U.S. patent number 3,647,324 [Application Number 04/886,137] was granted by the patent office on 1972-03-07 for electrically driven pumps capable of use as heart pumps.
Invention is credited to Harold D. Kletschka, Edson Howard Rafferty.
United States Patent |
3,647,324 |
Rafferty , et al. |
March 7, 1972 |
ELECTRICALLY DRIVEN PUMPS CAPABLE OF USE AS HEART PUMPS
Abstract
Pumps capable of use as heart pumps; that is, for pumping blood
in connection with the maintenance of the life function in a human
or animal body to replace one or more pumping functions of the
heart. The pumps are also useful for pumping kidney fluids. The
pumps herein described are electrically driven, that is, they are
driven by assemblies which function as electric motors.
Inventors: |
Rafferty; Edson Howard
(Excelsior, MN), Kletschka; Harold D. (Montgomery, AL) |
Family
ID: |
25388455 |
Appl.
No.: |
04/886,137 |
Filed: |
December 18, 1969 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
678265 |
Oct 26, 1967 |
3487784 |
Jan 6, 1970 |
|
|
Current U.S.
Class: |
417/420;
416/186R; 416/179; 415/218.1; 623/3.13; 261/91; 310/63;
310/156.38 |
Current CPC
Class: |
A61M
60/422 (20210101); F05B 2200/15 (20130101); A61M
60/205 (20210101); A61M 60/818 (20210101); A61M
60/82 (20210101); A61M 60/871 (20210101); A61M
60/40 (20210101); A61M 60/148 (20210101) |
Current International
Class: |
A61M
1/10 (20060101); F04b 017/00 (); F04b 035/04 ();
H02k 021/12 () |
Field of
Search: |
;417/420,423,424,406
;415/90 ;310/156 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Walker; Robert M.
Parent Case Text
This application is a continuation-in-part of application Ser. No.
678,265, filed Oct. 26, 1967, by the same inventors and entitled
"Pumps Capable of Use As Heart Pumps," on which application U.S.
Pat. No. 3,487,784 issued on Jan. 6, 1960.
Claims
What is claimed is:
1. Pump for pumping blood, kidney fluids, and other relatively
delicate fluids, comprising pump housing means having a pumping
chamber of substantially circular cross sections therewithin and
having a fluid inlet to the center of said pumping chamber and a
fluid outlet from the periphery of said pumping chamber, rotator
means mounted for rotation within said pumping chamber, electric
motor means comprising magnetic pole means associated with one of
said rotator means and said housing means, winding means associated
with one of said rotator means and said housing means, and means
for supplying electric current to said winding means to drive said
rotator means in rotation whereby said rotator means pumps fluid
through said pumping chamber from said inlet means to said outlet
means; said rotator means comprising vane means extending from said
inlet to adjacent said outlet, said vane means having smooth spaced
facing surfaces defining said flow passage means therebetween which
rotate when said rotator is rotated and frictionally contact fluid
introduced to therebetween through said inlet to cause smooth
circular movement of the fluid concentric with the rotation of said
rotator means and at increased velocity as the fluid moves from
said inlet toward said outlet.
2. The combination of claim 1, said magnetic pole means comprising
magnetized portions of said vane means.
3. The combination of claim 2, said magnetic pole means being
provided in each vane means.
4. The combination of claim 1, said housing means having second
chamber means concentric with said pumping chamber, disc means
disposed in said second chamber means coupled for rotation with
said rotator, seal means around said coupling to prevent fluid flow
from said pumping chamber into said second chamber means, said
magnetic pole means comprising magnetized portions of said disc
means.
5. The combination of claim 1, said magnetic pole means comprising
solenoid winding means carried by said rotator; means for supplying
electrical current to said solenoid winding means.
6. The combination of claim 5, including plastic layer means
covering said solenoid winding means to prevent fluid contact
therewith.
7. The combination of claim 1, said winding means being in said
housing means and being sealed from said pumping chamber by plastic
layer means.
8. The combination of claim 1, said rotator means being coupled to
said electric motor means for rotation thereby by magnetic coupling
means.
