CA1214073A - Hose pump for medical uses - Google Patents

Abstract

Abstract of the Disclosure A hose pump comprises a housing in which a drive shaft is mounted. The shaft is provided with an obliquely extending shaft piece on which a swash plate is mounted. The swash plate end face presses against a hose which lies in an annular groove located in the underside of the housing cover.
The swash plate does not substantially rotate relative to the housing or to the hose and therefore exerts substantially no shear on the hose.

Description

~lZ14073 HOSE P~MP FOR MEDICAL USES
_ ._ Field of InYe1ltion .. . .
This invention re1ates to a hose pump. More particularly, this invention relates to a hose pump for medical uses.

Back~round of the Invention s The supplying of liquids into the body of medical patients is effected in many instances from a ~upply vessel from which the liquid runs out by the influence of gravity.
If a higher precision in the rate at which liquid is supplied is required, or if the delivery pressure from gravity is not l o sufficient, positive-displacement pumps are used. The structural parts of such pumps which co~e in contact with the liquids are, as a rule, made of plastic articles intended for a single use and which are discarded after such use. These plastic articles should be easy and inexpensive to manufacture. In addition, t;hey should ensure the medically necessary precision and safety.

18 U.S. Patent No. 2y915~983 discloses a hose pump wherein a drive shaft is monnted in a housing. The drive lg shaft has at its end an eccentrially arranged shaft piece ; extending at an angle. On this shaft piece, a swash plate is mounted which is secured against rotation relative to the housing of the hose pump. 13etween the swash plate and a cover which closes the housing, a hose section laid in rings is arranged. The ends of the hose section are passed thro11gh " slots in the cover. The hose ends are brougllt out Or the cover and are connected with a liquid source and with a user~

When the drive shaft rotatei, the swash plate is callsed to 29 wobble, pressing a region o;i` the annular hose section against the cover and squeezing it `lat. The flattened re~ion moves during the wobble motion, '30 that the liquid contained in the annular hose section is pushed forward in the hose.

Hose pumps of` thu prior art have the disadvantage that insertion of the hose is difficult and requires a certain s~ill. A section of the hose must be laid in the coYer or respectively over the swasn plate in rings? while the very long ends are brought out sf openings in the cover. The diameter of the annular hose section is not fixed~ so that the position of the annular hose section in the hose pump is undefined. If the diameter of this annular hose section is made too large or too small, relative movements between the annular hose section on the one hand and the cover or swash plate on the other hand will occur during the revolving squeezing by the swash plate. These relative movements lead to increased friction and to wear and loss of output. In addition with the hose pumps of the prior art, the insertion of the hose requires a cer~ain degree of experience. If the hose is inserted the wrong way, the pump will deliver in the wrong direction.

Also known, ls a hose pump (U.S. Patent No.

3,720,489) where a swash plate forms the cover of the housing.

22 The annular hose section is installed in an annular groove in ~ the llousing. The swash plate is pressed in the direction of the annular groove by a spring. In this ilose pump also, the ~ hose may be inserted to ary direction with the possibility of connecting the long hose ends protruding from the housing in any manner. This hose pump also does not provide for simple changing of the hose and (loes not ensure that the hose can be 28 , inserted only in a defined position in order to avoid ùnintenJed reversal of the delivering direction.

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~2~0~73 For medical uses, where the hose pu~p is to deliver, for example, blood or a ser~lm, the hose is used as a disposable or throw-away ar~icle. Therefore, it must be easy to remove the hose from the pump and to replace it. Since incorrect insertion of the hose may, in such applications, have serious consequences for the patient, it must be assured that operation of the hose pump is possible only with the hose inserted correctly.

Ob~ect of the Invention It is therefore an object of the present invention to provide a hose pump, particularly for medical uses, where the hose can be replaced in a simple manner and which can be handled without problems, for instance, by the nursing personnel of a hospital or the patient.

These and other objects of the present invention will become apparent from the following description and claims in conjunction with the drawings.

