US2915983A

US2915983A - berrian

Info

Publication number: US2915983A
Authority: US
Publication date: 1959-12-08
Anticipated expiration: 1976-12-08

Description

Dec. 8, 1959 J, H, BERRlAN 42,915,983

TUBING PUMP Filed Aug. 10, 1956 Amie.-

BY wf Wa@ ATTORNEY United States Patent TUBING PUMP James H. Berrian, Bethesda, Md.

Application August 10, 1956, Serial No. 603,453

Claims. (Cl. 103-149) (Granted under Title 35, U.S. Code (1952), sec. 266) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

The present invention relates to tubing pumps and more particularly to a tubing p-ump in which a section of tubing is progressively compressed by a rigid surface so that a relatively steady flow is obtained.

'Various sorts of tubing pump devices which are capable of the same general function as the present invention are prevalent in the prior art. In these devices the contents of a tube are forced to ow -by means of rollers, screws, lingers or cones brought to bear upon the tubing, but these devices, while capable of low speed operation, were not designed for and are not capable of sustained high speed and high delivery rate operation. In many of the prior art devices the tubing creeps or abrades quite badly, and the devices are not adaptable to a wide range of tubing sizes and materials. many of the prior art devices also leave something to be desired as the flow is often highly pulsatle in character and the devices are subject to some backow during a portion of each pumping cycle. A number of the prior art devices are quite complicated mechanically and are thus prone to many minor defects which require an overabundance of maintenance and repair work.

The p-resent invention provides a tubing pump capable of continuous high speed and high delivery rate operation in which a piece `of flexible tubing is placed between a rubber or other compression plate and a `gyrating cone which is driven by an eccentric cam. As the eccentric cam rotates different portions of the periphery of the cone are raised to compress the tubing progressively between the cone and the resilient compression plate. The liquid which is being pumped is forced along the tubing ahead of the portion of the tubing which is occluded by the action of the cone and the compression plate, and behind such portion a vacuum is left which causes fresh liquid to be forced into the tubing. The tubing is arranged in spiral form extending over an arc of more than 360 so that a portion of the tub-ing overlaps the inlet. The `overlapping of the tubing prevents backflow and provides a substantial even flow without appreciable pul- 'sations. The cone of the present invention is restrained against rotation and different portions of the periphery thereof are raised successively to compress the tubing, therefore the creeping or abrading of the tubing is elim- The llow characteristics of i inated. The rubber compression plate also allows the ice when the pump is operated at very high speeds and pressures.

An object of the present invention is the provision of a tubing pump for pumping blood and other sterile liquids.

Another object is to provide a tubing pump for pumping radioactive or corrosive liquids and gases.

A further object of the invention is the provision of a tubing pump capable of sustained high speed and high delivery rate operation.

Still another object of the invention is to provide a high speed tubing pump which is mechanically simple and has a minimum of moving parts.

A further object of the invention is the provision of a tubing pump in which the discharge flow is relatively free of pulsations and in which backllow is eliminated.

Another object of the invention is the provision of a tubing pump in Which the drive mechanism and bearings are protected from contamination in the event of a rupture of the tubing carrying the fluid.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawing in which like reference numerals designate like parts throughout the figures thereof and wherein:

Figure 1 shows a plan View of a preferred embodiment of the invention, with a portion of the base plate cut away.

Figure 2 shows a section of the device taken along line 2 2 of Figure 1 looking in the direction of the arrows.

Figure 3 shows an elevational view of the device with a portion of the casing cut away.

Referring now to the drawings, wherein like reference characters designate like or corresponding parts throughout the several views, there is shown in Figs. 1 3 (which illustrate a preferred embodiment) a tubing pump generally designated by the numeral 11 comprising a casing 12 which has an axial bore 13 therethrough adapted to receive a drive shaft 14, which may be driven by any suitable source of power such as a variable speed electric motor, not shown.

A beveled cylinder 15 is coaxially mounted upon the drive shaft 14, said beveled cylinder carries an eccentric cam shaft 16, the axis of which is offset and forms an angle with the axis of the drive shaft 14. The drive shaft 14 is mounted in the casing 12 by means of a roller bearing which has an outside race 17 securely fixed in the casing 12, an inside race 18 fixed to the drive shaft 14 and rollers 21 between the two races.