9. The combination of claim 8, at least a portion of said rotator
means being suspended for rotation in a magnetic field.
10. Pump for pumping blood, kidney fluids, and other relatively
delicate fluids, comprising pump housing means having a pumping
chamber of substantially circular cross sections therewithin and
having a fluid inlet to the center of said pumping chamber and a
fluid outlet from the periphery of said pumping chamber, rotator
means mounted for rotation within said pumping chamber, electric
motor means comprising magnetic pole means associated with one of
said rotator means and said housing means, and means for supplying
electrical current to said winding means to drive said rotator
means in rotation whereby said rotator means pumps fluid through
said pumping chamber from said inlet means to said outlet means;
said housing means having second chamber means concentric with said
pumping chamber, disc means disposed in said second chamber means
coupled for rotation with said rotator, seal means around said
coupling to prevent fluid flow from said pumping chamber into said
second chamber means, said magnetic pole means comprising
magnetized portions of said disc means.
Description
BACKGROUND OF THE INVENTION
Field of the Invention
The field of the invention is the field relating to apparatus for
pumping blood of a living person, or of a living animal, to replace
one or more pumping functions of the human or animal heart in case
of disability thereof. The heart replacement may be partial or
complete. While the pumps provided according to the invention are
provided principally for pumping blood, it will be apparent that
the pumps may be employed in other instances for pumping other
materials, for instance, for pumping fluids to or from a natural or
artificial kidney. The pumping equipment provided by the invention
has rotating fluid accelerators or rotators. The pumps are adapted
for pumping of blood and other delicate fluid materials without any
pronounced physical effect on the blood or other fluid being
pumped. The pumps do not impose sudden pressure changes, impacts,
rapid changes in direction of flow, in order to prevent injury to
or destruction of the pumped material and its components. Various
electrical drive assemblies are provided according to the invention
for motivating or rotating the rotators employed in the pumps.
DESCRIPTION OF THE PRIOR ART
In the prior art, artificial heart pumps heretofore employed have
been of the positive displacement type. Because of the relatively
delicate nature and structure of blood, and of other body fluids
such as the fluids flow through the kidney, it has been found that
use of centrifugal pumps invariably results in physical disruption
of the blood or other fluid or of at least some of their
components. Although it has been shown that a pulsating movement of
blood through the body is not necessary to sustain life, the prior
art has not afforded a solution to the problems involved in
utilization of centrifugal pumps for pumping blood, since at least
partial destruction of the blood has always resulted when
centrifugal pumps were used. This invention solves these problems,
by providing rotative pumping means for pumping blood, or for
pumping kidney fluids, without any significant destruction of the
blood or other fluid and their components resulting from the
pumping.
SUMMARY OF THE INVENTION
The invention is of rotative pumps which are electrically driven,
i.e., by electric motors, or the like, which are suitable for use
in pumping blood or other fluid for circulation through the body
passages, veins, arteries, etc., of a living person or animal.
The pumps are adaptable for use disposed within a body cavity, for
example as replacements for either or both of the pumping functions
of the heart. The pumps herein provided may also be used for
pumping blood externally of the body. The pumps are adapted to pump
without producing severe pressure changes, physical impacts, and
the like, so that none of the blood components is subjected to
treatment which will destroy it for use. The pumps do not require
the use of valves, such as those of the heart, but valves may be
provided if desired.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a partial view indicating a preferred form of pump having
a built-in drive motor for the accelerator or rotator of the
pump.
FIG. 2 is an axial cross-sectional view of another form of pump
having a built-in drive motor for the accelerator or rotator
assembly of the pump.
FIG. 3 is a vertical cross-sectional view taken at line 3--3 of
FIG. 2.
FIG. 4 is an axial cross-sectional view showing still another form
of pump according to the invention.
FIG. 5 is a partial cross-sectional view taken at line 5--5 of FIG.
4.
FIG. 6 is an axial cross-sectional view showing another form of
pump according to the invention.
