U.S. patent number 3,622,252 [Application Number 05/027,316] was granted by the patent office on 1971-11-23 for roller pump with lubricating channels for rollers.
This patent grant is currently assigned to Extracorporeal Medical Specialties, Inc.. Invention is credited to Robert E. Pickup.
United States Patent |
3,622,252 |
Pickup |
November 23, 1971 |
ROLLER PUMP WITH LUBRICATING CHANNELS FOR ROLLERS
Abstract
A roller pump of the type having a flexible tubular pumping
chamber continuously and successively depressed unidirectionally by
traveling rollers wherein means is provided for directing cleaning
and/or lubricating fluids to the bearing surfaces of the rollers to
reduce wear and unnecessary "drag" on the tubular pumping chamber
and insure that the longitudinal tension in the tubular chamber
does not exceed a value which prevents lateral flexure and causes
pumping action to continue rather than "by-pass" when a resistance
of predetermined magnitude is encountered.
Inventors: |
Pickup; Robert E. (Norristown,
PA) |
Assignee: |
Extracorporeal Medical Specialties,
Inc. (N/A)
|
Family
ID: |
21836981 |
Appl.
No.: |
05/027,316 |
Filed: |
April 10, 1970 |
Current U.S.
Class: |
417/477.3;
384/391; 417/477.13 |
Current CPC
Class: |
F04B
43/1215 (20130101) |
Current International
Class: |
F04B
43/12 (20060101); F04b 043/08 (); F04b 043/12 ();
F04b 045/16 () |
Field of
Search: |
;417/474,475,476,477
;418/45 ;308/113,115 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Croyle; Carlton R.
Assistant Examiner: Gluck; R. E.
Claims
While the above described embodiment constitutes the presently
preferred mode of practicing this invention, other embodiments and
equivalents are included within the scope of the actual invention,
which is claimed as:
1. A pump comprising a base, a drive shaft mounted for continuous
rotation relative to the base, a power driven rotor comprising a
plate portion, an axial apperture in the plate portion for
receiving one end of the drive shaft, a detent arrangement for
releasably securing the rotor to the drive shaft, and a plurality
of pumping members secured to an eccentrically spaced on the rotor,
each pumping member including a spindle secured at one end to the
plate portion of the rotor and having an outer bearing surface, a
tube-contacting roller having an inner bearing surface mounted on
each spindle, a resilient tube anchored between an inflow station
on the base and an outflow station on the base and stretched around
the pumping member rollers so that it is otherwise unsupported
between the inflow station and the outflow station, and channel
means comprising a hole in each spindle communicating at one end
with the bearing surfaces and at the other end with the atmosphere
on the opposite side of the rotor to minimize the possibility of
contaminants associated with the roller side of the rotor from
reaching the bearing surfaces via the hole, the hole being of a
diameter susceptible of receiving cleaning and/or lubricating
fluids from a source such as a hypodermic needle for delivery to
the bearing surfaces.
2. A pump as in claim 1 wherein the rollers each have first and
second axially spaced tube-contacting portions, each such portion
having a convex tube-centering configuration.
3. A pump as in claim 2 wherein the inner bearing surface of each
roller is generally cylindrical, and each roller is machined from
polyoxymethylene.
Description
BACKGROUND OF THE INVENTION
The claimed invention relates to the field of power driven pumps
used to convey fluids wherein the fluid being pumped is forced
through a flexible tubular chamber by pumping members mounted for
travel in unidirection depressing contact with the tubular chamber.
Pumps of this general type are capable of a wide variety of uses,
but are particularly useful in pumping sensitive fluids--such as
blood, parenteral infusion liquids, and the like--at slow,
carefully controlled rates and pressures in critical environmental
settings such as those encountered in the medical profession.
Prior to the present invention, pumps of this general nature have
been used for many years. Arnold U.S. Pat. No. 2,406,485
illustrates the basic principle of using a flexible tubular pumping
chamber stretched over triangularly arranged rollers on a power
rotated head, and the most advanced type of such pump heretofore
commercially available is disclosed in my U.S. Pat. No. 3,502,034.
Pumps of this type, where the tubular pumping chamber is not
trapped against an outer wall but is simply stretched around the
pumping members and is otherwise unsupported, have a "relief valve"
feature which is advantageous in many instances. If the fluid being
pumped meets with abnormally high resistance, such as a clogged
line downstream from the pump, the flexible pumping chamber is
capable of expanding despite the continuing rotation of the pumping
members, and the lateral expansion will permit the pumping action
to be discontinued preventing rupture of the system. As one
example, when a pump of this nature is utilized to deliver fluid to
a patient in an intravenous feeding operation, it occasionally
occurs that the filter downstream of the pump becomes clogged with
material which apparently crystallizes out of the fluid being
pumped, and pumps of this type will discontinue pumping action when
a resistance of predetermined value builds up rather than
continuing the pumping action and driving the undesirable
crystallized material through the filter and into the patient.
