U.S. patent number RE28,742 [Application Number 05/215,221] was granted by the patent office on 1976-03-23 for pumps capable of use as heart pumps.
Invention is credited to Harold D. Kletschka, Edson Howard Rafferty.
United States Patent |
RE28,742 |
Rafferty , et al. |
March 23, 1976 |
Pumps capable of use as heart pumps
Abstract
The disclosure is of pumps which are 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.
Inventors: |
Rafferty; Edson Howard
(Minneapolis, MN), Kletschka; Harold D. (Minneapolis,
MN) |
Family
ID: |
26909831 |
Appl.
No.: |
05/215,221 |
Filed: |
January 3, 1972 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
Reissue of: |
678265 |
Oct 26, 1967 |
03487784 |
Jan 6, 1970 |
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Current U.S.
Class: |
415/90;
128/DIG.3; 415/100; 415/216.1; 415/900; 604/151; 604/6.11 |
Current CPC
Class: |
F04D
1/06 (20130101); F04D 29/22 (20130101); A61M
60/422 (20210101); A61M 60/82 (20210101); A61M
60/205 (20210101); A61M 60/122 (20210101); A61M
60/148 (20210101); A61M 60/818 (20210101); A61M
60/40 (20210101); F05B 2200/15 (20130101) |
Current International
Class: |
A61M
1/10 (20060101); F04D 29/22 (20060101); F04D
29/18 (20060101); F04D 1/06 (20060101); F04D
1/00 (20060101); F04D 001/14 (); F01D 001/14 () |
Field of
Search: |
;415/90,76,213
;416/178,180 ;128/DIG.3,1D |
References Cited
[Referenced By]
U.S. Patent Documents
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247,106 |
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539,373 |
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577,051 |
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May 1924 |
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FR |
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980,672 |
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FR |
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331,142 |
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Jun 1930 |
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UK |
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599,519 |
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DD |
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361,209 |
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Oct 1938 |
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IT |
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866,706 |
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May 1941 |
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FR |
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159,785 |
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Mar 1921 |
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538,658 |
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Aug 1941 |
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UK |
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814,564 |
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472,199 |
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IT |
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268,028 |
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Jul 1950 |
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CH |
|
Primary Examiner: Raduazo; Henry F.
Attorney, Agent or Firm: Merchant, Gould, Smith, Edell,
Welter & Schmidt
Claims
What is claimed is:
1. Pumping apparatus for use in pumping fluids susceptible to
damage from turbulence and shock, comprising housing means having
central fluid inlet means and peripheral fluid outlet means,
rotator means disposed for rotation within said housing means and
having surface means for accelerating fluid in substantially
circular motion without said housing means as said fluid flows
between said inlet means and said outlet means, means for sealing
between said housing and rotator centrally about said inlet means
and around the periphery of said rotator means, said inlet means
including port means through said rotator means at the rotative
axis thereof opening toward the periphery of said housing means,
said surface means of said rotator means comprising plural parallel
surfaces substantially each parallel to the planes of circular
movement of said fluid passing through said housing means from said
inlet means to said outlet means, said plural parallel surfaces
being spaced at least one-fourth inch apart, said rotator means
being adapted to rotate at a speed such that fluid passed thereto
from said inlet means is caused to rotate circularly at
substantially the speed of said rotator means, whereby turbulence
and shock to said fluid in passing from said inlet means to said
outlet means is avoided.
2. Pumping apparatus for use in pumping fluids susceptible to
damage from turbulence and shock, comprising housing means having
central fluid inlet means and peripheral fluid outlet means,
rotator means disposed for rotation within said housing means and
having surface means for accelerating fluid in substantially
circular motion within said housing means as said fluid flows
between said inlet means and said outlet means, means for sealing
between said housing and rotator centrally about said inlet means
and around the periphery of said rotator means, said inlet means
including port means through said rotator means at the rotative
axis thereof opening toward the periphery of said housing means,
said surface means of said rotator means including at least one
surface parallel to the planes of circular movement of said fluid
passing through said housing means from said inlet means to said
outlet means and at least one other surface angular to said one
surface, said rotator means being adapted to rotate at a speed such
that fluid passed thereto from said inlet means is caused to rotate
circularly at substantially the speed of said rotator means,
whereby turbulence and shock to said fluid in passing from said
inlet means to said outlet means is avoided.
