US2544628A - Peristaltic pump - Google Patents

Description

March 6, 1951 B. G. COPPIN G PERISTALTIC PUMP Filed June 15, 1946 IN V EN TOR.

c H GM 5 w m 5. Y O B Patented Mar. 6, 1951 PERISTALTIC PUllIP Bruce G. Capping, Fulton County, Ga, assignor to The Coca-Cola Company, Wilmington, Del., a corporation of Delaware Application June 15, 1946, Serial No. 676,929

13 Claims. 1

This invention relates to pumps, and more particularly to a new and improved peristaltic pump.

Heretofore, sundry devices of this general type have been proposed, such generally contemplating the use of a block of rubber or rubber tube which is in some manner alternately compressed and extended to exert a pumping action on fluid contained in an opening or passage in, or adjacent the rubber element, the purpose of such pump being to eliminate the close machining, tight seals and multiplicity of parts characterising pumps of the gear displacement type. Unfortunately, however, it does not appear that these pumps have been commercially successful, the rubber therein usually wearing out at a rate which makes them impractical for any prolonged use. The chief factor in this wear is that of heat, and accordingly, it has been necessary to resort to expensive gearing down if such pumps are to be at all usable, the providing of speed reducing apparatus entailing additional cost and resulting in limited transfer of the fluid being handled.

An object of my invention is to provide a peristaltic pump which consistently operates at high speeds with small, inexpensive motors of standard design.

Another object is to provide longer life in such a device.

Another object is to make possible a wide variety of operating characteristics including those of high discharge pressure, and very low suction pressure in such a pump.

in Fig. l, the right half of the pump being shown in vertical cross-section; and

7 is an outside mounting ring, the two co-operating A still further object is to provide simplicity of construction and therefore cheapness of manufacture in a peristaltic pump.

Another object is to make possible economy of operation of sucha device.

Another object is to provide ready accessibility to the parts of such a pump which are most'likely to wear, thereby facilitating repairs when such are necessary.

Another object is to provide self-sealing means in a pump of the instant type.

Another object is to provide an automatic safety valve in a peristaltic pump.

These and other objects made apparent through the further progress of this specification are accomplished by means of my peristaltic pump, a full and complete understanding of which is facilitated by reference to the drawing herein in which:

Fig. 1 is a view in side elevation of the pump mounted on a motor, the upper half of the pump being illustrated in vertical cross-section;

Fig. 2 is an end elevation of the pump shown in a manner explained hereafter. I4 is an innerring assembly consisting of a sleeve and innerfiange l5, and a press on outer-flange l6, and Ilia. is an inner sleeve which is bonded strongly to the inner diameter of rubber element II. I! isan eccentric, mounted in conjunction with eccentric bearing [8. Elements l9 are main fastening screws holding together the pump assembly.

20 is the end-bell of a motor 2|, to which the pump proper is attached through mounting screws 22. 23 indicates the motor shaft, which is positioned in operative relationship to motor shaft bearing 24.

A tension relief hole 25 is cored through the rubber pumping element I I, the function and operation of which aperture will be explained in detail at a later point in the instant specification.

26 is an inlet port through which a fluid (either liquid or gas) enters the pump proper, and 21 is the outlet port through which such fluid is ejected after having passed through and been boosted by the pump.

28 is a blow-by barrier, which will also be described and explained at a later point herein.

In assembling my peristaltic pump, stator ring it], rubber pumping element II, with the associated sleeve Ilia; inside mounting ring l2, and outside mounting ring [3, are clamped together into an assembly by means of the four main fastening screws l9. The relative dimensions of these parts are such that when the assembly is made, the inside mounting ring l2 and the outside mounting ring l3 serve to tightly clamp the pumping element l I hermetically to the stator ring III. In this connection, it will be noted that elements l2 and I3 are providedwith sloping faces I20. and [3a, which mate with corresponding sloping faces on element i l, and as the assembly is pulled together not only is said rubber element pressed inwardly and sealed against stator ring ill, but it is also drawn outwardly against such ring. This wedge action has the advantage of not only providing a more secure seal, but it also prevents any inward displacement of the rubber resulting from the squeezing-up action of the pumping operation.