FIG. 7 is a perspective view showing a modified form of accelerator
or rotator useful in pumps according to the invention.
FIG. 8 is an elevational view of the apparatus shown in FIG. 7,
taken from the right hand of the apparatus of FIG. 7.
FIG. 9 shows another modified form of accelerator or rotator.
FIGS. 10-15 show six additional forms of accelerators or rotators
useful in the pumps according to the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Blood is a complex and delicate fluid. It is essentially made up of
plasma, a pale yellow liquid containing microscopic materials
including the red corpuscles (erythrocytes), white corpuscles
(leukocytes), and platelets (thrombocytes). These and the other
constituents of blood, as well as the nature of suspension of these
materials in blood, are fairly readily affected by the manner in
which blood is physically handled or treated. Blood subjected to
mechanical shear, to impact, to depressurization, or the like, may
be seriously damaged. The balance between the blood constituents
may be affected. Commencement of deterioration may result from
physical mishandling of blood. Blood which has been damaged may be
unfit for use.
The heart pumps blood through the body in a circulating, cyclic,
fashion. The blood passes repeatedly through the heart. A pump for
replacing one or more pumping functions of the heart should
therefore be capable of repeatedly pumping the same blood, time and
time again, without damaging the blood, at least not more than to
the extent where the body can function to repair or replace the
blood components and eliminate damaged and waste materials
therefrom.
Blood also contains dissolved and chemically combined gases, which
may be seriously affected by improper physical handling of the
blood. It has, for example, been established that subjecting blood
to negative or subatmospheric pressures of, say, minus 300
millimeters of mercury, is detrimental, even when the reduced
pressures are only temporary.
The blood pressure is the pressure of the blood on the walls of the
arteries, and is dependent on the energy of the heart action, the
elasticity of the walls of the arteries, the peripheral resistance
in the capillaries, and the volume and viscosity of the blood. The
maximum pressure occurs at the time of the systole of the left
ventricle of the heart and is termed maximum or systolic pressure.
The normal systolic pressure may be from about 80 millimeters of
mercury (mm. Hg) to about 150 mm. Hg, the pressure ordinarily
increasing with increasing age. Pressures somewhat outside this
range are not uncommon. The minimum pressure is felt at the
diastole of the ventricle and is termed minimum or diastolic
pressure. The diastolic pressure is usually about 30 to 50 mm. Hg
lower than the systolic pressure.
The preferred embodiments of the invention shown and described have
in common that the blood or other delicate fluid is handled gently,
without shear, shock, vibration, impact, severe pressure or
temperature change, or any other condition or treatment which would
unduly damage the blood or other fluid. Essentially nonturbulent
flow is accelerated gradually and smoothly.
The pumping action obtained may be described as radially increasing
pressure gradient pumping, or in some cases more specifically as
forced vortex radially increasing pressure gradient pumping. In
centrifugal pumps, the fluid acted on by the vanes of the impeller
is positively driven or thrown outwardly (radially) by the vane
rotation. The fluid as it moves from the vanes to the ring-shaped
volute space beyond the tips of the vanes is reduced in velocity,
and as the velocity decreases the pressure increases according to
Bernoulli's theorum. On the other hand, in the pumps provided
according to this invention, the pumped fluid is not driven or
thrust outwardly but instead is accelerated to circulate in the
pumping chamber at increasing speeds as it moves farther and
farther from the center. At the outer periphery of the accelerator
or rotator, the speed of the fluid is maximum.
The action of the fluid in the pumps may be clarified by analogy to
a glass of water turning about its vertical axis without sideways
motion or wobble. Because of its contact with the sides and the
inherent potential shear force of the water in the glass, the water
will rotate, in the form of a forced vortex, without much slip or
shear between radially adjacent particles of water, and the water
radially away from the center of rotation will be moving faster
than water nearer the center. If water is introduced through a tube
at the axis of the glass and water is removed through one or more
holes through the side of the glass, water will be pumped by the
rotation of the glass. In the pumps afforded by this invention,
while rotators are provided, in a number of different forms, the
rotators are designed such that they act to increase the swirling
speed of the liquid passing through the pump, but do not act to
drive or throw the liquid toward the periphery or volute of the
pump chamber, but instead only increase the rotational speed of the
liquid. As the rotative speed of the liquid is increased, it
achieves a higher "orbit" about the center of the accelerator and
moves toward the periphery of the chamber.
