Note: Descriptions are shown in the official language in which they were submitted.
7;33
~N-
This ~nvention re1ates to flu~d handling devices and more par-
ticularly relates to magne~ic drives employin~ drlven posltive dfsplace~ent
pumps ~or handllng fluids~
There are several kno~n pumps oP ~he type ~aYtn~ an electrlc
motor and a ro~ar~y wheel drtven by the mo~r wî~h a coupl~n~ c~nststin~ o~
two gr~ups Q~ permanent magnets to prevent contam~nattQn ~f ~he ~l~id bein~
handled. One group o~ permanen~ magne~s ro~ates ~l~h and ls m~unted ~n the
sha~t o~ ~he motor and the other group o~ magents is m~unted on and r~tates
with the rotor wheel. In these types o~ pumps, the ~nterlQr oP the pump is
sea1ed a~a~nst ths env~ronment b~ means o~ a dlaphragm of nonmagnet~.c m~tertal
disposed betweell ~he ~wo groups of magn~ts. The rotor wheel is generally
connec~d to a pump device.
In U.S. Pa~ent 2,970,548 ~o S. G~ Berner~ 1ssueel Febru~rY 7. l9~1~
a magnet~cally drlven cen~ri~ugal pu~p t5 d~sc1Osed~ The rotor wheel q~ the
pump is coupl~d to an electric motor by two concentr~call~y mounted m~nets"
one on the shaft o~ the motor and the ot~er on the rotcr ~heel ~ ~ther ex~
amples o~ centrl~ugal pumps w~th concentrtcall~y muunted m~ne~ic drives are
shown ln U.S. Patent 39205,~27 to F~ Z~rrmer~n, ~ssued Septe~be~ 14, 1965
and U.S. Patent 3,238,883 Issued to Thomas B~ 17art~n on ~larch 8, 1966. qne
disadvantage o~ concentrically moun~ed magnets ts ~hat the ~iaphr~g~ wall
must be made by welding a p~ece o~ sheet metal back on l~self~ HolYev~r~ tn
~L~ ~'7~3
weldtn~ t~o thln edges of sheet metal7 ~t ts d~ cul~ t~ ~ta~n a s~ati~
factory seam or ~oint~ Purther~ore, lt ts d~ ult to ~abr~cate the
cyllndric~l wall to such an exact size and shape that the wall eyerywhere
w~ll be ~lush agatnst the interface near the s~ator~ In vtew of these
cons~derations, the magnetic gap between c~ncentrlcally m~unted magne~s must
be substantially yreater than c~mparable ax~ally maun~ed ~a~ne~5 Because
of the ~ncrease ln magne~ic gap for concentrlcally moun~ed magnets, there
is an undeslrable increase in the loss o~ magnetic flux through the gap with
a corresponding reduction ln performance and also requires lar~er diameter
components to handle higher torque transfers
In U.S. Patent 2g996~9~4 to G. W~ ~r~ght, issu~d ~ugust 22~ 1961
a submers~ble mo~or driven pump ~or pumping llquid fuel$ utillztng axial
gap nlagnets ~s disclosed. This motor drlven pump utilizes a centrt~ugal
type rotor driven by a sealed motor t~r~ugh a magnettc coupling operating
between an imper~orate wall of the motor houslng. The motor pump is adapted
to ~l~ with1n a variety of ~uel tanks. The dr~v~ng and driven members of
the magnet~c coupling lie on opposite sides of ~he imperforate ~all, ~hich
serves as a rig~d diaphragm betwecn the two magnets. Thus~ ~he dr~ven and
dr~ving me~bers are separated by an axial alr gap. Another example of an
axlal air gap magnetic motor with a centrlfugal pump ls dlsclosed ~n U~S.
Patent 3,223,043 to Harrts Shapiro lssued December 14, 1965.
Centrlfugal pumps have a number o~ def~cienc~es. F~rst, they are
inherently high speed devices and are more eff~clent in ~andling large ~ ows
and low pressure rlses. Centrifugal pumps have lowér efflci@nc~es for small
flows and higher pressure rises. Secondly, the pressure r~se developed by
a centrl~ugal pump is directly proportional to the speed squared~ Thus,
centrifugal pumps do not produce high pressure rises at low speed. Th~rd,
entrifugal pumps have a tendency to caY~tate and loose their prime. ~hen
7332
elther of these conditions occurs~ ~he centrlFu~al pump Wlll n~t pump which
may result in ~enerating heat, noise, vtbrat~on and the premature fal1ure of
the pump.