The inside race 22 of another roller bearing assembly is pressed over the cam shaft 16 and abuts the beveled surface of the beveled cylinder 15; the -outer race 23 of said bearing assembly which has rollers 29 positioned between the two races carries a cone shaped element 24 having a depending circular flange 25 on its under surface into which the outer race 23 of the roller bearing assembly fits. In the upper side of the conical element a circular groove 26 is cut which has an arcuate outer face 27 adapted to receive a complementary crowned ring 28 which depends from a base or cover plate 31. The upper side of the conical surpace also has a semi-spherical socket 33 adapted to receive a ball bearing 34. As previously pointed out, a base plate 31 is provided to fit over the open end of the casing 12 and is affixed thereto by any suitable means, for example, a stud 35, with a stud pin 36 passing therethrough to prevent its rotation, mounted in the casing 12 and a locking nut 37 adapted to coact with the threaded portion of the stud 35. The base plate 31 may be provided with a depending flange 32 at its periphery as shown in Figs. 2 and 3. The base plate 31 also has a semi-spherical socket 38 cut into its under side to receive the ball bearing 34. These' .'-sph'erical socket 33 in the upper surface of the cone is somewhat less than half a sphere so that the cone 24`will be capable of gyratingrabout the -ballbearing 34. Referring now to Figure 2, there is shown a Yresilient compression plate 41, prefer ably formed of rubber, but which may be constructed of any suitable resilient material affixed to the base plate 31 and positioned between the dependingcrowned ring 28 and the outer depending flange 32 of said base plate; Positioned between the cone 24 and the resilient compression plate 41 is a flexible tubing 42 made of any suitable material such as rubber or plastic, said flexible tubing enters the pump by means of port 43fin the base plate 31 and leaves the pump byarneans of a similar port 44.

Tubing access slots

45 and 46 are provided inthe base plate 31 to permit exible'tubing 42 to be readily removed and replaced;A As can best be seen by references to Figure l this flexible tubing circumscribes anV arc of more than 360; this arrangement ensures delivery over an entire cycle, except for a small angle of rotation as Ythe sector of occlusion passes over the outlet port, and it also prevents momentary backflow. Y

It can be seen by reference to Figures 2 and 3 that the inner face 47 of the wall of the casing 12 is of arcuate configuration, the curvature of said arc being determined by the path of the periphery of the cone 24 as it gyrates. The outer surface 48 of the cone 24 is properly machined to t the configuration of the inner face 47` so` that the clearance between this outer surface and the ginner face of the casing wall is kept lat a minimum. The flexible tubing 42 is very tightly Vconfined between the cone 24 and the compression plate 41 and because of the close fit between the

complementary surfaces

27 and 28 and l the

surfaces

47 and 48 the tubing cannot rupture due to high pressures and it cannot become pinched or abraded. This enables the pump to be operated at extremely high pressures.

A resilient sleeve 51, made of a suitable material such as -rubber or neoprene isA affixed to an inner portion of the casing 12 by means of a metal retaining ring S2. This is a very important feature of the invention 4as it prevents the liquid from contaminating the bearings in the event the flexible tubing 42 should rupture. In this regard a drain hole `53 Ais provided in the bottom of the casing 12 so that the liquid may be drainedl from the pumpin event such rupture does occur. `Referring now to Figure 2 it can 'be seen that the axis of the drive shaft 14 and the axis of the cam shaft 16 intersect at the center of the ball bearing 34A and that the angle between the two axes is the same as the greatest angle between the compression yplate 41 and the plane of the conical surface 24. Thecenter ofthe ball bearing 34 is thus the center of gyration for the cone 24. The radius of curvature of the compressing face of the cone 24 is made suiciently large so that the flexible tubing is occluded over an appreciable sector, and thus the tube is sealed against backflow at any angular positionof the drive shaft.

In operation, the drive shaft 14 is rotated by a suitable source of power, which in turn rotates eccentric cam shaft 16 and the motion is transmitted to the coneV 24 by means of the roller bearing located between the cam The cone then gyrates about the f l shaft Vandsaid cone. center of the ball bearing 34. The friction between the cone 24 andthe tubing -42 and the rotational friction between the ball bearing 34 andthe cone 24 is greater than the friction in the roller bearing between the cam shaft `16 and the cone thus the cone is restrained against rotation. As the cone'24V gyra'tes diiferent points on the periphery thereof are raised to compress the tubing 42 progressively between. the cone and theV resilientcompression plate 41. The liquid which is being pumped is forced along the tubing ahead of the portion which is occluded by the action of the-cone and the compression plate and behind such occluded portion a vacuum is left which permits `fresh liquid to be forced into the tubing. By reference to Fig. 2 it can readily be ascertained that any given point on the cone 24 oscillates about the center of gyration of the conc-center of ball bearing 34-moving toward and away from an opposed point on the resilient compression plate `41. As the gyration proceeds a rolling action is produced which compresses and expands the tube progressively along its length and advances the iluid through the tube.

