US3437050A - Peristaltic pumping device - Google Patents

Description

April 8, 1969 J. HRDINA PERISTALTIC PUMPING DEVICE Sheet of 5 :iled Jan. 3, 1967 INVENTOR.

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April 8, 1969 J. HRDINA 3,437,050

PERI STALTIC PUMPING DEVICE Filed Jan. 9, 1967 Sheet ,6 of 3 INVENTOR.

Filed Jan. 3, 1967 Sheet 3 PERISTALTIC PUMPING DEVICE IN V N TOR.

I HRDIN A torney sited rates Int. Cl. F041) 43/08 US. Cl. 103148 6 Claims ABSTRACT OF THE DISCLOSURE In a device for peristaltic pumping of a liquid through a hose or another elastic tubular member a straight portion of the tubular member leans against a prop member and is operated upon by a squeezing member at the outflow end of the straight portion temporarily restricting or closing its flow area; in spaced relation thereto a movable pressure member compresses the tubular member on its forward motion towards the inoperative squeezing member and on its return movement releases the tubular member while the squeezing member is operative. Timely coordinated cams with associated leverages effect and control the cooperation of the squeezing member and of the pressure member.

The present invention relates to an improved method of pumping liquids through elastic, more particularly small-diameter tubes or hoses, and an apparatus for carrying out this method.

A common feature of many processes generally used in various laboratory techniques is the necessity of transporting liquids from a vessel to another through one or more elastic, more particularly small-diameter tubes or hoses. One of the problems connected with the said procedure, however, is to secure the proportionality of fiow rate in individual tubings. Two principal types of so called peristaltic pumps are well-known and conventionally used for the punpose.

The first of the peristaltic pump types as hereinbefore set forth comprises two or more pressure rollers caused to revolve along a circular path, which rollers press one or more elastic hoses spaced in juxtaposition on to an internal, or external cylindrical surface of a support member the elastic hose bears upon and to which it is secured. The pressure rollers are mounted on a carrier member adapted to rotate about an axis which is identical with that of the thrust zone of said cylindrical supporting surface. Between the circumferential portion of said rollers and said thrust zone there is left a clearance which is predimensioned so that the elastic hose, due to a squeezing action of the pressure rollers, is distorted on its cross section, whereby its opposite walls adhere to each other along the nip line and block the flow of liquid in the hose. Thus the hose cavity is partitioned by the roller nip into two sections. Said squeeze of the elastic hose by the pressure roller rolling therealong is not released until another pressure roller in trail establishes the next squeeze so that any free passage for the liquid flowing through the elastic hose within the whole length thereof never occurs in fact, even for a short time interval. By locally squeezing the elastic hose up to complete choke it is secured that the liquid therein will be pushed at a speed directly proportional to that of the rolling motion of the pressure roller as herinbefore set forth.

The second type of peristaltic pumps is analogous to the lastmentioned with the exception that it comprises plurality of pressure rollers rolling in a similar manner along one or more elastic hoses spaced in juxtaposition on a flat surface, the rolling movement of the pressure "atent O 3,437,950 Patented Apr. 8, 1969 rollers accomplishing a peristaltic effect upon the elastic hoses, which movement is derived from a suitable driving means by the intermediary of for example two endless Galls chains led over two pairs of sprocket wheels, respectively, one pair thereof being positively driven.

In order to choke up completely the elastic hose by deforming it on its cross section the distance between the pressure rollers exerting a peristaltic thrust upon the elastic hose and the stationary flat surface supporting one or more elastic hoses has to be selected, with both of the peristaltic pump types as hereinbefore set forth, so that upon a peristaltic deformation of the hose the flow therein may be blocked with a sufficient security reserve without giving rise, however, to excessive pressure-s causing a relatively short lifetime of the elastic hose due to an overstrain of the material it has been made of, resulting from high squeeze frequencies. In some cases, particularly when using one or a reduced number of elastic hoses, this drawback can be overcome by Ibiassing the pressure rollers so that they may exert an appropriate resilient pressure on the elastic hose, or, the other way about, that a springloaded plate bears upon a set of rigidly mounted rollers to cause an appropriate hose distortion. An important condition to be met with the lastmentioned practice, however, consist in that the wall thickness of all the elastic hoses used has to be alike.