Summary of the Invention In accordance with the present invention, the cover of the hose pump has on its underside an annular groove for securing the annular hose section as well as a clamping means for fixing the hose in the cover. The hose ends are connected with a co~mon coupling piece which is insertable in the cover and has inflow and outflow connections. On the side Or the cover opposite the couplin~; piece, t~le cover is conl)ect.e~i with 25`
the housing by a hinge. A locl;ing device is arra~lgt?~i ncal t.ht?

coupling piece for lockin~ the cover in tht? clcsed positio the housing.

Brief Description of the Drawings In the drawin~s formin~ part hereof:

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~2~4~7a Fig. 1 is a longi~udinal sectional view through a hose pump in accordance witll one embodiment of the present invention;
Fig. 2 is a view alon~ line II-II of Fig. l;
Fig. 2a is a sche~natic view of a modified embodiment of the invention as illustrated in Fig. 2;

Fig. 3 is a partial schematic front view of the hose pump of the invention from the direction of arrow III in Fig.

. l;
Fig. 4 is a schematic longitudinal sectional view l o through the working part of a double hose pump in accordance with another embodiment of the present invention; and, 13 Fig. 5 is a schematic view of the cover of the double hose pump illustrated in Fig. 4 in the open state with the hoses inserted.

Description of the Preferred Embodiments In order to provide a more complete understanding of the present invention and all appreciation of its advantages, a description of the preferred embodiments is presented below.

In the hose pump according to the invention, and with reference to Fig. 1 and Fig. 2, both ends of the hose 26 are connected with a common coupling piece 29 which is inserted together with the hose 26 in a recess or annular i groove 31 in the cover 22 of the hose pump. Thus the hcse 26 , together with the coupling piece 29 forms a throw-away unit.
25~
; The coupling piece 29 assures that the hose 26 is inserted in the cover 22 in the correct position and direction of delivery. Changing the ho~e 26 is done after the cover 22 has been flapped up about the hinge 31~. Chan6in~ the l~ose 6 mere~y requires simple manipulations. A lockin~ device 37 is

-4-., ~214073 released and the cover 22 flapped up. Then the hose 26, together with the coupling piece 29, is removed from the cover 22 and replaced by a new ho~e and coupling piece. The annular groove 31 brings about the exact positioning of the annular hose section 26 in the covel 22, so that no major displacements of the hose 2li ocour in operation. In particular, frictional stress in the circumferential direction of the hose is avoided. In;ertion of the hose is facilitated by the pivotable mounting arrangement of the cover on the housing. The cover 22 is captive and is guided exactly during the closing movement. Therefore, shifting of the hose and wedging of the hose durlng losing of the cover is avoided.

In hose pumps~ the danger exists that delivery may stop briefly, so that even a drawing back of the liquid occurs if the squeezing element passes over the outlet-side end of the hose and this end does not subsequently regain the full hose cross-section~ To avoid or at least to reduce the discontinuities caused during the delivery, in accordance with the present invention, two hoses may be arranged side by side in a plane with each hose 26 having its own swash plate 20 assigned to it. (See Figs. 4 and 5). The swash plates 20 are driven by a com~on drive at equal speeds, and the two hoses share a common coupllng pi~ce 29 having a sin~le inflow and a single outflow. In this way, two hose pumps are combined in such a manner that their hc~ses to~ether with the couplin~
piece form a sin~le throw-c;way or disposable unit. The two hoses may be arranged in a common cover~ The swash plates 20 of the two hoses are driven phase-shifted or in phase opposition, so that the critical phases of the brief inierruption of the delivery ~o not coincide.

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~14073 In the following the illustrative embodiments of ¦ the invention are explained .~n greater detail with reference to the drawings.
~' The hose pump illustrateà in Figures 1 to 3 j comprises a housing 10 with a cylindrical bore 11 in which a sleeve 12 is mounted for lengthwise displacement. In the interior of sleeve 12, ball bearings 13 support the shaft 14, l which is driven by an electric motor 15 through a reduction 8,j gear 16. The drive shaft 17 -~s formed by the output shaft of the reduction gear 16, and i~ is coupled with shaft 14 via a fork type coupling 18 in sucl1 a way tl1at shaft 14 can execute small axial displacements reLative to the output shaft 17.
i At its output end, shaft 14 has an angularly bent l3' shaft piece 18, the axis of which forms with the axis of shaft 1' 14 an acute angle alpha ("~"). The swash plate 20 is mounted 15 :' on this shaft piece 18 through a ball bearing 19. Ball 16il bearing 19 and swash plate ~0 are contained in a chamber 21 inside the housing 10. This chamber can be closed with the ~I cover 22. In the present e~lbodiment, the swash plate 20 19 ~ .
comprises a ring, the outer end face 23 of which is beveled to 20l ! match the angle alpha. The intersection of the axes of shaft I 14 and shaft piece 18 lies in the plane of the mean dia~eter 22j ,i "b" of the end face 23 (i.e. of the diameter of the median ¦I circle of the conical surface of the end face 23).