3. The combination of claim 2, each said other surface being curved
between the center and periphery of said rotator means for
elongating the paths of fluid flow therebetween.
4. The combination of claim 2, said surface means including at
least one circular band shaped surface concentric with said
rotator. .Iadd. 5. Blood pumping apparatus, comprising:
a. housing means defining a chamber;
b. rotator means disposed for rotation within said chamber of said
housing means and including at least two coaxial, spatially
separated, smooth surfaced rotative vanes having axially spaced
surfaces for accelerating blood introduced into the spatial
separation between said vanes in a substantially circularly outward
direction;
c. inlet means positioned within said housing means for introducing
blood into the spatial separation between said rotative vanes
generally along the rotative axis thereof;
d. outlet means positioned peripherally within said housing means
for removing the outwardly accelerated blood;
e. means for rotating said rotative vanes at a speed such that the
blood introduced into the spatial separation between said vanes is
caused to rotate circularly at substantially the speed of said
spatially separated vanes preventing turbulence and shock to the
blood as the blood moves circularly outward between said inlet
means and said outlet means; and
f. said rotative vanes being spaced apart a sufficient distance in
relationship to the area of their surfaces in contact with the
blood, said distance being on the order of one-fourth inch and
greater, to minimize shear stresses imposed on the blood by
frictional contact with the vane surfaces while maintaining a body
of blood circulating within the chamber to provide a forced vortex
radially increasing pressure gradient pumping action.
.Iaddend..Iadd. 6. Pumping apparatus for use in pumping fluids
susceptible to damage from turbulence and shock, comprising:
a. housing means defining a generally cylindrical chamber;
b. rotator means including at least two smooth surfaced circular
accelerator vanes disposed for simultaneous rotation within said
cylindrical chamber and positioned in a spatially separated
relationship for accelerating fluid introduced into said spatial
separation in an essentially circularly outward direction, at least
one of said circular accelerator vanes defining a generally
centrally positioned passageway therethrough, said surfaces being
spaced at least one-fourth inch apart;
c. fluid inlet means positioned within said housing means for
introducing fluid through said passageway in said accelerator vane
into said spatial separation between said vanes generally along the
rotative axis thereof;
d. fluid outlet means positioned peripherally within said housing
means for removing the outwardly accelerated fluid from said
cylindrical chamber; and
e. means for rotating said accelerator vanes at a speed such that
the fluid introduced into said spatial separation between said
vanes is caused to rotate circularly at substantially the speed of
said vanes so as to prevent turbulence and shock to the fluid in
passing circularly outward between said inlet means and said outlet
means. .Iaddend.
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. 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.
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, it has been found that use
of centrifugal pumps invariably results in physical disruption of
the blood and at least some of its 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, without any significant destruction of the
blood and its components resulting from the pumping.
SUMMARY OF THE INVENTION
The invention is of rotative pumps which are suitable for use in
primary blood 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, 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 cross sectional view of one preferred form of pump
according to the invention.
FIG. 2 is a partial cross sectional view showing a modification of
the pump of FIG. 1.
FIG. 3 is a cross sectional view of a three-stage pump, according
to the invention.
FIG. 4 is a cross sectional view of a modified form of pump
according to the invention.
FIG. 5 is a partial cross sectional view taken at line 5--5 of FIG.
4.
FIGS. 6-8, 8A, and 9-12 show different forms of fluid accelerators
or rotators which may be employed in pumps according to the
invention; FIG. 9, in addition, shows a built-in drive motor for
the accelerator or rotator.
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 diastrolic
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 non-turbulent
flow is maintained through the pumps, and the pumped fluid 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. As 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 clip or
shear between radially adjacent particles of water, and the water
radialy 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.