An essential drawback of the apparatus hereinbefore set forth consist in that it is very difficult to achieve a precise control of hydraulic pressure in the elastic hoses. Substantially it is possible to mo'dilficate the transflux through the hose by jump only, that means by replacing a hose for another one having a different diameter but approximately the same wall thickness. In this way it is possible to achieve an appropriate deformation of the hose up to the complete choke without being necessary to adjust the distance between the pressure roller exerting a peristaltic pressure upon the elastic hose, and the cflat surface of said stationary support. A rolling speed control of the peristaltic pressure rollers is not recommendable since it is, with the difficulties to be met with the construction of such an apparatus in view, rather problematic, lets not say impossible, particularly with such apparatuses possessing an advantage that consists in that by a single pressure element more than one elastic hose are peristaltically deformed.

All the hereinbefore said drawbacks of the previous art can be eliminated by using the improved method of pumping liquids through elastic, more particularly small-diameter tubes or hoses according to the present invention in that a flowing liquid column of a given, preferably adjustable length is perista-ltically advanced through one or more elastic hoses by predetermined strokes produced by always a single peristaltic pressure roller caused to roll under a suitable thrust therealong, and in that after the rolling movement having been finished the elastic hose is squeezed by another squeeze element for a time period during which the elastic hose is out of engagement with said pressure roller which in this period is returned to its initial position where it is ready again to start its peristaltic action.

For carrying out the above-mentioned method of pumping there have been designed an apparatus comprising one or more elastic hoses adapted to be deformed on their cross section with the aim to interrupt the flow of the liquid therein by the peristaltic pressure roller, or the squeeze element, which apparatus is characterized in that the elastic hoses are squezzed alternately by thrust of the single peristaltic pressure roller rolling therealong within a predetermined path defined by two disengagement positions, on the one hand, and of the squeeze element, on the other hand.

The operating length of the path of the peristaltic pressure roller as well as the thrust of the same and/or the squeeze element upon the elastic hose can be adjusted by suitable means.

Similarly, one set of cams and levers to cause movements of the operating parts as well as one peristaltic pressure roller and/ or one squeeze element can operate a plurality of elastic hoses.

The said and other objects of my invention will be more fully understood from the following specification when read with the accompanying drawings in which FIG. 1 is a schematic showing indicating the principle of operation of my new device,

FIG. 2 is a front view partly in section of an embodiment of my new device,

FIG. 3 shows an amended detail in a front view partly in section, and

FIGS. 4, 5 and 6 show in front view partly in section H other amendments.

The hose or other elastic tubular member 1 made of silicone rubber or any other suitable elastic material is pressed against the flat surface 3 of a prop body 4 by a roller 2 which can move along the hose 1 exerting a peristaltic pressure thereupon. The roller 2 is rotatable on shaft 6 which is mounted on the free end of a draw rod 5, its other end thereof being linked at 7 to one arm of the crank lever 8 which oscillates on the stationary pivot 9. The other arm of crank lever 8 holds at its end the follower roller 10 which cooperates with the cam 11 being permanently forced against its surface by the spring 13. The cam 11 and other cams hereinafter to be mentioned, such as cam 25, are fixed to a common shaft 12 which is driven by a not shown electric motor.

The shaft 6 carrying the press roller 2, or a number of such rollers each cooperating with one of a plurality of hoses, also additionally supports one or more guide rollers 14 moving on the flat surface 15 of a thrust plate 16 which is supported by swing arms 19, linked thereon by the pivots 17, 18 and turnable on the stationary pivots 21, 22. Arm 19 forms a crank with arm 23 which carries at its free end a follower roller 24 held by not shown means in permanent engagement with cam 25 on shaft 12. Still another not shown third cam on shaft 12 engages permanently the follower roller 27 mounted at the free end of arm 26 which is swinga'bly mounted on the stationary pivot 28 and rigidly associated with the hooked arm 29 whose nose 30 is adapted to squeeze the elastic hose 1 as shown. The cams cooperating with the follower rollers 10, 24, 27 are properly shaped and associated to insure the required chronological action of roller 2, of thrust plate 16 and of the squeezing nose 30.