In each case, the pumps are provided with internal driving means in
the form of an electric motor drive of some form. The electrical
parts of the electrical motor drives are presented in several
different forms as will be later further described.
Referring first to FIG. 1 of the drawings, a pump rotator 20 is
shown which has a plate or disc 21 at each of its sides, which may
be identical or of different forms or sizes, only one being shown
in the drawing, and between which there are provided the equally
circularly spaced curved blades 23a-23h, each curved from its inner
end to its outer end as shown and each having a twist throughout
its length similar to the twist of the propeller. The blades or
vanes may extend beyond the outer edges of the disc 21. Each blade
23a-23h has therearound a winding 24, which is covered by an
impervious layer or membrane 25. The blade windings are connected
to contact elements of a commutator 27. The surrounding pump
housing is provided with the circularly spaced magnets or coils 28,
which are separated from the pumping chamber by an impervious layer
or membrane 29. The commutator rotates with the rotator in the
usual manner of an electric motor. The rotator windings and housing
magnets or coils constitute an internal electric motor for driving
the rotator to pump fluid. The electric motor thus provided may be
of any of the known types, AC or DC, with or without commutation,
powered by electrical conductors leading thereto from any suitable
AC power source or from a battery, located either internally or
externally of the body. The conductors may be disposed through the
outer body wall from the exterior of the body, installed
surgically. The power source may include capacitance connections
across the body wall, with both of its plates beneath the skin, or
with one plate interior of the skin and the other exterior of the
skin. A battery power source may be disposed within the body, and
replaced periodically by surgery, or recharged inductively from the
exterior of the body. Batteries capable of operation for periods in
excess of one year are available so that surgery for their
replacement would need to be done either annually or at longer
intervals.
While the self-contained drive motor is herein shown and described
in connection with the form of rotator shown in FIG. 1, it will be
understood that it may be provided in conjunction with other forms
of rotators disclosed herein or in said U.S. Pat. No. 3,487,784.
Teflon may be used for the membranes 25 and 29 covering the
windings of the electric motor structures.
Accelerator or rotator 20 may be mounted for rotation within any
suitable pumping chamber or housing. The chamber or housing is not
shown in FIG. 1 of the drawings. Fluid entering the pumping chamber
adjacent the shaft 30 on which rotator 20 is mounted is moved
circularly by the vanes of the rotator to move progressively toward
the outer peripheral portion of the pumping chamber. An outlet of
any suitable form is provided for exiting of the fluid from the
periphery of the pumping chamber. The fluid inlets and outlets may
be as described in said U.S. Pat. No. 3,487,784.
Referring now to FIGS. 2 and 3 of the drawings, a plurality of
flared rotator vanes 35, 36, 37 are connected together with plural
rods 38 spaced about the vanes. Vanes 35 and 36 have circular
openings at their smaller ends designated respectively by reference
numerals 39, 40. Vane 37 has a convex rounded center 42 which is
connected to a shaft or rod 43 which is rotatively disposed through
an opening of housing end portion 45. Housing portion 45 is
inwardly curved corresponding to the curvature of vane 37 and the
vane is spaced therefrom as shown. The smaller end of vane 35
outwardly of opening 39 thereof is rotatively sealed within the
housing 48 by a circular seal 49, for example, an O-ring, and a
bearing 50 is provided adjacent the seal. Housing 48 is inwardly
curved corresponding to the curvature of the vane 35.
The three vanes rotate together when driven in rotation as will be
described. The vanes 35-37 are each permanently magnetized to have
alternate magnetic north and south poles "N" and "S" spaced
therearound as indicated in FIG. 3 by reference numerals 51, 52,
respectively, of vane 36. The other two vanes have magnetic poles
therearound in positions corresponding to the pole positions shown
for vane 36. The windings of the electrical motor assembly are
indicated by reference numeral 54, and are disposed within housing
48 around the outside of the outer edges of vanes 35-37. Separate
magnets may be connected to the vanes, instead of the vanes being
magnetized, if desired.
