the
bolted at four positions indicated at 22. The
contact pressure between the seal member 25 '
clamping plate 2I is provided with a plurality
and the collar I-I. Consequently, any acid-con
of horizontally disposed lugs 23 which are
taining liquid ywhich iiows »toward the center of
adapted to be bolted together as indicated at 24
the >casing wall >6 and along the interior conical
in Figure 2. This clamp plate has a round open
surface 'í will find -all passageways around the
ing of such shape as to conform to the humped
outer circular surface of the seal member 25 and
surface 'it of the tubular portion I 5 so that when
across the flat >inner `end of the `seal member
the bolts 26 are tightened the parts of the
clamped plate are held together as a single
blocked to fluid creepage so that the shaft IS re
structure about the portion i5. Thus by tight
ening the bolts 22, the gland plate I 9 is caused
mains completely free of the metal-attacking
to move to the right (Figure l) to apply a com
pression effect on vthe packing rings I8. This
compression causes the packing rings to contact
more tightly with the surfaces immediately adja
cent the rings asis well understood in the art.
' fluid.
It will be understood .that in operation the
shaft il) is rotated usually `by an'eleotric motor
(not shown) :and fluid is caused toenter the pump
at the center vof the impeller i. e. about the im
peller nut -ILS .and this fluid is given an outward
centrifugal .movement .by the blades or varies
An annular seal member 25 of graphite sur
and `is collected within a volute chamber (not
rounds 'the shaft I'ii and is contained within the
packing >rings -IS so that the latter bear against .ff shown) which constitutes the pressure outlet.
Thus all of the fluid within the pump is under
the outer surface of the member. This sealing
fairly high pressure and this pressure tends to
element is provided with an annular recess 25
force a >small portion of the fluid into any avail
at each end and is adapted `to bear against the
able space »at therearof the impeller and unless
left -hand surface of the collar II. In order to
assure a fairly close contact between the sealing i perfect .sealing is effected such yfluid might ñnd
its way into the bearings of theshaft. However,
member 25 and the collar II the sealing member
due tothe :presence of the sealing member 25 and
is held longitudinally in its position by means of
the packing rings I8 a completely `tight yseal is
a circular retaining plate 27. This plate has an
inner diameter considerably larger than the size
provided Whic‘hrkeeps Áthe .shaft entirely free of
the liquid ¿regardless of the vamount of pressure
of the shaft il? so as to Áeliminate friction and at
the right hand end is provided with a longitudi GO imparted to the vliquid by the ,impellen While a
nally extending nange portion 28 Which is re
ceived by the left hand annular recess of the seal
member 25. The plate 2l is provided with a cy
lindrical portion 29 of larger diameter and which
portion is adapted to receive a plurality of coun
tersunk openings t@ in which compression springs
3l are inserted. These springs have a normal
length somewhat greater than the depth of the
limited .amount of precession of the .member 25
is permissible, in general Iprefer that this mem
ber shall bev fixed in space. >For this purpose,
there may be provided a locating pin 35 which
is received .by an opening drilled through the
cover plate 32, the retaining plate 2T, vinto the
graphite member'25 as _seen 'in Figure '1.
>,It ’is apparent that there isire‘lative motion be
openings 3G so as to project beyond the outer edge 70 tween .the seal .member 25 and the shaft collar
'I;I and Ynotwithstanding the fact that this mem
of the enlarged portion 29. It is apparent, that
ber is made of graphite, a self-lubricant, a cer
the inner surface of the gland plate I9 must be
tain amount of wear 4at the rotating surface is
provided with a curved portion, indicated at 3Ia,
bound to be present. The Aeffect of rthis wear
which will clear the outside surface of the en
larged portion 29 of the retaining-plate. The in 75 might `not be altogether uniform, for example,
ridges-or grooves might ybe 'formed inthe Vgraph
2,408,315
5
ite sealing member due to some physical pecu
liarity of the collar l l. Inasmuch as these ridges
or other irregularities increase as the pump con
tinues to operate the effectiveness of the seal
man does not have to use care in assembling the
seal member on the shaft as both ends are ex
actlyalike.