The before described apparatus shown in FIG. 2 will operate as follows in accordance with the schematic showing in FIG. 1 to which reference is made hereinafter:

FIG. 2 illustrates the device at the start of the operational cycle. The elastic hose 1 which receives fluid in the direction of arrow 70 is squeezed by the nose 30 of arm 29 and the pressure roller 2 is raised by thrust plate 16 and its follower roller 14 in the direction of arrow E in FIG. 1 from a disengaged position into a position strongly compressing the hose 1 and closing its cross sectional area. Thereupon the not shown cam acting upon follower roller 27 causes the nose 30 to release its squeeze as indicated by arrow H in FIG. 1 and cam 11 causes the pressure roller 2 to move to the left along the hose 1 as indicated by arrow F in FIG. 1. After termination of this lateral movement of the pressure roller 2 the hose 1 is again squeezed by the nose 30, the thrust plate 16 together with its follower 14 and pressure roller 2 is moved away from hose 1 as indicated by arrow C in FIG. 1 and pressure roller 2 is returned into its initial position as indicated by arrow D in FIG. 1 by the associated action of cam 11, follower roller 10, crank lever 8 and draw rod 5.

To permit access to the hose 1 and to the members cooperating therewith the prop block 4 may be tiltably mounted in stationary bearings 33, 34 by means of pivots 31, 32. One pivot 32 and possibly also the other pivot 31 may support a holder 35 provided with a guide channel 36 for the hose 1 which is positionally secured by the latch 37 adjustably attached by screw 38 to holder 35. The prop member 4 may preferably be made of a translucent material to permit observation of the hose 1 during the peristaltic operation.

FIG. 3 shows a section in a plane passing through the axis of shaft 6 in an embodiment permitting concurrent operation on several hoses 1, 1, 1", particularly of different diameter. To this effect the surface 3 of the prop member 6 is staggered as shown. The guide roller 14 cooperating with the thrust plate 15 is designed as a roller bearing and so can be the pressure roller 2 and the link 39 of draw rod 5 and shaft 6.

FIG. 4 shows in a front view partly in section a detail of the device illustrated in FIG. 2 modified to permit adjusting the length (L in FIG. 1) of the peristaltic motion of the pressure roller 2 along hose 1. The draw rod 5, or each of a plurality thereof, is linked at 7 to an arm 40 swingably mounted on the stationary pivot 9 which also supports the swing plate member 41 with roller 10 forced against and engaging cam 11 by the action of spring 52 leaning against the stationary prop 51. The arm 40 is loaded by a spring 43 leaning against prop member 44 on swing plate 41 and is pressed in clockwise direction to lean against the stop member 42 on plate 41 so that the lateral movement of the draw rod 5 with pressure roller 2 conforms to the movement of the plate 41 as if they would be rigidly connected. If, however, the upper end of arm 40 possibly provided at the joint 7 with an abutting roll 45 contacts the adjustable stop member 46 controlled by screw 47, the swing movement of arm 40 will be arrested in a predeterminable position while plate 40 will continue the swing around pivot 9 compressing spring 52 against the stationary stop 51. The adjusting screw 47 penetrates the nut 48 which is preferably slit and can be tightened by the bolt 49. The nut 48 or possibly a plurality of them is mounted on a stationary bar 50. It will be understood that the adjusting screw 47 will control the lateral move of the pressure roller 2 and thus its peristaltic action upon the elastic hose 1 between a maximum and zero.