~ further improvement ln pumps havlns axial air gap magnetic drive
motors ~s shown ln U.S. Patent 3,470,~24 to Elton ~. O'Connor, issued October
7, 1969. O'Connor dlscloses a magnetic drive pump wherein an electrically
powered dr~e motor is sealed from a pump chamber and transmits by electro-
magnet~c ~orces, a rotary dr1ve to a pump impeller in the pump chamber. The
pump has slldlng vanes in a ~ixed caslng so that ~he liquid is directly
dlsplaced withou~ requlr~ng ~he appllca~ion of centrifugal ~orce.
One maJor drawba~k of pos~tive rotary displacement pump~ is that
thelr efficiency is dependent on the machinlng clearances o~ rotatlng members.
The actual clearance~ of course3 Is a function o~ the machining and assembly.
In addition, w~th low viscosity liqulds9 very close tolerances are neces~ary
so as to reduce slippage caused by l~quid leaking through the pump clearances
The amount of sl~p is dependent upon several ~actors. Generally, lncreased
clearances result in greater slip. Thus3 slid~ng vaned pumps do not find
great appl1c~t~on in pumplng low viscoslty liqulds since the sliding vanes
are prone to excessive tip wear wh~ch requires ~heir frequent replacement.
In addition9 such sllding vane pos~tive rotary displacement pumps are complex,
,'~ have high ~et~n~fricti~n losses, are expenslve to make and do not provide
cv~P~ .rs~
a cut off in case o~ ev~r~ss~ o~ the fluid handled.
Therefore, none of the a~oremen~loned centrtfug~l or sltdtny Yane
pumps9 when used with a magnetlc drlve coupllng between the pump and the
electr~c motor, d~scloses a pump suita41e for handllng fuels. In addition,
~.8'i'33~
none of the a~orementioned pumps are simple, inexpensiYe to make and
provides overpressure protection to limit the discharse pressure o~ the
fluid being handled. Finally, none of the aforementioned pumps are
suitable for a mu1titude o~ ~lu~ds, including fuels, provide high pressure ~ ~; at low speed and voltage, have a low ~endency to cav~tate~can be easily
assembled, and further provide high efficiency.
SUMMARY OF THE INVENTION
The present ~nvention is dirçcted to a pump w~th an axial air gap
motor driving a positive displacement gerotor pump which provides positive
lift a~ the inlet. In addition~ the gerotor pump provides hlgh pump effi-
~ b~7~
ciency without hi~h friction and wear as heretofore~exper~enced ln the
prior art designs. The pump is simple and ls adaptable to the necessary
manufacturing clearances a~ low cos~. Furthermore, the present invention
permits the use of increased axial clearances in assembling the pump wtthout
sacriflcing pump efficiency or cost and is suitable for pumping multi-
viscous fluids. Finally, the axial a1r gap gero~or pump prevents contamina-
tton of the ~luid being handled and can easily be adapted to llmit ~he
discharge pressure of the fluid being handled.
The pump has a housing with a chamber having one end ~nd an oppo-
site end. The d1aphragm member is moun~ed ~nside the chamber diYiding the
~nside of the chamber ~nto a ~rst inside port~on adjacent t~ sne end and
a second ins~de portion adjacent the opposi~e end. A f~rst sha~t is rotat-
ably mounted in the first inside portion of the chamber. The sha~t further
has one end adjacent the diaphragm member with the opposlte end hav~ng tha
elec~ric motor moun~ed thereto for rotating the first shaft when energized.
3~
~ cond shaft is rotatably mounted in the second inside portion
of the chamber. The second shaf-t has a first end adjacent the
diaphragrn member and a second end opposite the first end. A mag-
netic driving member is slidably and nonrotatably mounted on the
one end of the firs-t shaft adjacent -to the diaphragm member. A
magnetic driven member is fixedly mounted on the first end of the
s~!cond shaft adjacent to but spaced away from the diaphragm mem-
ber. The magne-tic driven member rotates with the magnetic driv-
iny mernber in response -to a force of magnetic attraction which is
exerted be-tween the magnetic driving and magnetic driven member
through the diaphragm member. Finally, a gerotor pump member,
which is mounted on the opposite end of the second shaft, pumps
fluid when the second shaft is rotated.