One problem with pumps heretofore available, however, is that this
"relief valve" feature is erratic and unpredictable, and the pump
may discontinue its pumping action in the desired fashion against a
resistance of predetermined value on one day, but on the next day
will undesireably continue pumping against a greatly increased
resistance. It is believed that this is due in part to the rollers
of the pumping members "freezing" on their spindles, as by
contaminants clogging the bearing surfaces, which causes the stuck
roller to drag on the inflow portions of the tubular pumping
chamber. This is believed to create longitudinal tension in the
tube to the point where its ability to flex and expand laterally,
and thereby bypass fluid to be pumped, is inhibited. Rollers which
lock on their spindles also create other equally serious problems,
such as increased wear on the tube. If the pump drive is equipped
with a low-torque safety clutch, moreover, jammed rollers can
create sufficient drag that the clutch activates, permitting the
pumping rotor to stop while the drive motor continues unimpeded,
resulting in motor burn-out. If the pump is a battery operated
unit, the increased drag caused by rollers which do not turn freely
draws excessive power and reduces the battery cycle causing the
unit to fail prematurely-- which the patient can ill-afford if
replacement batteries are not readily at hand.
Prior attempts to solve this long recognized problem and insure
that the pumping rollers turn freely on their spindles make use of
the obvious expedient of utilizing more expensive bearing
equipment. For instance, Santiago U.S. Pat. No. 1,988,337 and Jones
U.S. Pat. No. 2,334,148 disclose the use of ball bearings;
Moulinier U.S. Pat. No. 2,483,924 and Ballentine U.S. Pat. No.
3,402,673 disclose the use of sleeve bearings; and, Jensen U.S.
Pat. No. 2,696,173 discloses the use of collar bearings. All these,
however, are susceptible of clogging and jamming, for instance,
when fluid being pumped or other contaminants get into the
bearings, and they are extremely difficult to disassemble and
clean. Thus, these expedients do not get at the heart of the
problem of providing means to insure that the pumping rollers turn
freely to overcome the aforementioned difficulties.
Thus, the problem heretofore unsolved by the prior art is the
provision of simplified means for directing cleaning and/or
lubricating fluids to the bearing surfaces of the rollers to reduce
wear on the tube and insure that the "relief valve" feature of the
pump functions predictably rather than erratically.
SUMMARY OF THE INVENTION
This invention provides a roller pump of the type having a
resilient tube anchored between an inflow station and an outflow
station and at least one pumping member mounted for travel in
unidirectional depressing contact with the tube along a portion of
its length, the pumping member including a traveling spindle having
an outer bearing surface, a tube-contacting roller having an inner
bearing surface mounted on the spindle, and channel means for
delivering cleaning and/or lubricating fluids to the bearing
surfaces. The channel means comprises a hole in the spindle which
communicates at one end with the bearing surfaces and at the other
end with the opposite or "clean" side of the rotor to receive
cleaning and/or lubricating fluids from a source such as a
hypodermic needle for delivery to the bearing surfaces. To this
end, the rotor is releasably secured to the base by a spring-loaded
detent arrangement so it can easily be removed and held upside-down
while the cleaning and/or lubricating fluids are applied.
BRIEF DESCRIPTION OF THE DRAWINGS
Numerous advantages of the present invention will become apparent
to one skilled in the art from a reading of the detailed
description in conjunction with the accompanying drawings wherein
similar reference characters refer to similar parts and in
which:
FIG. 1 is a front perspective view of a roller pump according to
this invention;
FIG. 2 is a fragmentary plan view showing the positioning of the
pumping rollers on the pump of FIG. 1;
FIG. 3 is an enlarged fragmentary sectional elevational view on
line3-3 of FIG. 2 showing the channel means in the spindle of a
pumping member; and,
FIG. 4 is a fragmentary view of a pumping member held upside-down
for the application of cleaning and/or lubricating fluids.
DETAILED DESCRIPTION
Referring in more particularity to the drawings, the roller pump
unit 10 illustrated in FIG. 1 comprises a main housing 12 having an
instrument panel 14 secured to the front face and a foldable handle
16 secured to the top. The main housing 12 contains an electrically
powered drive motor, a speed reduction gear box, optionally a
low-torque clutch, speed indicating mechanisms, and other related
controls which per se form no part of the present invention. A
rotatable drive shaft 18 protrudes vertically upwardly through the
top of the housing 12 for connection with the pumping member rotor,
as explained below.
Mounted on top of the housing 12 is pump head 20 which comprises a
lower tube anchoring block 22 on one side, an upper tube anchoring
block 24 of the other side, and therebetween a power driven rotor
26 having three eccentrically spaced pumping members 28. The lower
tube anchoring block 22 holds both ends of a resilient pumping tube
30 which in turn is connected to an inflow conduit 32 and to an
outflow conduit 34. The upper tube anchoring block 24 holds both
ends of another resilient pumping tube 36 which in turn is
connected to an inflow conduit 38 and to an outflow conduit 40.