24~1 The ball bearing 9 is n~ounted in the interior of ¦l the ring, the outer end fac of which is sealed ~y a seal disk 27l 24, so that no liquid can p;l-etrate through the a~ial channel ¦1 of the swash plate 20. The inner edge of a ~e~nbrane 25 is fastened at the circumf~rence of the swash plate 20. T~e 30i outer ed~e Or membrane 25 lS fastened on the sidewall of lZ14073 ~!
` chamber 21 of housing 10~ ~hus the seal disk 24 together with the membrane 25 forms a liquid-proo~ seal between the drive ~echanism of swash plate 20 against the sp~ce receiving the hose 26.
Hose 26 is attached to the underside of cover 22.
With reference to Fi~. 2 hcse 26 is bent or curved in the

6`l form of a ring with the inlet 27 and the outlet 28 being ! arranged side by side and extending out radially with respect !j~ to the ring. Inlet 27 and outlet 28 are connected with a coupling piece 2~ of essentially L-shaped or angle form whose 10 "
inflow nipple 30 and outflow nipple 30 protrude from the cover 22 vertically.

Hose 26 is inserted in an annular ~roove 31 on the underside of cover 22. This annular groove 31 is limited j internally by an axially raised projection 32 and externally by a circlin~ edge 33 of eqlal depth. As can be seen from 16 ',!
Fig. 1 the annular swash p~ate 20 engages into the annular I; groove 31 of cover 22. The depth of penetration of swash 8 !, 1 plate 20 into groove 31 varies over the circumference because 19 ' of the oblique position of swash plate 20. Hose 26 is ; squeezed together in the axial direction between the outer face 23 of the swash plate 20 and the bottom of the annular 22ii groove 31.
23 ;
ll With referel1ce to Fig. 1~ the Inean diameter a" of ¦¦ the annular end face 23 of swash plate 0 is the same as the ¦I mean diameter b of the annulal groove 31 ~hich in turn is 26l;
the mean diameter of the hose ring inst.alled in sroove 31. ~s 27 j a result the end face 23 executes a pure rollin~ moven1ent in il ~roove 31 but without turr!ing in this ~roove. If the mtan li di~eters a and b are dit`ferent the ~wash platæ ~n would

-7-~2~407a tend to revolve slowly in the housing about the shaft piece 18. In so doing it would e~ert a shearing action on the hose 26, and this would cause friction losses which reduce the efficiency.
Cover 22 is fastened to housing 10 by a hinge 34, so that it can be flapped or pivoted open according to Fig. 2.

The coupling piece 29 is located at the end of cover 22 opposite to the hinge 34. ~t this end an oblong slot 35 is provided. The hose 26, inserted in cover 22 from below, is retained by fishplates 36 which partly span the inlet-side end 1 o and the outlet-side end of hose 26. Between these fishplates 36, however, there is a gap which is wide enough for the hose 26 to be taken out of cover 22 with relatively slight deformation.

The embodiment of the invention illustrated in Fig.

2a corresponds to a large extent to that of Fig. 2. The only difference is that instead of the fishplates 36, which according to Fig. 2 retain the hose 26 in the cover, there is provided at the edge of the oblong slot 35 in cover 22 a semi-cylindrical bulge 36 t which presses one hose end near the coupling piece 29 in the direction of the other hose end. The hose is thus deformed, both hose ends being slightly compressed and retained in cover 22 by clamping type action.