It is, therefore, a primary object of this invention
to provide a fluid pump having an axial magnetic coupling with a
nonmagnetic diaphragm member therebetween which is coupled to a
gerotbr pump having an overpressurization limiter at the dis-
charge port. The gerotor pump is designed to safely handle low
viscosity fluids with high pump efficiency. Yurthermore, the
gerotor pump provides positive lift at the inlet, is self-priming,
and has multi-fiuid capabilities. Finally, the losses created
by fluid friction in the pump are minimized to enhance pump
efficiency.
The present invention will be further illustrated by
way of the accompanying drawings, in which:-
Figure 1 is a partial sectional view of a magnetic pump
according to the invention;
Figure 2 is a sectional view along 2-2 of Figure 1 of
the gerotor pump of the invention;
Figure 3 is a sectional view along 3-3 of Figure l;
Figure 4 is a sectional view along 4-4 of Figure l; and
Figure 5 is a perspective view of a gerotor pump
arrangement.
33~:
Referring to the dr~wings, there is shown a positive
displacement, magnetic drive gero-tor pump, generally designa-ted by
the numeral 100, which embodies the invention. The pump 100 is
provided with a housing 10 with one end 12 and an opposite end 18.
The housing 10 has a chamber 20 formed therein. A diaphragm member
50 is secured by suitable means such as welding to the inside
diameter 16 of the housing 10 and divides the chamber 20 into
a first inside portion 22 and an opposite second inside portion
28. The first inside portion 22 is formed adjacent to the one
end 12 of ~he housing 10. The second inside portion is formed
adjacent to the opposite end 18 of the housing 10. A pair of
bearings 32 and 34 are suitably mounted to the inside diameter of
the housing 10 in the first inside portion 22. The one bearing
32 is placed adjacent to the one end 12 and the other bearing 34
is placed adjacent the diaphragm member 50. An electric motor
40, having a drive shaft 48 extending from either side of an
armature 42, is rotatably mounted on the bearings 32,34. Motor
magnets 44 and field windings (not shown) are mounted concen-
trically with the armature 42. The motor magnets 44 and field
windings are mounted to the inside diameter 24 of the first in-
side portion 22 of the chamber 20. The electric motor 40 also
has a commutator 46 mounted adjacen-t the one bearing 32. A
plurality of brushes 52 are conventionally connected
~ t~3~
to electr~cal contacts 54 which project ~hrough the one end 12 and is con-
nected to an electric source (not shown). The brushes 52 are conventionally
mounted onto the commutator 46 so as to provide elec~r;c current to the
co~mutator and ~he armature 42. The field windings are also conventionally
connected to the electrlc contacts (no~ shown) and thence to the electric
source (not shown). The electric source may also be D.C. or alternating
current with the appropriate modifications to the electrical components of
the electric motor. Those skilled in the art will also recognize that the
pump herein described need not be driven by electr7c source means in prac-
ticing the invention and that an hydraulic motor or an air motor may also
be used with appropria~e modifications.
The diaphragm member 50 ~s forme~ of a non-magnetic material for a
purpose to be dascribed herein later. The diaphragm member also constitutes
a fluid seal to prevent fluid leakage between the first lnside portion 22
and the second ins~de portion 28 of the chamber 20.