Referring first to the apparatus shown in FIG. 1 of the drawings, a
housing 15 has parallel spaced circular walls 16, 17. At the center
of wall 16, an offset chamber 19 is formed which terminates
outwardly in an inlet passage 20. Wall 17 has at its periphery
circular formations 22, 23 joined by peripheral wall 24 between
which is formed a peripheral ring-shaped chamber 27. Formation 22
is internally shaped to provide a flow-direction flaring surface
28. Wall 16 is connected to formation 22 by a plurality of
circularly spaced screws 29.
A rotative circular vane 31, forming one side of the accelerator or
rotator 30, has at one side a flared inlet formation 32 which
extends into chamber 19 and is sealed to the wall of chamber 19 by
O-ring 34 and which rotates in bearing 35 disposed within chamber
19. The interior wall of inlet 32 is flush with the wall inlet 20.
An O-ring 36 around the periphery of flat vane or disc 31 seals
with the inner side of formation 22. The inner side of vane 31 is
flush with the beginning of curved surface 28 so that fluid flowing
through the pump introduced through entrance 20 flows smoothly from
entrance 20 to entrance passage 32, through the pump chamber, and
smoothly past the intersection of the periphery of vane 31 and
surface 28.
Vane 31 is connected to a second rotating vane 38, forming the
other side of accelerator or rotator 30, which is concentric and
parallel to vane 31, by circularly spaced pins or rods 39. Vane 38
has O-ring 40 about its periphery to seal with the inner side of
formation 23. An outlet passage 41 is provided at one side of wall
member 17, it being possible to provide any number of such outlets
circularly spaced about the pump as is desired. Wall 17 has at its
center a central passage 43 containing bearing 44 which is in
contact with rotating shaft 45 connected to, or forms a part of,
vane 38. Vane 38 has at the center of its inner side the rounded
projection 38a, which guides incoming fluid to flow smoothly along
the vanes.
The pump shown in FIG. 1 operates in the following manner: The
fluid to be pumped flows inwardly through passage 20 into passage
32 to the space between rotating accelerator vanes 31, 38. Shaft 45
is driven rotatively by means not shown, and vanes 31, 38 rotate
together (in either direction) because of their connection at pins
or rods 39. The pump operates on a forced vortex principal, there
being no impeller surfaces in the pump 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 vanes 31, 38
at opposite sides of the chamber, whereby the rotational speed of
liquid in the pump is increased from the center to the periphery of
the chamber of the pump. The liquid is withdrawn through the outlet
41, and as has been stated before, a plurality of outlets 41 may be
provided if desired.
It will be seen that the blood or other fluid passing through the
pump 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 the flow through the pump,
all joints between surfaces being smooth and all surfaces over
which the fluid flows being smooth.
Referring now to FIG. 2 of the drawings, there is shown a portion
of a pump identical to that shown in FIG. 1 except that the flow
outlet is of modified form. The outlet 41a from the pump chamber is
shown to be disposed radially from the pump chamber instead of
parallel to the pump axis as in FIG. 1. The wall elements 16a, 17a
are like those shown in FIG. 1 except that the curved surface 28 is
omitted at the interior of formation 22a and the peripheral chamber
27a is of rectangular cross section. The vanes 31, 38 are as shown
in FIG. 1, as is also the remainder of the pump, only the
peripheral portions of the pump elements being modified as shown.
The operation of the pump in FIG. 2 is the same as that of the pump
of FIG. 1, except that the pumped fluid exists from the pump
radially instead of in line with the pump inlet. Plural outlets 41a
may be provided if desired.
Referring now to FIG. 3 of the drawings, there is shown a pump 50
having three serially disposed pumping stages, whereby the pressure
of blood (or other fluid) pumped may be higher than the pressure
obtained in a single stage of pumping, such as by the pumps shown
in FIGS. 1 and 2. The pump housing is made up of housing elements
51, 52, 53 and 54. The housing elements are joined at peripheral
bolt flanges 55-56, 57-58, 59-60, the bolts not being shown.
The pump of FIG. 3 has three pumping chambers 61a, 61b, 61c, and
two return chambers 62a, 62b through which the fluid pumped by the
first two pumping stages is returned to the center of the pump for
the next pumping stage.