I To lock the cover 22 in the closed position in the 24 i housing 10, claws 37 are provided at the end of cover 22 i opposite to hinge 34. Thece claws 37 are n~ounted by a hinge pin 38 on cover 22 and are pressed into the locking po~ition by a spring 39. As illustrated in Fie. 2 and Fig. 3, their outer ends 40 engage in lateral recesses in housing 10 to lock cover 22 to housing 10 in the closed position. By laterally

-8-12~40~3 pressing in the claws 37, their ends 40 are spread apart witl the springs 39 being compr~ssed. The cover 22 is thereby unlocked from the housing 10 and can be lifted up.

To place the hose pump into use, first hose 26 together with the coupling piece 29 is inserted in cover 22 in the manner shown in Fig, 2. Then, cover 22 is closed and locked on housing 10. As a result, the swash plate 20 is pressed against hose 26 in its farthest protruding region so fir~ly that it pinches the hose 26 in the annular groove 31.

A single nip forms along the circumference of the ring formed by hose 26. This nip is sufficiently long in the circumferential direction that no short circuit develops at the inlet and outlet. Briefly, both hose ends 27 and 28 are pinched jointly. When motor 15 is turned on, shaft 14 rotates and swash plate 20 executes a wobble motion, but without participating in the rotation. Due to the wobble motion, the point at which maximum compression of hose 26 takes place circles along the ring formed by hose 26 at constant speed.

In this way, the liquid contained in hose 26 is pushed forward from the inlet 27 to the outlet 28.
After use, the claws 37 are released and cover 22 flapped up. The hose 26 together with the coupling piece 29 can then be removed and replaced.

!` The ball bearings 13 and 19 for supporting shaft 14 24' I and swash plate 20 respèctively not only serve as radial ball bearings but are also able to transmit axla~ forces~

27 Accordingly, the bearing pressure of spring 41 is transmitted to swash plate 20. Spring 41 is supported on the rear end wall of housing 10 and pres~es against a ring shoulder 42 of sleeve 12, so t.hat sleeve 12 to~ether with shaft 11~ and the 1~ 07;~
ball bearings 13 and 19 as well as the swash plate 20 are pressed in the direction of hose 26 or cover 22 by the force of compressed spring 41. In order to secure sleeve 12 non-rotationally in housing 10, a radially projecting pin 43 extends through an axial slot 44 in the wall of housing 10 and into a bore provided in sleeve 12. Pin 43 serves also as axial stop, so that the swash plate 30 will not fall out of the !; housing 10 when the cover is open. In addition, when the cover is closed without a hose placed in groove 31, pin 43 prevents swash plate 20 fro~ coming in contact with the guides 32 and 33 and causing damage.

Since that part of the swash plate 20 which projects axially farthest forward anl causes the maximum pinching of the hose 26 revolves on the circle formed by the hose, liquid is transported from the inlet 27 to the outlet 28.
In the embodirnent illustrated in Figs. 4 and 5, two hose pumps are arranged side by side in a common housing 10.

The swash plates 20 of both hose pumps are driven in opposite directions and their inlets 27 are connected with one another, as are also their outlets 2~. Preferably, both swash plates are driven each at the same speed most suitably by a common drive mechanism (not illustrated). The inlets 27 are connected with an inflow 30 of the couplin~ piece 29. The outlets 28 are connected with ~n outflow (not shown) of the ~ coupling piece 29. Referrin~ to Fig. 5, couplin~ piece 29 is arranged in a gap 45 ln the cover 22 which i.S ope1l on the side of cover 22 opposite to the side where the hi1l~e 34 is located.

As is evident from Fig. 4, the two swash plates 20 have a relative phase shift of 1~0. While the left swas}

~21407;~
plate 20 executes the strongest pinching of the respective hose 26 on the side adjacent to the coupling piece 29, the ri~ht swash plate 20 causes maximum pinching at the same moment at the point of the respective hose 26 farthest away from or remote from the coupling piece 29.
In the embodiment of the invention illustrated in Figs. 4 and 5, the cover 22 receives the two hoses 25, which jointly lie in a common plclne. Together with the coupling piece 29 arranged between them, the hoses 26 form a disposable unit. Because of the phas~shifted drive of the two swash l o plates 20, any discontinuities in time of the total delivery of the hose pump are diminished.