Inner assembly 14 is likewise firmly clamped to the inner periphery of rubber pumping element II, this clamping being eifected by having the outer flange l8 form a press fit on the sleeve l5, said outer flange being pressed on .to said sleeve with sufficient force as to givethe desired clamping action against the inner periphery of pumping :pump; and to its.continued-life- -tnat the fastening of the pumping element tothe stator and to i3the1inner rmgassembly 14, be very secure; and

the means illustratedin the drawingfor accom- 1 'plishing this result are by mechanical clamping.

. Such; clamping may. be supplemented, however, by binding orgcementingpthe rubber, to all adjoiningmetal parts, or it ispracticalinsome ap- :plication, to substitute cementing or bonding .material .for the; mechanical clamping ,method which. is .showntherein for illustrative purposes.

Advantages of .the instant arrangement lie in readydissembly, of .the pump and replacement of .anyworn .or broken.v part in a minimumof 1 time. Life tests to .date indicate, however, that replacement ofanypartsis likely toberequired at infrequent intervals.

. Continuing further 1 with :the instant assembly,

bearing its is pressed into the sleeve and inner flange .l5,.and in turn eccentric llis fitted into the innerdiameter of said eccentric bearing, the

eccentric, itself, being mounted on the end of motor. shaft .23. Hence,-it-is apparent that when said motorshaft rotates the eccentric ll,.act

ing through its associated bearing-willcause theinnerringiassemblyito generate an eccentric motion, and since lthe -inner ring assembly is rigidly .fastenedto the inner periphery-:ofthe pumping. element H such eccentric motion is iandmust-be translatedto the inner-part of said elasticcement ll.

-In this connection-reference is now specifically directed toFig. 3 of the drawing, where-itwill be seen that the eccentricmotion'of the inner part of the rubber pumping element will result inthe .inside pumping face of saidelement II ,beingautomatically drawn away from and then -;pressed against the-pumping face =-30 of the .stator ring 10. It'-is further apparent that; due to the eccentric nature of the motion, this squeezing action between the rubberand metal .pumping .faces will advance progressively and .rotatively in thedirection-of the rotation of the .motor,: as suggestedby-the arrow on -Fig.-2-0f-the idrawing; thus setting up a peristaltic action which results in a'fluid being-drawn into the device through inlet port 26 and carried around anddischarged throughoutlet port 21.

Referringagainto-Fig. 3, it will be noted that the pumping face of the'rubberelement, when notdistorted-in either direction by the eccentric,

is flat; and deflection accordingly takes placein bothdirections from the flat position shown by wtheisolid line of the drawing. Maximumout- =..ward deflection is suggested -by the' curveddotted line of the figure and the concave shape of the pumping face 30 of the stator ring i is so dimensioned that it permits a full inward defiection of the pumping face 29 of H, minus a small factor which is provided to allow the rubber to squeeze up tightly against the pumping face 38 of ring I0. This concave shape of the pumping face of the stator .ring is important, in that it increases thecross-sectionatarea of the opening very substantially, thereby increasing xthe capacity of the pump; and what is possibly .moreimportant, also permits the inward deflection of the rubber without undue distortion '..thereof. This factor, resulting in reduction of heat, and-hencein greatly increased life of the rubber-elementand the pump itself.

Consideration is now directed to the specific shape of said pumping element II, it being apparent that the portion 3! thereof which forms the base and stem of the Y suggested heretofore siderableimportance.

is,;.provided: witha ina-rrowed; sectiom 32, and the width; across. :thispection; relativeqto the Width of ;;pumping -,f-ace' 29. and to the width of, the rubber ..;;gripped in thfigillllG]? ring assembly M isof con- The width .Of said nar- ,-row;section';,32 =is; preferably slightly less than that I of; :the, pumping, face .129; so; that zwhenthe eccentric draws. the rubber. away from .this point ,as; establishedwhen .the element; is; in. a fneutral position, the ;motion is :taken up,in-, -the bending :of therubber at the outeredgesgof .the pumping rface, =.;and little-actual stretchingmfthe, rubber 1 accordingly ,-.ocours. Upon; analysis, :it .will 1 be cseencthat;if. se.ction;:32 -':were. made as wide or wider :than :the :pumping ,fa,ce,.x-:it; would -mean 1.,that,,;there:wo111d 'occuna, stretchingof the rub- ;bce itself; atithe.outsideedges, iresultingiboth in ,.--severe; stress;- on; the; rubber itself, .and' .on the ;-:connectionpbetween therubbenand stator ring 4 2 :llL-withundesirable iheat and-:wear.. consequences as pointedoutsheretofore.

