IE46878B1

IE46878B1 - A valve for adjusting the flow of a liquid under gravity

Info

Publication number: IE46878B1
Application number: IE915/78A
Authority: IE
Inventors: Yoram Palti
Original assignee: Yarden Medical Eng Ltd
Priority date: 1977-05-06
Filing date: 1978-05-05
Publication date: 1983-10-19
Also published as: LU79602A1; NL8801639A; DE2720522A1; GB1554629A; SE442923B; SE7805076L; IT7849207A0; NL183984C; DK154867C; DE2720522B2; DK154867B; DK196678A; ES469514A1; FR2389934A1; IT1102845B; DE2720522C3; CH633376A5; FR2389934B1; ATA324778A; IE780915L

Abstract

In a housing (12) a float chamber (72) is provided in which a float (18) is arranged in a freely movable manner, whose external diameter is smaller than the internal diameter of the float chamber (72) so that liquid can flow downwards unhindered along the outer wall of the float (18). At its upper end the float (18) has a valve stem (20) for closing an inlet port (14) of the housing (12) and at its lower end it has a spherical attachment (28) for closing a connection duct (32) adjacent to which there is an outlet port (16) of the housing (12) which can be closed by a manually actuable valve stem (56). The float (18) has an approximately oval longitudinal section and a tip which is directed upwards. As a result it is possible to achieve, e.g. in the case of infusions, unhindered uniform outflow of liquid along the curved float wall, if this drips from the inlet port (14) onto the float (18).

Description

This invention relates to an apparatus for controlling the flow of a liquid under gravity from a liquid container to a consumer, for example in connection with devices for the intravenous infusion of a liquid, the apparatus comprising a housing defining a float chamber with an inlet and an outlet opening, a float movable within the float chamber, a valve shaft on the upper end of the float for closing the inlet Opening when the liquid within the float chamber reaches a predetermined level and a manually operable valve member for adjusting the cross-section of the outlet opening.

In a known appliance of the above mentioned type, the float is cylindrical, so that the liquid, usually entering only dropwise through the inlet opening, gathers on the upper, substantially horizontal face of the float and does not flow freely down from the latter to the outlet opening. With infusions, however, for which this appliance is used mainly, it is essential that the flow of the solution flowing through the apparatus, which is passed into the vein of a patient, is homogeneous and remains unhampered.

According to the invention, there is provided an apparatus for adjusting the flow of a liquid under gravity comprising a housing defining a float chamber having an inlet and an outlet, a float having a valve shaft at its upper end, the body of said float being the surface of 6878 revolution of a convex curve about the longitudinal axis of the body, the upper end of said body tapering towards said valve shaft, said valve shaft having a valve surface defined thereog which serves chamber in operation for closing the inlet opening when the liquid in the float/has reached a predetermined level and a manually operable valve for adjusting the cross-section of the outlet opening.

The float is preferably substantially egg-shaped. The shape of the float allows for an undisturbed and unhampered homogeneous flow of the liquid descending from the inlet opening onto the float or flowing down along the curved wall of the float.

The angle between the longitudinal axis of the float and the tangent to its upper end, that is the angle between the wail of float and the valve-shaft, is preferably approximately 45°.

The lower end of the float is preferably provided with substantially hemi-spherical head made of a flexible material for sealing a channel leading from the float chamber to the outlet opening, the entrance to the channel being similarly hemi-spherically rounded.

On the lower end of the head . there may be provided for example, an arrow-shaped guiding-pin, extending more or less deeply into the connecting channel, according to the position of the float.

The valve surface is preferably conical and cooperates with a conical seat surrounding the inlet opening, in order to open or to close the inlet opening, a cylindrical guiding-pin being provided on the valve surface, which extends axially through the inlet opening, a clearance being provided between the guiding-pin and the inlet opening. By means of the two guiding-pins the float is kept in use in an approximately vertical position, only slight deviations from the latter being possible, the deviations being due to the clearance between the guiding-pins and the holes through which they extend.

In a further embodiment of the invention, the housing is provided with a frusto-conical lid having air vent apertures and a filter is arranged between the lid and the housing, in particular a hydrophobic filter, that may have the form of a funnel and may consist of silicon-impregnated filter paper, for example. In order to attach and hold the filter in a simple manner, the housing may be provided with annular grooves and the lid with corresponding annular ribs, the ribs may be locked into the grooves with a snap action in such a way that the filter paper is held between the ribs and grooves. Alternatively, the grooves may be provided on the lid and the ribs on the housing, or a combination of the two arrangements may be used. In this way the lid may be attached to the housing in a quick and simple way and the filter may be held tightly and securely simultaneously.