A first thrust button or washer 56 is mounted be~ween the one end
49 of the dr~ve shaft 48 and the diaphragm member 50. The washer abuts the
d~aphragm member 50 so as to prevent the ona end 49 of the drive shaft 48
from rubbing against the diaphragm member and wearing through the diaphragm
memberc
An annular magnetic driving member 60 is mounted on the one end
49 of the drlve shaft 48 a~jacent to the f1rst thrust washer S6. The magnetic
driving member 60 is axially slidable on the shaft 48 by a plurality of
flats 62 on the inside diameter of the magnetic dr~v1ng member 60 and a
plurality of cooperating flats 47 on the dr~ve shaft 48. Thus~ the magnetic
drivlng member 60 may sllde axially along the shaft 48 towards the dlaphragm
332
member 50 to compensate for production ~olerances and wear of the flrst
thrust washer 56 as required. The magnetic drlving member 60 has an annular
backing member 64 formed of sui~able magnetic permeable material, preferably
of steel. A permanent magnet 66, preferably a ceramic permanent magnet,
is made ln~o elght (8) poles and suitably mounted to the backin~ member
64 50 as to be adjacent the f~rst thrust washer 56 but spaced away from
the d~aphragm member 50. Thus, there ~s an air gap 65 between the d~aphragm
member and the annular magnetic dr~ving member ~0 which varies somewhat as
~ the washer~ wears away.
In the second inner portion 28 of the chamber 20 is mounted a
pair of bearings 36, 38 which are suitably mounted to the houslng 10. A
driven shaft 78 is mounted in the bearings 36~ 38. The firs~ end 82 of the
second or driven shaft 78 is mounted adjacent to the dlaphragm member 50 on
bearing 36 and the second end 84 of the second shaft 78 is mounted on
bearlng 38 adjacent to the oppos~te end 18 of the housing 10.
A second thrust button or washer 58 ls mounted bet~een the first
end 82 of the driven shaft 78 and the diaphragm member 50. The second thrust
button or washer abuts against the diaphragm member 50 so as to prevent the
first end 82 of ~he second sha~t 78 from rubbing through and weartng against
~he diaphragm member 50.
A magnetic driven member 70 is fixedly mounted on the second sha~t
78 for rotatlon therewith. The magnet~c driven member 7d has an annular
backing member 74 formed of suitable magnetical3y permeable material, pre-
ferably o~ steel. A permanent magnet 76, preferably a ceramlc permanent
magnet~ 1s made to have eight (8) poles and suitably mounted to the
backing member 74 so as to be adjacent to th~ washer S8 bu~ spaced away
a predetermined d~stance to ~orm a flxed a~r gap 75 ~rom the dlaphragm
~ 7 3 ~3~
member 50. Those skilled in the art wlll recognize ~hat any equal number
of magnets may be used in the magnets 66, 76 respectively ln order to
provide a magnetic coupl~ng between the magnetic drlven member and the
magnetic dr~ving member. It is important, however, that one of the magnets
66 of the driving member 60 be al~gned w~th the corresponding one of the
magnets 76 on ~he driven member 70. This perm~s the driving member 60
and the driven member 70 to be coupled by the flux path emitted by the
magnetic attractions of one of the magnets 66 through the a~r gap 65,
through the diaphragm member 50, through the air gap 75 and ~hen to one of
the magnets 76. Thus, the magnets 66 are alwqys aligned with the magnets
76 and thus, no slippage occurs between the driving and driven members
when one ~s rotated relative to the other. Sl~ppage between the magnets
66~ 76 respectively occurs if a force overcomes the magnet~c force there-
between such as in the event that the pump is prevented from rotatlon.
On th~ second shaft 78 adiacent the second end 84 is mounted a
gerotor pump 90. The gerotor pump 1s made o~ an annular backplate member
869 an inlet annular m~mber 89 and three (3) cooperat~ny posit~ve displace-
ment members, that is, a male rotor gear 92, an ann~lar female member 94
and an outer annular member 96 as is best shown 1n Flgures 3 and 5.
The annular backplate member 86 ls connected to the 1n$ide d~ameter
sf the second inner portion 28. The backplate member 86 has one face mounted
adjacent to the driven member 70. The oppos~te ~ace has two kidney shaped
- cavities 79, 80 ~ormed one oppos~te the other therein for a purpose to be
i described later on herein. The second shaft ~ passes through the ~nside
diameter of the backplate member. The three a~orement~oned cooperatlny
members 92, 94 and 96 respectively are centrally mounted relat~ve to the
axis of the second shaft ~ so as to abut the annular backplate member 86.
The male ro~or gear 92 is concentr~cally and axially sl~dable and nonrotatably
~3~8~3;~2
mounted to the second shaft. The annular female gear member 94 cooperatively
engages the male rotor gear 92. The outer annular member 96 is mounted
to the ~nside diameter 29 of the second ~nside portion 28 of the chamber 20.