Housing 48, at its left-hand end as shown in FIG. 2, is inwardly
and outwardly curved corresponding to the curvature of vane 35. An
inwardly projecting thickened wall portion 55 surrounds the fluid
inlet to the pump. Portion 45 of the housing is, as has been
described, inwardly curved corresponding to the curvature of vane
37, and is flat at its outer side. The surrounding portion 57 of
the housing wall has winding 54 disposed therein and extends around
the outer edges of the vanes, and is spaced outwardly uniformly
therefrom. The inner surface of wall 57 has a pair of circular
bevelled-sided annular projections 59, 60 which are centered
between the vanes 35, 36 and 36, 37 respectively.
The electrical switching elements for the windings 54 are disposed
inside of housing portion 45 at 62. The rod 43 is journaled through
bearing 63 and serves to rotate the necessary switching elements at
62. The switching elements 62 are connected to the windings in
customary fashion, these connections not being shown in the
drawings because they are of standard conventional form in order
that the winding currents may be alternated as required for the
apparatus to perform its rotative motive function. An electric
power source for the drive motor is provided and is connected to
leads 64, 65, the power source being of any convenient nature. When
electrical current is supplied to the windings through switching
elements 62, the magnetic rotators rotate. Fluid enters the pump
through the opening within thickened wall portion 55 and flows
between vanes 35 and 36 and between vanes 36 and 37, reaching these
areas through vane openings 39 and 40. Since there are no rotator
surfaces to directly force the fluid radially outwardly, as in a
conventional centrifugal pump, friction between the vanes and the
fluid causes the fluid to commence circulating round and round in
circular fashion, and gradually moving outwardly toward the pumping
chamber periphery. The housing has an outlet 64 shown to be more or
less tangential of the chamber periphery, but which may be directed
in any flow direction from the chamber. Fluid the velocity of which
has been increased by rotations of the vanes is caused to move
under pressure out of outlet 64 to accomplish the pumping function
of the pump. Arrow 65 indicates the direction of rotator
rotations.
Referring now to FIGS. 4 and 5 of the drawings, the housing 70 is
of the same general form as housing 48 of FIGS. 2 and 3. A
plurality of vanes 71-74 are disposed within the pumping chamber,
the outermost vane 71 being rotatively sealed by a circular seal
76, for example, an O-ring, and journaled in a suitable ring
bearing. The housing has a thickened wall portion 77 around the
fluid inlet to the pump and the successive vanes 71-74 have
progressively smaller circular flow passages 78-81 affording fluid
flow to between the spaced apart vanes. The vanes are connected by
circularly spaced elements 83 to a rotating magnet body 84. Body 84
carries a concentric shaft 85 which is journaled in bearing 86. The
end 87 of magnet body 84 is flaringly curved corresponding to the
curvature of vane 74 and is spaced therefrom by a distance about
equal to the vane spacings. Magnet body 84 has therearound
alternating north and south poles permanently magnetized therein,
similarly to the magnetic poles of the vanes 35-37 of FIGS. 1 and
2. The connection elements 83 are of streamlined cross section as
is best shown in FIG. 5. The vanes are larger and rounded at one
edge and tapered to a thin edge 89 at their opposite sides. The
rounded edges 88 of the elements 83 are the leading edges which are
impelled through the fluid being pumped and the shapes of the
elements provide streamline flow therearound whereby turbulence is
not caused by the elements 83. The pump of FIGS. 4-5 has imbedded
in housing 70 the windings 89 similarly as the windings 54 are
provided in FIGS. 1-2. The electrical switching elements for the
windings are disposed in a chamber 91 which is provided at the end
of rod or shaft 85. The electrical connections between the
switchings elements and the windings are not shown as they are
conventional in nature. Electrical power is supplied through
electrical leads 92, 93, from a suitable power supply, not
shown.