13 It will be readi:'y appreciated that the details of construction of the right and left swash plates 20 and associated mechanisms of the embodiment of Fig. 4 may be suitably substantially sim:,lar to the details illustrated and described in conjunction w:~th the embodiment of Fig. 1.

Although preferrl?d embodiments of the present invention have been descrihed in detail, it is contemplated that modifications may be made within the spirit and the scope 2~
of the invention.

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Claims (9)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A hose pump for medical uses comprising:
a housing having a first section and an adjacent second section;
a first drive shaft mounted in said housing first section, a first shaft piece joined to and extending obliquely away from said first drive shaft, a first swash plate mounted on said first shaft piece, means for substantially non-rotationally retaining said first swash plate relative to said housing;
a second drive shaft mounted in said housing second section, a second shaft piece joined to and extending obliquely away from said second drive shaft, a second swash plate mounted on said second shaft piece, means for substantially non-rotationally retaining said second swash plate relative to said housing;
wherein said first and second swash plates are arranged side by side;
a cover mounted on said housing having an underside facing said first and second swash plate with said cover in the closed position, wherein said cover underside facing said first and second swash plate substantially lies in a common plane; and drive means for driving said first and second swash plates at equal speeds.

2 A hose pump as recited in claim 1 further including:

a first annular hose section having an inlet and an outlet pressed between said first swash plate and the underside of said cover with said cover in the closed position;
a second annular hose section having an inlet and an outlet pressed between said second swash plate and the underside of said cover with said cover in the closed position;
wherein said first and second hose sections substantially lie in a common plane; and a common hose coupling piece connected in fluid communication with the inlet and outlet of said first hose section and the inlet and outlet of said second hose section wherein said common hose coupling piece has a single inflow and a single outflow.

3. A hose pump as recited in claim 1 wherein said cover is hingedly mounted to said housing.

4. A hose pump as recited in claim 1 wherein the underside of said cover has a first annular groove for receiving a first annular hose section and a second annular groove for receiving a second annular hose section:
said first swash plate is a ring-like member having a top face protruding into said first annular groove with said cover in the closed position;
said second swash plate is a ring-like member having a top face protruding into said second annular groove with said cover in the closed position.

5. A hose pump as recited in claim 1 wherein the plane of the top face of said first swash plate is arranged with respect to the plane of the top face of said second swash plate whereby, upon rotation of said first and second drive shafts by said drive means, said first and second swash plates are driven in phase opposition.

6. A hose pump as recited in claim 2 wherein the plane of the top face of said first swash plate is arranged with respect to the plane of the top face of said second swash plate whereby, upon rotation of said first and second drive shafts by said drive means, said first and second swash plates are driven in phase opposition.

7. A hose pump as recited in claim 4 wherein the plane of the mean diameter of said first swash plate top face is approximately parallel to the plane of the mean diameter of said second swash plate top face whereby, upon rotation of said first and second drive shafts by said drive means, said first and second swash plates are driven in phase opposition.

8. A hose pump as recited in claim 4 further including:
a first annular hose section having an inlet and outlet disposed in said first annular groove and pressed between said first swash plate top face and said underside of said cover with said cover in the closed position;
a second annular hose section having an inlet and outlet disposed in said second annular groove and pressed between said second swash plate top face and said underside of said cover with said cover in the closed position; and a common hose coupling piece connected in fluid communication with the inlet and outlet of said first hose section and with the inlet and outlet of said second hose section wherein said common hose coupling piece has a single inflow and a single outflow.

9. A hose pump as recited in claim 7 further including:
a first annular hose section having an inlet and outlet disposed in said first annular groove and pressed between said first swash plate top face and said underside of said cover with said cover in the closed position;
a second annular hose section having an inlet and outlet disposed in said second annular groove and pressed between said second swash plate top face and said underside of said cover with said cover in the closed position; and a common hose coupling piece connected in fluid communication with the inlet and outlet of said first hose section and to the inlet and outlet of said second hose section wherein said common hose coupling piece has a single inflow and a single outflow.