IlilhflSzBlSObBBILfOllIld possibleto control the -gmaximumpumping pressuresof the pump by controlling-.sthe width. of .:this .narrow section 32 'relative to;the.;width...of :the pumping face. JFcr example, it will be seen that if said neckssection :.-.:is made Very: .narrow, 1 as icompared with the pumping face, there will be areas atthe outer edgerofysaid face-.where the :rubber. does not have ;the,direct.pressure of .athe eccentric squeezing it eagainstxthe pumping face-filliof. the stator ring,

and when this occurs;thepnly-resistance -to a .cbackward'zfiowior leakage of. the liquid or gas ibeing .handleclzbycthezpump isby virtue of the 5 hardness or elasticity 20f l-the rubber itself. By

warming; the Widthc'Of: section: 32 and byusing rubbers of various hardness and elastic charac- ;ter.is tics,:. .ithas been found practicable to build -:pumps .which azwill .idevelop pre-determined maximum. pressures at which pressures the fluid being pumped overcomes the resistance-of the .:-.rubbers..at: ithesouter edges Y of the pumping" surfaces and blows -by,-,thus creating an automatic .zsafetyrvalve in the-purnp by-means of which it protects itself- .against"destruction in the event .of a blockage of discharge.

The widthof 'theinner periphery, of the rubber pumping element which-is clamped toqthe iinner ring assembly 14' ismadewider than the width of section 32. This isan important feature in that it provides for a slight; flexing of -that part of- -the-rubber which is clamped in the inner ring assembly, which 'fiexinghas .been found essential gin preventing relative motion "between "the'flanges of said inner ring assembly and that portion of the pumping element II which they grip. Any such relative motion between the inner ring assembly and the rubber pumping element results in a rapid wearing away of the rubber, and accordingly, the peculiar cross-sectional shape of the pumping element as described herein and arrived at only through considerable experimentation and research, is of great importance in securing a pump of satisfactory characteristics, including particularly, but not limited to long life.

Finally, it will be noted that adjacent to the points where element II is gripped by surfaces I511 and Heb, there is formed generally circular cut-out portions 32a which provide relief pockets at these points into which the rubber of base member 3!, and to a lesser degree narrowed section 32, may displace durin the pumping operation, this having been found desirable in preventing wear at these points.

.A blow-by barrier 28 (Fig. 2) is provided between the inlet and outlet ports, the purpose of this barrier being to prevent fluid from short circuiting across between the inlet and outlet and negativing the effectiveness of the pump. Said barrier 28 is provided by forming element H with a wedge-like rubber projection which fits snugly into a complementary notch formed in the inner surface of stator ring l0, and when the assembly is clamped up the squeezing action of the inside mounting ring i2 and the outside ring l3 causes the rubber to expand in the barrier notch, thus effecting a hermetic seal against undesired short-circuitin of fluid.

A tension relief hole 25, which is also an important feature of the instant pump, is made necessary by the blow-by barrier 28, since at this particular point the eccentric motion or the pulling away motion of the rubber is firmly resisted by the above described gripping of the barrier in stator ring 10. Tension relief hole 25, however, provides a means for eliminating this direct pull on barrier 28, it being apparent that at this point, the pulling away motion only results in the deformation of the tension relief hole with a consequent relief of stress on the barrier itself.

It will be noted that a feature of the instant pump resides in the fact that when not running, it is automatically self-sealing, eccentric I! and associated structure so bearing on pumping member H as to always press a portion of the inner face 29 of said pumping member against concave face 30 of stator ring l0, thereby effectively blocking and sealing the fluid passage at such point. The advantages of this arrangement are at once obvious to those skilled in the pumping art, and the broader field of hydraulics.

From the foregoing, it is apparent that I have disclosed and described a new and unique peristaltic pump which not only will develop a very high pressure on the discharge side, but also a pump having a positive suction, the weight of the walls of the rubber pumpin element H, coupled with the forced suction resulting from the pulling away action caused by the eccentric, making it possible for this pump to draw very high vacuumas for example, in excess of twenty-nine (29) inches of mercury.

That my pump will handle liquids of all viscosities and gases with equal facility.

That its design is such that the fluid being pumped does not come into contact with the rotative elements and therefore no expensive or costly-to-maintain, power-consuming seals are required.