Referring now to FIG. 6 of the drawings there is shown a motor-pump
structure having a partitioned housing, the rotator elements being
disposed within one chamber of the housing and the magnetic
armature element being disposed in a separate chamber. The housing
100 of the pump shown in FIG. 6 is circularly and curvingly flared
at end 101, inwardly and outwardly. A thickened wall portion 102
surrounds the circular fluid inlet to the pump. A circular flared
vane 103 is sealed and journaled to the pump housing at 104. A
rotative vane member 105 is circularly and flaringly formed and
spaced from vane 103. The opposite side 106 of vane 105 is circular
and flat as shown. The vanes are connected together by a plurality
of circularly spaced rods 108. A rod or shaft 109 is concentrically
connected to vane member 105 and is journaled through bearings 110,
111. At its other end, rod or shaft 109 carries a circular disc
magnet 113 having spaced therearound alternating north and south
poles of permanent magnetism as previously described for the other
embodiments. The magnetic disc 113 is affixed flatly against a
thicker disc 114 which rotates therewith. Rod 109 extends into a
terminal bearing 115. Housing 100 is flat at its end 117. A chamber
119 formed on the end 117 of the housing contains the electrical
switch elements for the motor winding 120 which is disposed as
before within a circular annular chamber of the housing, outwardly
surrounding the magnetic disc 113. Upon supply of electrical power
to the motor windings 120 through the switching elements 119, the
magnetic disc 113, disc 114 connected therewith, and the rotator
elements 103, 105 rotate to pump fluid entering through the passage
within thickened wall portion 102 to flow within vane 103 and
outside of vane 105. The pump, again, has no impeller surfaces
causing fluid thrust radially outwardly within the pumping chamber
so that the fluid is caused to rotate circularly with constantly
increasing radius, to be expelled through outlet 124 from the
housing. The outlet 124 may be designed similar to outlet 64 of the
FIG. 2-3 embodiment.
In FIGS. 7-8, and FIGS. 9-15, there are shown various forms which
the rotators or accelerators for pumping of the fluid may take. The
rotators are shown more or less schematically in the drawings. In
FIG. 7, two circularly flared pumping rotators 130, 131 are
connected by spiral shaped connectors 132, 133 and 134, with vane
or rotator rotation in the direction indicated by arrow 135. The
spiral connectors 132-134 serve to institute circular flow of the
fluid passing between the vanes as the fluid enters through opening
137. The vane rotation causes the fluid to flow in increasing
radius circles to exit at 138, the circular space between the outer
vane edges.
In FIG. 9, there is shown a rotator assembly including trumpet
shaped circular flared rotators 141, 142 which are connected by a
connector 143 of the form of an increasing amplitudes screw
formation. As fluid entering between the rotators at opening 144 of
vane 141 is brought into contact with connector element 143, the
screw shape of the connector impels the fluid to circular flow, the
flow continuing outwardly between vanes 141, 142 to exit from
therebetween at 145.
The vanes in FIGS. 10-15 are of various shapes to indicate rotator
surfaces which are useful in circularly impelling the fluid for
pumping within a pump of the type herein described, the respective
pumping chambers (not shown) being of corresponding interior shape.
In FIG. 10 the vanes 161, 162 are respectively of trumpet shape,
circularly flared, vane 161 having an inlet opening 163, and fluid
is caused by friction with the vanes to move in circles of
increasing radius to exit finally between the outer vane edges at
164. In FIG. 11 the vanes are of hemispherical hollow form, the
outer vane 171 having an inlet opening 172, and the vane 173 being
of continuous spherical shape. In each case, the vanes are
connected together by appropriate rods or other connector elements
such as have been described. The vanes are mounted within a pumping
chamber with appropriate seals and bearing surfaces around the flow
inlet and with appropriate supports for suitable rotations of the
vanes.