The rotator or accelerator 63 in pumping chamber 61a includes a
flat circuit vane 64, having peripheral flange 65, and sealed to
the housing for rotation therein by O-ring seals 66, 67, and a flat
circular vane 68 spaced from vane 64 and supported by plural
circularly spaced pins or rods 69, and mounted at its center on
shaft 70.
The return chamber 62a is formed between circular plate 71 and
housing wall 52a, plate 71 being supported by wall 52a through
plural circularly spaced pins 72, and sealed to the periphery of
vane 68 by O-ring 73. Vane 68 and plate 71 are of the same
diameter. Shaft 70 is disposed for rotation through plate 71 at
O-ring seal 74.
The rotator or accelerator 75 in pumping chamber 61b includes vanes
76, 77 which are identical with vanes 64, 68, respectively, except
that shaft 70 extends completely through vane 77 as shown. The
seals 66, 67 and rods 69 are provided as before. Rotator 75 differs
from rotator 63, however, in that a plurality of relatively thin
flat plates or sheets 78a-78c are spaced parallelly between the
facing sides of vanes 76, 77 within the pumping chamber. Plates
78a-78c are circular and may be of the same or different diameters.
They are supported at perforations therethrough by the pins 69
extending between vanes 76, 77. Any number of these plates may be
provided, so long as the spacings therebetwen do not become small.
The spacings between the adjacent vanes and plates should not be
less than about 1/4 inch. If the vanes and plates are spaced more
closely, the shear stresses imposed on the blood or other fluid
become excessive, with resulting trauma of blood and harmful
physical effects in the case of other fluids. In Transactions of
the ASME, July 1963, page 205, it is stated in the second complete
paragraph of column 2, that in pumps therein termed "shear-force
pumps," that "Due to the necessity for very close spacing of the
shear surfaces, the pump" (ed) "fluid must be essentially free of
suspensions." It should be made clear at this point that the
utilization of very close spacings is not contemplated by this
invention, so that the invention is distinguished over the
apparatus described in the aforementioned article, and also is
distinguished over apparatus of the type or kind proposed in Patent
No. 1,061,206 to Tesla. In such apparatus, the emphasis is on very
high rotational velocities and very close spacings, which make them
unfit for use insofar as the contemplation of this invention is
concerned. According to this invention, the emphasis is on gentle,
non-turbulent 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.
Return chamber 62b is identical with return chamber 62a, and
includes elements 71a, 53a, 72a, 73a, 74a, respectively identical
with elements, 71, 52a, 72, 73, 74 heretofore described.
The rotator or accelerator 80 is made up of vanes 81, 82 which are
respectively identical in form with vanes 64, 76 and 68, 77. The
rods 69 are omitted, and the vanes 81, 82 are connected by plural
vanes 83, radially disposed and arcuately spaced. The vanes 83 may
be flat as shown, or may be curved end-to-end and twisted like the
vanes shown in FIG. 9. Any suitable number of vanes 83 may be
provided. Each vane 83 extends from near the axis of the pumping
chamber to terminate the line with the inner face of vane 82, as
shown.
Within housing element 54, there is a ring-shaped chamber 85
disposed between circular walls 86, 87, 88, walls 87, 88 being
aligned with the sides of the annular opening between vanes 81, 82.
Outflow opening 89 is provided through wall 88, and plural such
openings may be provided if desired.
Shaft 70 is rotated by means not shown to rotate the vanes of the
three rotators.
The flow inlet to the pump is provided through nipple 51a and
circular opening 64a aligned flushly therewith.
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 in
any combination.
Referring now to FIGS. 4 and 5 of the drawings, there is shown a
pump 110 having a housing made up of members 112, 113 identical
with the corresponding housing members of FIG. 2 except that
bearings 135 is in a different disposition than bearing 35 (see
FIG. 1). Elements of FIGS. 1-2 which are the same as indicated by
the same reference numerals in FIGS. 4-5. The accelerator 119
includes a flat circular vane 120 and a second flat circular vane
121. The vanes 120, 121 are connected by the full-radius curved
vanes 125, and the shorter curved vanes 126, 127, and 128. As best
shown in FIG. 5 of the drawings, the vanes 125 extend from the
center of the accelerator to its periphery, the vanes 126 extend
from a point spaced from the center of the accelerator to its
periphery, and the vanes 127, 128 extend from about the centers of
vanes 126 to the periphery of the accelerator. Four of each type of
vanes are shown in the drawing.