By selecting a rubber or other resilient material of suitable composition for the compression plate 41 and mak ing it of the proper thickness a wide range of tubing wall thicknesses can be accommodated without changing the ring. It has been found that a rubber of medium texture is best for general overall use. The maximum delivery rate of the pump can be effectively regulated by using compositions of different resiliencies. If a composition of low resiliency is used muchl higher delivery pressure and hence greater ows can be obtained than i-f a highly resilient composition were used. For example, if a highly resilient material such as sponge rubber isiused, the maximum delivery pressure may be on the order of only l0 p.s.i., whereas, if a very hard rubber composition is used maximum delivery pressures in the neighborhood of 40 p.s.i. are obtainable.

It should be pointed out'that this pump is very satisfactory for the pumping of human blood as the amount of hemolysis is sufliciently low to meet medical standards; in fact, in tests run by .the inventor, the amount of hemolysis was considerably lower than had previously been recorded for known pumps. It yis thought that the elimination of back flow, the use of tubing of large internal diameter and having a large radius of curvature when installed in the pump, plus the substantial elimination of pulsatile ow contributes substantially to the in hemolysis. l

It should be understood, of course, that the foregoing disclosure relates to only a preferred embodiment of the invention and that it is intended to cover all changes and modifications of the example of the invention herein chosen for the purposes of the disclosure, whichdo not constitute departures from the spirit and scope of the invention set, forth in the appended claims. What is claimed is:

1. In a tubing pump, a casing, a member having a conical face mounted for gyratory movement within said casing, driving means for said member, a cover plate having a resilient face covering said casing, bearing means comprising a single ball positioned in sockets formed in said member mounted for gyratory movement and said cover plate, the center of said bearing means being coincident with the center of gyration of said member mounted for gyratory movement, and a flexible tubing having an over# reduction Y lapped loop formed between inlet and outlet portions thereof, said loops being positioned between the resilient face of said cover plate and the conical face of said member mounted for gyratory movement. 5

2. In a tubing pump, a casing, a member mounted for y gyratory movement within said casing, a cover plate covering vsaid casing, bearing means comprising a single ball mounted in sockets in said member mounted for gyratory movement and said cover plate, the center of said bearing means being coincident with the center of gyration of said member mounted for gyratory movement, resilient means positioned between said cover plate and said member mounted for gyratory movement and a exible 'tubing having a loop `formed between inlet and outlet portions thereof, the loop being positioned between said resilient meansV and saidmember mounted for gyratory movement.

3. In a tubing pump, a casing, a member mounted for gyratory` movement within said casing, a cover'plate covering said casing, drive means for said member passing through said casing, bearing means located between said casing and said drivemeans and `between said drive means and saidmember mounted for` gyratory movement, a exible tubing having a loop between inlet and outlet portions thereof, the loop being positioned between said cover plate and said member mounted for gyratory movement, and a flexible sleeve surrounding said bearing means and positioned within the casing in sealing engagement with said member and said casing to shield said bearing means from the contents of said flexible tubing should said flexible tubing rupture.

4. In a tubing pump, a casing having an open end, a member having a conical surface positioned within said casing, means for imparting a gyratory motion to said member including bearings positioned between said casing and said member, a cover plate covering said casing, bearing means comprising a single ball and sockets therefor in said member having a conical surface and said cover plate, the center of said bearing means being coincident with the center of gyration of said member, resilient means positioned between said cover plate and said member having a conical surface, a flexible tubing having a loop betweeninlet and outlet portions thereof and positioned between said resilient means and said member having a conical surface, and ilexible means surrounding the bearings which are included in the gyratory means, to protect said bearings from contamination in event of a rupture of said iiexible tubing.

5. In a tubing pump, a casing, a drive shaft mounted in said casing, bearing means interposed between said casing and said drive shaft, an eccentric shaft extending from said drive shaft in said casing and offset at the juncture thereof with said drive shaft, the upper end of said eccentric shaft extending angularly toward and above the axis of rotation of said drive shaft, a gyratory member having a conical surface and mounted for non-rotating gyratory motion on said eccentric shaft, bearing means interposed between the eccentric shaft and the gyratory member, a cover plate mounted on said casing, a single ball set in said cover plate `and in said gyratory member and aligned with said axis of rotation for firmly supporting said gyratory member, and a length of flexible tube having a looped portion interposed between said cover plate and the conical surface of said gyratory member whereby the looped portion of said tube is progressively compressed and released, the ends of said tube extending exteriorly of said casing and through said cover plate.

References Cited in the le of this patent UNITED STATES PATENTS 1,848,024 lOwen Mar. l, 1932 2,249,806 Bogoslowsky July 22, 1941 2,534,855 Corneil Dec. 19, 1950 2,752,852 `Oiutt July 3, 1956 FOREIGN PATENTS 7,844 Great Britain of 1938