The inside diameter 97 of the outer annular member 96 ls eccentric a pre-
determ~ned radlal distance D from the long^itudlnal axis 99 passing thraugh
the center line o~ ~he outer diameter 98 of the outer annular member 96
for a purpose to be discussed la~er on herein.
The annular female gear member 94 has an ou~er dlameter 95 ~hich
moun~s within the inside diameter 97 ~f the outer annular member 96. The
outer diameter 95 is formed so as to be undersized with the inside d~ameter
97 to provide a slight diametral clearance between the two members. This
diametral clearanceg ~ormed between ~he two members, permits the ~emale tooth
member 94 to float in ~he outer annular member 96. The annular fenale gear
member 94 has an inner annular tooth profile 93. The inner annular tooth
profile is made with one more gear tooth than the teeth 91 on the male
rotor gear 92.
The male rotor gear 92 rotates concentr~cally on the second ~r
drlYen shaft 78. The teeth 91 on the ma1e rotor gear 92 mesh with the inner
annular tooth profile 93 of the female gear member so ~hat both the male
gear 92 an~ the female gear member 94 rotate ln the same direc~lon. The
male gear 92, however, advances one tooth each revolut~on o~ rotation. As
the female gear member ro~ates with the male gear member 92, the teeth mesh
and demesh because of the eccentrlc radial d~stance D o~ the ~nner diameter
97 relatlve to the outer annular member 96.
The gerotor pump 90 ~s mounted between the annular b~ckplate
member 86 and an inlet member 89. The inlet member has tw~ kidney shaped
openings 87, 88 respectively serving as lnlet and outlet open~n~s to the
housing 10. Each of the kidney shaped openings 87, 88 are In ax~al al~n-
ment with each o~ the kidney shaped cavit~es i9~ 80 in the annular backpla~e
~10-
~ 3 3 ~
member 86. The inlet member is slidably moun~ed to th2 inside diam2ter of
the second inner portion of the housing 10. The inlet member is suitably
mounted to the inside diameter of the second inner portion of the housing
10 so that the inlet member is prevented from rotation w~th the gerotor
S pump 90. One o~ the two kidney shaped openings 87 ls pos~tioned ln the top
half portion of ~he inlet member 89 and the second k~dney shaped opening 8B
is positioned in the lower half as is shown in Figure 4. In addltlon, the
annular backplate member 8fi, the outer annular member 96 and tile inlet mem-
ber 89 are connected together by at least ~wo pins 4 as is well known ~n the
art to prevent relative movement therebetween.
As discussed earlierJ the outer annular member 96 has an inslde
diameter 97 which is eccentric a distance D to the hor~zontal dlametral axis
99 passing through the center line o~ the diameter g~ as shown ln Figure 5.
~B3v~
~ The eccentric D is positioned ~ the diametral axis 99 which splits the
upper half of the inlet member~ from the lower hal~ 83 of the inlet member
.
An inlet port 2 is ~ormed in an end plate member 14 moun~ed on the
opposite end 18 of the housing 10 so as ~o connect the inlet k~dney shaped
opening 87 for flow communicatiorl thereto. Similarly, an ou~let port 6 is
formed in ~he end plate member 14 mounted on the opposite end 18 of the
housing 10 so as to connect the outlet to kidney shaped opening 88 for flow
communication thereto. When the gerotor pump 90 is rotated, the meshing
~n~ ~
and demeshing of the teeth causes the fluid to be pumped to be ~w~ into
the volume between the rotor gear 92 and the ~emale member 94. The inlet
port 2 thus provides an inlet fluid passage which is connected by suitable
conduit means to the fluid to be pumped (not shown). The ou~le~ port 6 is
connected by suitable condult means to a receiver (no~ shown) wh~ch receives
the pressurized fluid from the pump 100. A one way fluid ~low device 8, such
~s a conventional check valve, is provided to insure one way
fluid flow from the gerotor pump -through the outlet port 6 and
also to prevent bleed down when the pump 100 is deactivated.