The objective of this configuration of the vanes is that the
impetus of the vanes in thrusting the pumped fluid outwardly is
minimal, only four of the sixteen vanes acting on the blood, or
other fluid, as it emerges from the entrance into the pump chamber,
and, as the blood progresses through the blood chamber, from its
center toward the periphery, additional vanes take action to move
the blood in its spiral motion, with increasing velocity, toward
the periphery of the pumping chamber.
The rotator 119 has a flared entrance 130 which merges smoothly
into the face of vane web 120. The interior of entrance 130 blends
smoothly with the interior of entrance 20 which is formed in the
offset space 19 at a side of the housing.
At the opposite side of the housing, wall 113 has at one side a
cylindrical formation 134 through which rotative shaft 135 is
disposed within bearing 136, and O-ring seal 137 is disposed about
the outer periphery of vane 121 to seal between the vane and
housing.
The housing has at one side the radially disposed outlet 138 having
outflow passage 139 therethrough. Any number of similar outlets may
be provided.
A ring shaped screen 140 is disposed around the ring shaped space
27a of the apparatus of FIGS. 4-5, the screen dividing the space
into inner and outer annular portions. The screen may be omitted.
Any porous or perforate divider may be substituted for the screen,
e.g. a plate having one or more openings, spaced bars, etc. The
screen serves to create two distinct annular flow zones within
space 27a, an inner zone in which the fluid moves circularly as
accelerated by the rotator, and an outer zone reached by the fluid
by outflow through the screen, over its complete circular length,
the fluid flow through the screen reducing its circular velocity.
Thus, the outer zone is a zone of slower velocity from which the
fluid moves in the outlet 139, whereby eddy currents and turbulence
at the outlet is reduced.
Referring now to FIGS. 6-12, there are shown a number of forms of
rotators or accelerators which may be used in the pumps, these
being shown more or less schematically. The rotators 141, 142 shown
in FIGS. 6 and 7 are similar, each having a pair of curved blades
or vanes 150-151 and 153-154, respectively. The views shown are
cross sections taken at right angles to the axis of rotation of
each rotator, and the rotator shown in FIG. 6 has a flat side plate
or vane 155 which is circular, and similarly the accelerator shown
in FIG. 7 has a side vane or plate 156, also circular. In most
cases there will be another plate 155 or 156 at the other, or near,
side of the vanes. The rotators, therefore, are enclosed at their
sides by these plates. The rotator of FIG. 6 has central openings
158 where the liquid to be pumped enters, and a pair of flow
passageways between the vanes indicated by reference numerals 159,
160 which are of constant cross section from the center to the
periphery of the rotator. Fluid passing through this rotator does
not have opportunity for volume expansion, as the flow passages,
through which it moves are of constant size from their beginning to
their end. The rotator of FIG. 7, on the other hand, has the pair
of flow passages 162, 163 extending from the center to the outside
of the rotator which increase in cross section from their central
entrance to their peripheral outlet ends.
The rotator shown in FIG. 8 consists of a hollow, drum-like, body
165, having a cylindrical tube 166 between central openings at each
of its sides, and having a curved peripheral wall 167. The tube 166
and wall 167 have plural openings 168, 169, respectively, any
suitable numbers and spacings of these being provided, four of each
being shown circularly equally spaced. Fluid enters through tube
166 and flows into the drum through openings 168. The drum is
rotated and the fluid therein is caused to rotate, the rotator
giving the fluid circular motion but no outward radial motion.
Centrifugal force resulting from circular motion of the fluid,
however, causes the motion of the fluid to be spiral instead of
circular, so that the fluid after moving spirally through the space
within the drum flows outwardly through the openings 169 into the
pumping chamber space annularly around the rotator, from which the
fluid exits through one or more outflow passages of any suitable
form. A pair of O-ring seals 170, 171 disposed in suitable grooves
around the opposite edges of the body 165 seal between the rotator
and the pump housing in the manner shown in other drawing
figures.