FIG. 5 shows another modification of the embodiment illustrated in FIG. 2 to permit the nose 30 to exert an adjustable squeezing force upon the elastic hose 1. The nose 30 on arm 29 does not act directly on the hose but through another intermediate lever 53 oscillatable on stationary pivot 54 and provided with the squeezing nose '55. The nose 30 acts against a leaf spring 56 secured to lever 53 by screw 57, said leaf spring being supported and biased by an abutment member 58 with screw 59 which can be positionally adjusted as indicated by arrow 61 within the elongated slot 60 in arm 53.

FIG. 6 shows still another modification of the embodiment illustrated in FIG. 2 permitting adjustment of the pressure of roller 2 upon hose 1. The draw rod 5 bearing the pressure roller 2 in linked by pivot 62 to a swing lever 63 carrying the guide roller 14 actuated by the surface 15 of thrust plate 16. The pressure of roller 2 upon hose 1 results from spring 64 which is attached to arm 63 by screw '65 and is adjustable by the grub screw 66 in lug 67 of draw rod 5. The distance between rollers 2 and 4 determines the bias range of spring 64 and can be adjusted by screw 68 in lug 69 of rod 5.

What we claim is:

1. An apparatus for peristallic pumping liquid through at least one elastic tubular member comprising in combination (a) at least one elastic tubular member having at least partially a straight portion, and a prop member therefor;

(b) a squeezing member temporarily restricting the outflow area in said straight portion;

(c) a pressure member in spaced relation to the squeezing member laterally movable along said straight portion in pressing position towards the squeezing member and in distanced position in a return motion;

(d) first cam means and a first leverage associated with the pressure member to press the same against the tubular member while being moved towards the squeezing member and to distance the same from the tubular member while returning;

(e) second cam means and a second leverage associated therewith actuating the squeezing member for temporary action;

(f) the first and second cam means and their leverages being timely coordinated to effect the peristaltic pumping action by releasing the squeezing member while the pressure member compresses the tubular member during its motion towards the squeezing member and by positively actuating the squeezing member while the pressure member returns in a position disengaged from the tubular member.

2. A pumping device according to claim 1 compris-i ing a draw rod within the first leverage;

a thrust plate pressing the pressure member to the tubular member; and third cam means with a third associated leverage acting upon the thrust plate;

the third cam means with its third leverage being timely coordinating with the first and second cam means and their leverages to alternately press and release the pressure member on its forward and return movement.

3. A pumping device according to claim 2 comprising first cam means and first leverage means including a spring loaded crank lever having two arms;

one arm bearing a follower cooperating with the cam means;

a draw rod attached with one end to the pressure member and with its other end to the other crank lever arm;

the second leverage having two rigidly associated arms, a follower at the end of one crank arm and at the end of the other crank arm a nose forming the squeezing member.

4. A pumping device according to claim 1 comprising a draw rod attached with one end to the pressure member and with its other end to a swing lever oscillating about a stationary pivot;

5 a plate member freely swingable about said pivot and bearing a follower for cooperation with the first cam means;

first spring means ensuring cooperation of said follower with said first cam means;

a stop member on the plate member t arrest the turning movement of the SWlIlg lever and second spring means on the plate member initiating such turning; and adjustable stop means for the other end of the 1 draw bar to limit the turning of the swing lever.

5. A pumping device according to claim 3 comprising a lever having a nose at its end interposed between the other crank arm and the tubular member and an adjustable spring on said lever cooperating with the nose of the other crank arm.

6. A pumping device according to claim 2 comprising a draw rod attached with one end to the pressure member and with its other end to the first leverage;

a secondary lever articulated with one end intermediately to the draw rod and hearing at its other end a guide member slidable on the thrust plate;

spring means between the draw rod and the secondary lever forcing the guide member against the thrust plate;

and adjustable stop means acting upon the secondary lever to limit the resulting action of said spring.

References Cited 3 UNITED STATES PATENTS 473,546 4/1892 Carroll 103 -149 2,412,397 12/1946 Harper 103148 3,083,647 4/1963 Muller 103-148 3,292,667 12/1966 Bittner et a1. 103149 40 3,359,910 12/1967 Latham 103-449 ROBERT M. WALKER, Primary Examiner. W. I. GOODLIN, Assistant Examiner.

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