That this pump works with good efficiency at I rotative speeds as high as 3,500 R. P. M., thus permitting direct coupling to small motors of standard design.

That a wide range of performance characteristics are made possible in my pump through dimensional changes in the rubber pumping element and/or changes in the characteristics of the rubber or other material from which this element is fabricated.

That it is possible to design this pump to a maximum operating pressure upon which fluid will simply blow by and thereby act as an automatic safety valve, this feature making it unnecessary to equip the pump with the conventional spring-loaded by-pass which is a costly and not always satisfactory feature of many small pumps.

That the instant peristaltic pump is susceptible to extreme cheapness in manufacture, all

parts being of such a nature that close machining tolerances are not necessary, it being possible and practical to make all parts of the pump except the eccentric bearing by such economical manufacturin processesas stamping, molding, or die-casting.

While I have disclosed and described herein one embodiment of my invention, such action is not to be taken as limiting in any way, but on the contrary is purely illustrative, it being intended that the appended claims shall be interpreted, and given a construction and scope fairly in keeping with my contribution to the art.

I claim:

1. In a device of the character described, in combination, a source of power, and a pump operatively engaged therewith, said pump comprising a rigid stator ring of generally T-shaped cross-section, a flexible circular pumping element of approximate Y-shaped cross-section mounted adjacent said ring, an inner ring assembly securely engaging the lower portions of said Y-shaped pumping element, an inlet and an outlet for the pump, and an eccentric engaging said inner ring assembly, movement of the eccentric alternately compressing and expanding the pumping element, thereby driving a fluid through the pump.

2. In a device of the character described, in combination, a source of power,'and' a pump operatively engaged therewith, said pump comprising an outer circular stator ring, an inner rubber pumping ring, an aperture in said pumping ring, means for alternately compressing said pumping element against the inner surface of said stator ring and drawing said pumpin element away from said surface, an inlet and an outlet for the pump, and a blow-by barrier formed integral with the pumping element and seating in a notch formed in the inner peripheral dimension of said stator ring, the barrier automatically disengaging itself from the notchat a pre-determined pressure, permitting fluid being handled by the pump to blow by a such time.

3. In a device of the character described, in combination, a source of power and a pump operatively mounted therewith, said pump comprising a circular metal stator ring of generally T-shaped cross-section, a flexible circular pumpin element of approximate Y-shaped cross-section disposed in sealed relationship with said stator ring, an eccentric positioned. within 7 sis-aidzimunpingzzelementtand inzcontactitherewith, an inlet and an outlet for the pump, movement mic-the;:eccentricscausing" athe pumping zelement .tobet progressively .zcontracted: and. expanded, .ztherebyzimpellingi a:fiuid through :the; pump.

4. In a device of the characterzdescribed,;in .combination, :7: a. source of ppower, sand a 1: pump :1 pperatively. engaged therewith,r-said'cpumpr com- -;prising arstator ring of generally T-shaped crossiazsention -arzrubber:ipumpingtelement; associated .;..therewith,.:said pumping elementhavings an approximate Y-shaped orosse'se.ction-,-'and aneccentrictmounted-hdiaceht said-pumping; element, an :inletzand: anoutletufor;the pump; the movement ofithe-=eccentrica;causing:theipumpingielement to he progressivelylcompressed andexpanded, there- -=by iimpellingea Lfiuid through :the pump.

ii 5; In a device of thecharacter described 'in combinatioma'source of -power; and a pump operatively engaged therewith, said pump comprising a rigid stator ring, a "-fiexib'le circular pumping element ofapproximate Y-shaped cross-section mountedadjacent-said ring, an inner ring assembly securely engaging-the lower portions of said Y-shaped pumping element, and an eccentric -operatively-engaging said inner =-ring assembly, an-inlet and an outlet for the ruimninovement of the eccentric alternately compressingand-expandingthe pumping element, thereby driving a "fiuid through'the pump.

' 6. 'In ahdevice-ofthe characterdescribed, in combination; asource-of-power, and a pump operatively engaged therewith, said pump comprising a stator ring; a:flexible circular pumping element of generallyY-shaped cross-section mounted adjacent said ring, an inner ring assembly-securely engagingthe lower portionsof said pumping ele- =ment, and an eccentric operatively engaging said *inner'ring assembly, aninlet and an outlet for the pump; movement of the eccentric alternately compressing and expanding the pumping element, therebydriving-afiuid through the pump.