In FIG. 8A, a rotator is shown which is a modification of that
shown in FIG. 8, and to which the description of FIG. 8 applies to
the elements indicated by the reference numerals of FIG. 8, the
modification residing in the addition of the tubes 173, each of
which extends between one of the inner holes 168 and one of the
outer holes 169 at the same side of the rotator. The tubes 173 may
be straight and radial as shown in the drawing, or may be curved or
angular, by proper positions of the holes 168, 169 and shaping of
the tubes. In this rotator, the fluid would pass from tube 166
through tubes 173 to exit at the periphery, upon rotation of the
rotator.
Referring now to FIG. 9 of the drawings, a rotator 175 is shown
which has a plate or disc 176 at each of its sides which may be
identical or of different form or size, only one being shown in the
drawing, and between which there are provided the equally
circularly spaced curved blades 177a-177h, 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 a propeller. The
blades or vanes, may extend beyond the outer edges of the discs
176. Each blade 177a-177h carries a winding 178, which is covered
by an impervious layer or membrane 179. The blade windings are
connected to contact elements of a commutator 180. The surrounding
pump housing is provided with the circularly spaced magnets or
coils 181, which are separated from the pumping chamber by an
impervious layer or membrane 182. 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 rotator of FIG. 9, it will be understood
that it may be provided in conjunction with all of the other forms
of rotators disclosed herein.
The descriptions concerning power supplies to the motor of FIG. 9
will, of course, relate also to power sources for motors connected
to pump shafts external of the pump housings.
Referring now to FIG. 10 there is shown a rotator in the form of a
plate 185, the peripheral edge 186 of which is of corrugated
formation. The radial corrugations each extend narrowingly to the
center opening 187 of the plate. The curved corrugation surfaces
are adapted for acceleration of fluid circularly as the rotator is
rotated, in either direction, about its center. This form of plate
may be used alone as a rotator, or plurality as the flat plates of
the second stage of the pump shown in FIG. 3. Similarly, the flat
vane surfaces, such as in FIGS. 1 and 2, may be corrugated to
enhance their accelerative purpose. Rotators of this form present
only smooth surfaces to the blood or other fluid being pumped.
In FIG. 11, there is shown an accelerator or rotator having spaced
parallel circular plates 190, 191 at the inner side of each of
which are provided circularly spaced radial vanes 192 and 193. The
vanes 192, 193 are staggered as shown, the vanes of each plate
190-191 being alternately disposed and extending only partway
toward the opposite plate 190 or 191.
Referring now to FIG. 12 of the drawings, the rotator therein shown
has a pair of opposite sides vanes or plates 197, only one being
shown, between which are disposed a plurality of circularly spaced
curved vanes 198. These vanes are of a shape, when rotated in the
direction of arrow 202, serve to pick up blood from the entrance
203 to move it into the rotative path of the vanes, and then the
concave curves of the vanes act to accelerate the fluid circularly
while restraining somewhat outflow toward the periphery of the
rotator, and at the same time lengthening the flow paths of the
fluid from the center to the periphery of the rotator.
In each of the pumps shown in FIGS. 1-5, and pumps wherein use is
made of rotators (or accelerators) of the different forms shown in
FIGS. 6-12, 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 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 gases 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 revolutions per minute 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.
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. Non-corrosive metals and
alloys may be used in the pumps where required.
In the embodiment of FIG. 9, Teflon may be used for the membranes
179, 182 covering the windings of the electric motor
structures.
The housings and rotators may be constructed of suitable material
so that the housing may be rigid, semi-rigid, or elastic in whole
or in part. The non-rigid 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
non-parallel 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 at 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 five 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 the
rotator of FIG. 7, the vanes could be made to become closer
together, instead of farther apart, toward the periphery of the
rotator. 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 multi-stage
pumps, such as that shown in FIG. 3, the several rotators, which
may be alike or unlike, may be driven at different rotational
speeds. The axes of multi-stage 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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