Having thus fully described my invention, what
might be impaired. lt has been customary _here
tofore in such a case to dismantle the entire seal
structure by removing the bolts 34 or rather
their nuts and loosening up on the bolts 22 at
which time the seal member 25 may be removed
from its position. A new seal member was
' 6
depth andvdimension and moreover, the work
I claim as new and desire to secure by Letters
Patent, is:
'
l. `A seal for a high pressure fluid pump having
a casing and a pump shaft, a collar on said
shaft, a sealing ring surrounding the shaft and
abutting said collar, said sealing ring being pro
vided with annular recesses at ropposite edges
thereafter provided to replace the old element
after which the bolting operation was performed
thereof immediately adjacent the shaft thereby
in the reverse order.` However, I have found that
it is unnecessary Yto discard the faulty seal mem
ber 25 under such circumstances and in this con
providing a reduced surface area abutting said
collar at a point spaced from said shaft, means
nection, the member is given a symmetrical shape
ring, and simultaneously preventing rotation of
as can be readily seen on the drawing. Thus the
recesses 26 at both ends have the same depth
said ring, said means including a plate loosely
surrounding the shaft and adjustably secured to
said casing“, said plate having an annular pro
jection which extends into the recess of the seal
ing ring at the end remotenîrom the shaft collar
in contact therewith to apply the longitudinal
pressure to said sealing ring and a pin extending
from said plate endwise into said sealing ring.
for applying longitudinal pressure to said sealing
and outer diameters so as to provide end exten
sions of the same length and size. In the case of
wear as explained above it would simply be nec
essary to remove the bolts 34 and loosen the
bolts 22 at which time the ring 25 could be re
moved from the shaft, assuming that the shaft
itself may be readily disconnected from its bear 25
ings as is usually the case.
The member is then
the shaft but in the reverse posi
tion so that the end of the member which had
been located at the left hand side is now posi
’ threaded over
2. A seal for a high pressure fluid pump hav.
ing a casing and a pump shaft, a collar on said
shaft, a sealing ring surrounding theshaft land
abutting said collar, said sealing ring being pro
vided with annular recesses at opposite edges
tioned` in abutting relation with respect to the 30 thereof immediately adjacent the shaft thereby
collar Il. Thus, asy the bolts 22 and 34 are ap
providing a reduced surface area abutting said
plied, complete and tight contact is again estab
collar at a point spaced from said shaft, means
lished between the right hand end of the seal
for applying longitudinal pressure to said sealing
member 25 and the left hand annular surfaceV of
ring, and simultaneously preventing rotation of
35
the collar` Il. The pitted or. other irregularly
said ring, said means including a plate loosely
shaped surface of the seal member is now posi
surrounding the shaft and adjustably secured to
tioned at the left hand end thereof but it will be .
said casing,- said plate havingl an annular pro
noted that no sealing effect is necessary at this
i' jection which extends into the recess of the seal
point since the longitudinal pressure> is exerted 40 ing ring at the end remote from the shaft collar
on the seal member only at the left hand an
in contact therewith to apply the longitudinal
pressure to said sealing ring and a pin extending
nular recess 25.
»
It is therefore apparent that the seal member
from said plate endwise into said sealing ring,
25 is provided initially with two end seal surfaces
said last mentioned plate being divided into two
the second one of which may be used when the 4." parts separated by a pluraltiy of longitudinally
first becomes pitted or otherwise centains irreg
» extending compression springs whereby when the
ularities. To that extent the present invention
position of one of the parts is adjusted with re
contemplates the use of a seal member which
spect to the casing, the springs are placed under
gives at least twice thel wear of such member if
greater compression to force the other part of the
only one sealing surface thereon were available.
plate with greater strength toward the sealing
By providing a symmetrical conñguration vfor the
seal member, the molding and machine work
necessary for fabricating the member is greatly
simplified since the recesses 26 are of the same
ring whereby the pressure between the sealing
ring and the collar is increased.
OYSTEIN JACOBSEN.v
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