7:111 a-device of the character described, in combination, :a source of power, and a pump operatively engagedtherewith, .said pump comprisinganouter circularJstator ring, an inner rubber'pumping ring a' tension relief holein saidpumping ring, means, for alternately compressing-said pumping element against'the inner surface of said stator ring and drawing .said 'pumping element a'way 'from'said surface, an inlet 'and'an-outlet for the'pump, and afwedgeshapedblow by barrierpformed'integral with the "pumping element and seating in a" notch formed inthe inner peripheral dimension'of said stator ring, the? barrier automatically disengaging itself 'fromthe notch at pre-determined pressures, per- 'mittingfluid'being handled bythe pump to blow by atgsuch :time.

.In a device of thecharacter described, in combination, a source of power, and a pump -operatively engaged therewith, said pump .com-

prisingyan' outer'circular stator ring, an inner rubber pumping ring, means for alternately compressing said pumping. element against the inner "surface -ofsaid-stator ring and "drawing said pumping element away from said surface, an inlet and'an-outlet-for the pump, and, a'blow-by barrier formed integral with the pumping ele- "ment and' seating in' a-notch formedin the inner 5 such :time.

.9. in a--:devic,e of the character described, a rubber peristaltic piston, comprising .a ring of generally v-shapedrcross-section, the :stem of a the -Y= being narrowerthan thezupper arms there- 10 of, ;there.-being. sloping anchoring surfacesz-cn said arms ran inletiand an outlet communicating --with saidipiston'; means; including a central-eccen- ;fcr.--motivati'ng :said pistonga circular-stator Jllilg surrounding said-piston, and meansrhermeti- T, cally sealing the-outer peripheralmarginstofv the piston, 1,With the stator ring, said; means. com- 1;prisingitwocasing;halves, and meansfonsecuring -*s'aid :halves. together andzagainst the. outeripedges :;of: said .rubber: piston.

10. In a device-pf thecharacter described, a

--riibberrperistaltic, pumping element,- comprising ;a:-ring"of:;genera11y -Y -shaped cross-section, .the rstemgoffthe lbeing lnarrowerqthan the upper arms thereof; anzinlet and an outlet communicating withisaid pumping element,; means including ea; central; eccentric for. motivating said element, arstator ring surrounding s'aid; pumping element .candu being: hermetically sealed thereto, a: groove 1 in ,.said: stator ring, and. a: peripheralugroove :in

:.rsaid pumping 1element,,. aid .latter groove :00-

operating with the.- groove. of :the stator ring in pumpingiliquid :by :peristaltic' action.

.. 1 1c- Azflexiblepumping element=for.a peristaltic pump, comprising a circular ring :of generally i-shapedz cross-section, the. stem of the Y being narrower rthan .the upper. arms thereof.

12. in. a: device for pumping fluid .bya peristal- -:.tic-like "actiomra grooved flexible pumping ele- ;;.ment, means forisubstantially deflecting only the iOzbottonrof the groove. to squeeze fiuidprogressively in the groove: and means confining the flexing of zxthe: pumping elementuto substantially only :the :imme'cliateportionof the groove"- being acted upon :1 by uz aidz first. mentioned means -during agiven ,;,,-,::.phase..of: thezpumping operation.

:13. In; apdevice tofu the character described, a rubber pumping element comprising a circular rubbersring; of generally "Yeshaped cross-section, :a;blowebyloarrier..formed integral .with said ring onrthe; outer peripheral. .edge thereof, and a ieniSiOn mhef! tho-1e formed .inhthe. rpumping :element adjacent said safetybarrier; an inlet and an outv let ;.--communicating .with=.:said pumping-element, ;a:nd."i.means1..or.. automaticallyv compressing and 55.1distending: said element. to :effect vpumping rby .peristaltioaction,whereby aaxminimum of stressing and zdistending of, said rubber epumping elemerit .isc-present in establishing and maintaining such action.

IQBRUCE GMCOPPING.

. REFERENCES CITED "The?following-references are of record :in the i filelofthis patent: (in

1 UNITED STATES PATENTS Number Name Date 765,360 1 Baumann June 24, 1930 2,246,488 Fraser Junel'l, 1941 2,251,235 Weyde'll July 29, 1941

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