The efficiency of any positive displacemen~ pump such
as herein described depends on the axial clearances of the mem-
bers. In order to insure minimum axial clearance between the
three cooperating gerotor pump members 92, 94 and 96, respectively,
the inlet member ~9 is biased towards the gerotor pump as shown
in Figure 5. For this purpose, a pair of spaced apart cavities
72 are formed in the inlet member 89 adjacent to the opposite end
18 of the housing 10. In each cavity 72 is placed a resilient
member 68, which in the preferred embodiment is a spring biasing
member, such as a helical spring. The resilient member 68 thus
biases the inlet annular member toward the gerotor pump members
92, 94 and 96 and assures minimum axial clearance between the
gerotor pump members 92, 94 and 96, respectively and the inlet
annular member 89 and the backing plate member 86.
When the operation of the pump 100 is desired, the
electric motor 40 is connected to the electric source (not shown).
When the motor rotates, fluid is drawn through the in-
let port 2 which communicates with the inlet kidney shaped open-
ing 87. Fluid is drawn into the female gear member 94 and the
kidney shaped cavity 79 when the male rotor 92 meshes against the
member 94 and, si.multaneously, fluid is expelled from the annular
female gear member 94 and the kidney shaped cavity 80 through the
outlet kidney shaped opening 88 and thence into the outlet port
6. The meshing action, which occurs upon rotation of the male
rotor gear 92 coacting with the inner annular tooth profile 93 of
the female gear member 94, creates
.'~L.~ 7
a series of alternately expand~n~ and c~n~r~ctln~ chAm~ers ther~4P~en~
This actton causes a positive flui~ displqce~ent ~Yhen th~ pw~rp is ln ~lui:~
communicatlon wlth the appropria~e inle~ and ou~le~ por~sO The c~n~uga~ely
generated tooth profiles o~ the male. ~nd ~emale gear members are in contin~
uous fluid contact during operation. Thus, upon one complete revol~tion of
the ~nner member, the male rotor will have advanced one tooth wi~t~ respect
to the ~emale gear member. The volume of ~lu~d displaced ln one revQlutiqn
~s proportlonal to the size of the male rotor, the degree o~ of~set D ~ith
respect to the ~emale member and the thickness o~ the pump~ Thus~ the pump
~ L~ ~
.:, lOQ provides good ~ character~stics since ~luid ls drawn intv ~he unmeshed
space between members 92, ~4 respectively, lmmediatelY upon relative r~tation
of the members 92, ~4. The electrlcal power ~nput through the contacts
leadlng to the motar causes rotation o~ the magnetic dr~vin~ member 60
through the cooperating flats 60, 47 on the drive sha~t 48~ As previously
indicated, the magnetic dr~ving member 60 has a sliding f~.t on the sh.aft 48
so that changes in axial location of the armature o~ the motor will n~t
increase or decrease the rubb~ng pressure o~ the magnetic driving me~ber
60 against the d1aphragm 50. The magnetlc fQrces of the magnetic drivSng
member 60 are transmit~ed through the air gap 65, ~hrough ~he diaphragm
member 50, through ~he air gap 75 and then to the magnet~c dr~Yen member 70
which is ~reely rotatable on the shaft 78. The second thrus~ washer 58
~kprevents ~he dr~ven shaft 78 from rubb~ng agalnst ~he d1aphragm 50. Thus,
Q
the driv~ng member 60 causes the driven member 70 to rotate w~e~er the
driving member is rotated by the motor.
In the event that pressure develops ln the outlet opening 88 o~
the pump to a greater degree than is deslred, the inlet member 89 will move
axlally away ~rcm the gerotor pump members 92, Q4 and 96. The member 89
moves axially away ~rom members 92, 94 and 96 by pressing aga~nst the
-13~ .
-iasing member 68 towards the opposite end 18 of -the pump. As
this occurs, the fluid being pumped is perrnitted to pass from the
outlet ~idney shaped opening 88 to the inlet kidney shaped opening
87 thereby relieving the pressure in the fluid. The degree of
biasing by the biasing member 68 can be varied to match the de-
sired maximum outlet pressure that is to be generated by the pump
100 .
Those skilled in the art will recognize that the pump
described herein can be used to pump low and high viscosity fluids~
Furthermore, the pump will stop pumping in the event that debris
or some other foreign matter is drawn into the pump members 92
and 94 to prevent rotation of the gerotor pump 90.
- 19 -