Referring now to FIG. 12, the vanes shown are of inconstant
curvature, the vane 181 having a cylindrical tubular inlet 182 and
the vane 183 having a more or less pointed formation 84 to direct
the circularly moving fluid to between the vanes without friction,
the fluid entering at 185 and exiting at 186. In FIG. 13 vane 191
is of truncated conical form, having an inlet at its apex 192, and
the vane 193 being of conical form. Fluid enters at 194 and is
expelled at 195.
The vanes 191a and 193a are similar to those shown in FIG. 13,
except that the conical angle of vane 193a is flatter than the
conical angle of vane 191a, and the vanes are of the same outer
diameter, as shown. In FIG. 15, there are shown three vanes which
are of the circular flared form heretofore encountered, each vane
being thin walled at its inner portion 201, 202 and 203,
respectively, and relatively thicker walled at its outer radial
portion 201a, 202a, and 203a, respectively.
It will be noted that in all of the embodiments shown and
described, the fluid inlet through the housing wall and the initial
vane into the interior of which the fluid passes, are smoothly
merged so that there are not abrupt changes of fluid flow
therepast. In each case, the fluid to be pumped flows inwardly
between rotating accelerator vanes or rotators, to be driven by
friction with the rotators in a circular flow direction. The pumps
operate on a forced vortex principal, there being no impeller
surfaces in the pumps for impelling blood or other fluid material
being pumped radially outwardly toward the periphery of the pump
chamber. A forced vortex pump operates on the principal that a
rotating chamber causes rotation of its contents, with creation of
a vortex, so that a body of circulating fluid is maintained within
the pump chamber by rotation of the rotator vanes at opposite sides
of the chamber. The rotational speed of liquid in the pump is
increased from the center to the periphery of the pumping chamber.
The liquid is withdrawn at the peripheries of the vanes.
It will be seen that the blood or other fluid, such as fluids to be
pumped through an artificial kidney utilizing the pumps, is not
submitted to any substantial agitation by the rotation of the
vanes, or by any other portion of the pump apparatus. There are no
sudden changes in direction of flow through the pumps, all joints
between surfaces being smooth and all surfaces over which the fluid
flows being smooth. Where there are more than two vanes, there are
more than two spaces in which the fluid is rotated and pumped.
According to this invention, the emphasis is on gentle,
nonturbulent handling of the pumped fluid, as is illustrated by the
aforementioned rotating glass of water with nothing to rotationally
accelerate the water but the smooth side of the glass. Yet, the
water after a time rotates with the glass and continues the
rotation as long as the glass continues to rotate.
It will be realized that pumps may be supplied according to the
invention with any number of pumping stages, and may include
individual pumping stages of any of the types mentioned herein, and
in any combination.
In the case of each of the pumps and rotators shown in the
drawings, it will be noted that the rotators are designed to avoid
turbulence and to avoid rapid pressuring and depressuring of the
blood or other fluid, such as kidney fluid, being pumped, and also
to avoid any physical grinding or abrasive action upon the fluid.
As has been made clear, these rotator designs are made in this
manner in order that blood or other delicate liquids or gasses
being pumped, some containing solids in suspension, will not suffer
detriment and will not be destroyed by the pumping operation.
In contrast to centrifugal pumps, the revolution speeds permitted
of the rotators employed with the pumps herein shown and described
are kept minimal. The several rotator designs presented are each of
a form adapted to progressively increase the circular fluid
velocities as the rotator turns and as the fluid advances toward
the periphery of the rotator. In each pump presented, an annular
fluid circulation space is provided which is entirely unobstructed
and regular so that fluid can circulate therein without turbulence
or baffle effects.