Details of the construction of the tube anchoring blocks 22, 24 are
disclosed in my aforesaid patent 3,502,034 to which specific
reference is made for details of the inflow station 42 and outflow
station 44 on the upper tube anchoring block 24 and the inflow
station 46 and outflow station 48 on the lower tube anchoring block
22.
The rotor 26 comprises a single circular plate portion 50 with an
upstanding central boss 52 having an axial aperture 54 to receive
the upper end of the power driven shaft 18. A spring loaded detent
arrangement 56 in the boss 52 laterally engages as at 58 the upper
end of the shaft 18 to prevent accidental axial displacement of the
rotor 26 from the shaft 18. The aperture 54 in the rotor includes a
flat 60 or other keyway arrangement which cooperates with a
corresponding flat 62 on the shaft 18 to insure that the rotor and
the shaft turn together. The aperture 54 in the rotor does not
extend through the top of the upstanding central boss 52, which may
have a smooth upper surface preventing any accidental leakage of
fluid along the shaft 18 and into the housing 12.
The three pumping members 28 take the form of rollers or spools 64
having generally cylindrical inner bearing surfaces 66. The rollers
are mounted for free rotation on spindles 68 having generally
cylindrical outer bearing surfaces 70. The spindles 68 are
preferably of stainless steel, and are mounted eccentrically of the
shaft 18 on the upper side of the flat plate portion 50 of the
rotor, such as by a reduced diameter shank portion 72 received with
a press fit in a suitable vertical aperture in the plate portion 50
and flared outwardly as at 74 to engage a countersunk portion of
the aperture on the lower side of the plate portion. The rollers 64
are preferable machined from polyoxymethylene, such as the
commercially available "Delrin", to provide first 76 and second 78
axially spaced tube depressing portions, each portion having a
convex tube centering configuration. The lower convex portions 76
insure that the lower pumping tube 30 is properly mounted in a
lower plane perpendicular to the rotor axis and spaced slightly
below the upper parallel plane occupied by the upper pumping tube
36 trained around the upper convex portions 78 of the rollers
28.
Each pumping member 28 includes channel means for delivering
cleaning and/or lubricating fluids to the bearing surfaces 66, 70.
The channel means comprises a hole 80 in the spindle 68
communicating at one end 82 with the bearing surfaces and
accessible at the other end 84 to the atmosphere in the zone where
each spindle is secured to the rotor so as to be accessible to a
source of fluid, such as a hypodermic needle. Preferably, the lower
end 84 of the hole communicates with the atmosphere on the opposite
side of the rotor from the rollers 64 to minimize the possibility
of contaminants from the pumping tubes reaching the bearing
surfaces. The hole 80 extends generally axially of the spindle from
the lower end 84 thereof to a point near the bearing surfaces 66,
70, and then extends laterally of the spindle to communicate with
the bearing surfaces as at 82.
The pumping tubes 30,36 are similar, although tubes of different
diameters may be utilized to pump two different fluids at two
different rates simultaneously. The pumping tubes are preferably
molded to length of silicone rubber, and are extremely resilient
having ability to expand and permit the "relief valve" feature
described above. For pumping low volumes of fluid, the portions of
the tubes contacted by the roller may be molded of smaller diameter
than the ends of the tubes which cooperate with the slots at the
inflow and outflow stations, as is apparent. When two tubes 30, 36
are employed and anchored in the opposite blocks 22,24, unbalanced
lateral stress on the rotor axis is minimized or eliminated, and
each roller 64 rotates constantly about its spindle 68 insuring
that it is rotating with the proper peripheral speed each time it
moves into contact with the inflow portion of a pumping tube.
In operation, power operated rotation of the rotor 26
(counterclockwise in FIG. 2) serves to move fluid through the
pumping tubes 30,36 pumping it from the inflow conduit 46 to the
outflow conduit 48, and from the inflow conduit 38 to the outflow
conduit 40, respectively. At the end of each period of use,
especially if there is a likelihood that contaminants or other
foreign matter may have seeped into the bearing surfaces 66, 70
between the rollers 64 and the spindles 68, it is a simple
matter--after removing the pumping tubes 30, 36--to grasp the rotor
26 and remove it axially from the drive shaft 18. Holding the rotor
upside-down, see FIG. 4, cleaning and/or lubricating fluids may be
applied by a hypodermic needle 90 to the inlet end 84 of the hole
80 for delivery as at 82 to the bearing surfaces. A-15 through -18
gauge blunt end hypodermic needle may be used for this purpose. If
the pumping members are particularly clogged or jammed, a cleaning
fluid such as alcohol or acetone may first be injected to flush out
the contaminants. A lubricating fluid such as castor oil has been
found particularly useful for insuring that the polyoxymethlene
rollers 64 turn freely on the stainless steel spindles 68.
There has thus been disclosed a means for insuring that the rollers
of the pumping members turn freely on their spindles, minimizing
the various problems created by rollers which tend to "freeze" on
their spindles.
* * * * *