Referring to FIGS. 2 and 3 of the drawings, the plural rods 38
spaced about the vanes can be eliminated and the rotators 35 and 36
levitated within the electromagnetic field generated by the
windings of the electrical motor assembly indicated by reference
numeral 54. The rod 43 can also be eliminated and all rotators 35,
36, and 37 would then be levitated in the electromagnetic field
generated by the windings of the electrical motor assembly 54. The
levitated rotators 35, 36, and 37 can all revolve at the same speed
of rotation or each can revolve at a rotational speed independent
of the others. Plural rods 38 or connecting elements 83 (this
latter illustrated in FIG. 5) may be used to join two or more
rotators while the rotators are levitated in the electromagnetic
field generated by the electrical motor assembly 54. In instances
in which multiple rotators are levitated in an electromagnetic
field, two or more rotators may be connected by plural rods 38
(illustrated in FIG. 3) or connection elements 83 (illustrated in
FIG. 5) while one or more additional rotators are levitated and
revolve without being connected to a neighboring rotator. It is
understood that operation and levitation of the rotators within an
electromagnetic field as described can be applied to the various
forms of rotators disclosed herein or in said U.S. Pat. No.
3,487,784.
As hereinbefore indicated, pumps may be made according to the
invention incorporating features from one or more of the preferred
embodiments shown and described herein, any particular feature not
being confined to use only with the other features in connection
with which it is herein shown and described.
The pumps and their parts may be constructed of any materials
compatible with their intended use, including metals, mineral
materials, plastics, rubbers, wood, or other suitable materials.
When blood is to be pumped, consideration must be given to
biological compatibility so that trauma to the blood will not
result. Teflon has been successfully used in contact with blood,
without traumatic effects, and may be used in construction of the
pumps for blood pumping adaptations. Noncorrosive metals and alloys
may be used in the pumps where required.
The housings and rotators may be constructed of suitable material
so that the housing may be rigid, semirigid, or elastic in whole or
in part. The nonrigid constructions can be used for imparting pulse
configurations to blood in heart simulation pumps.
While the rotators shown herein may in some cases perform better
when rotated in one direction, it should be understood that they
may be rotated in either direction i.e., reversed, without other
modification of the pumps. Each of the rotators presents surfaces
to the fluid being pumped, to cause accelerating circular fluid
motion in the pumping chamber. In some cases, the surfaces are
parallel to the fluid flow; in other cases parallel and nonparallel
surfaces are provided. Each of these surfaces, of whatever form,
will accelerate the fluid regardless of the direction of rotation
of the rotator. Each rotator should be rotated at a speed such that
essentially no fluid turbulence occurs, and differences in the
rotator designs affects the maximum speed at which a particular
rotator may be rotated. The physical and flow properties of the
fluid pumped will, of course, also affect the maximum speeds of
rotation at which the rotators may be operated without turbulence
and other objectionable effects, such as cavitation, vapor binding,
and the like. It is, therefore, not possible to set forth exact
rotational speed ranges for the rotators. But, the speeds of
rotation will always be lower and will usually be substantially
lower than those of centrifugal pumps and blowers, wherein
turbulence always occurs as the impellers thrust the fluid radially
outwardly against the periphery of the pumping chamber, and those
of the aforementioned multiple disc pumps and compressors. To the
end of achieving reduced rotator speeds, pumps provided according
to this invention may be of larger size than other pumps, for the
same pumping capacity. As internally placed heart pumps, the pumps
may be as large as 5 inches in diameter, and, with removal of a
lung, even larger.
According to the precepts of this invention, the forms of the
rotators may vary considerably. For example, the rotators may be
constructed entirely or partly of porous or perforate materials,
i.e., the vanes of the rotator which accelerate the fluid
circularly may be made of screen, of perforate plates or sheets, of
spaced rods, or the like, and will still ably perform their fluid
accelerating function. Rotators may be of axially extended form, so
that the fluid is accelerated axially or axially and radially.
Designs of this nature would extend the flowpath from inlet to
outlet so that acceleration would be at a slower rate. In each of
the pumps shown and/or described, one or more tangential outlets
could be provided, disposed in the direction of fluid flow inside
the peripheral wall of the pump. In multistage pumps, the several
rotators, which may be alike or unlike, may be driven at different
rotational speeds. The axes of multistage rotators may be offset
and in other positions out of alignment.
While preferred embodiments of apparatus according to the invention
have been shown and described, many modifications thereof may be
made by a person skilled in the art without departing from the
spirit of the invention, and it is intended to protect by Letters
Patent all forms of the invention falling within the scope of the
following claims.
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