The manually operable valve is advantageously provided with a conical or frusto-conical valve member having a small angle of taper, allowing for a sensitive adjustment of the cross-section of the outlet opening. The valve may be provided with a thumb-wheel on which a suitable graduation may be applied, the valve being kept within the adjusted loaded position by means of a^spring under tension, the spring being arranged between the housing and the head of the valve shaft.

An exemplary embodiment of the invention is illustrated in detail in the accompanying drawings, in which:Figure 1 is a section through a preferred embodiment of the apparatus according to the invention; and Figure 2 shows a detail of the float of the apparatus shown in Figure 1.

An apparatus 10 for adjusting the flow of a liquid under gravity comprises a housing 12, having an inlet 14 at the top and an outlet opening 16 at the bottom. The housing is shown in Figure 1 in the position for use.

In the housing there is arranged within a float chamber 72 a freely movable float 18, the external diameter of which is sufficiently smaller than the internal diameter of the float chamber to enable an unhampered and undisturbed flowing down of the liquid on the external wall of the float 18. In each case the largest external diameter of the float 18 is sufficiently smaller than the interior diameter of the float chamber 72 to avoid the occurrence of capillary forces between float and float chamber. On the internal wall of the float chamber 72, there are formed at suitable intervals longitudinal guiding ribs 34, centering and guiding the float 18 within the float chamber, in case this should be desired or required.

As shown, the float 18 has in vertical cross-section approximately the form of an egg, the point of which is directed upwards. On the upper end of the float 18 a valve-shaft 20 is provided of a generally cylindrical form, which advantageously consists of one piece together with the float 18. The valve-shaft 20 is equipped with a conical valve surface 22, the latter acting together with a correspondingly conical valve seat around the inlet opening 14, in order to close or open the latter. The conical valve surface 22 is followed by a cylindrical, substantially needleshaped guiding pin 24 extending through the inlet opening 14, the external diameter of which is smaller than the smallest internal diameter of the, apart from the conical valve seat, essentially cylindrical inlet opening 14. The diameter of the guiding pin 24 may, for example, be up to 0.5 mm. It is kept as small as possible in order to keep the internal diameter of the inlet opening 14 as small as possible as well, which, in turn, will keep as small as possible the downwardly directed force exerted by the weight of the liquid upon the valve shaft. This is especially useful in case of difficult working conditions. However, the difference between the 6 8 7 8 internal diameter of the inlet opening 14 and external diameter of the guiding pin 24 is sufficiently large to avoid the occurrence of capillary forces between the inlet opening and the guiding pin.

Particularly in the range of the conical valve surface 22, the valve shaft is finely finished, for example, polished, and it seals the inlet opening 14 with a smallest possible force in the upward direction of the order of, for example, 1 gram.

The float and valve shaft may be made of a plastics material of slight elasticity.

The surface of float 18 is homogeneous and smooth, preferably water-repellant and the angle between the longitudinal axis of the float and the tangent at its upper end, i.e. at the passage from the egg-shaped wall of float 18 to the cylindrical wall of valve shaft 20 is preferably approximately 45°. Longitudinally of the float towards the wall of the casing the angle continuously decreases and reaches the value zero at the closest approach of the float to the casing, that is, at this point the tangent runs parallel to the longitudinal axis of the float and the casing.

The float 18 has at its lower end a nose or head 26 made of a flexible material, for example of latex-siliconrubber, which serves for closing tightly a connecting channel 32 leading from the float chamber 72 to the outlet opening 16. The head 26 may be formed directly on the float 18 or 6878 it may be, as shown, provided on a substantially spherical attachment 28 on the float 18, which itself may be formed directly on the float. The head 26 is formed in such a way that a smooth transition is provided from the curve of float 18 to the curve of head 26. Xt is secured, as mentioned, by the attachment 28, around which it partially grips, however, alternatively, it may be, for example, stuck to the float 18. The lower portion of the head 26 is substantially hemi-spherical and it acts together with a corresponding hemi-spherical portion of the casing 12 which surrounds the connecting channel 32 in order to close the latter tightly, even if the float 18 is not in the vertical position. The surface of the head 26 is - like that of the float 18 - smooth and homogeneous in order to allow for a homogeneous liquid flow and to avoid air bubbles adhering to their surfaces.

On the substantially spherical attachment 28 is provided an arrow-shaped guiding pin 30 which extends downwardly in such a way that It extends'with clearance into the connecting channel 32. By means of the guiding pin 30 the float, especially its lower part, is guided so that the connecting channel 32 is reliably sealed by the head 26, when the latter is sitting upon the corresponding depression in the casing 12 that surrounds the upper end of the connecting channel 32. The length of the guiding pin 30 is chosen so that in each position of the float 18 it will extend into the connecting 6 8 7 8 channel 32, so that a constant guiding of the float is achieved. The length of the guiding pin 24 on the valve shaft 20 is also chosen so that it always extends into the cylindrical part of the inlet opening 14. Thus, the float 18 is guided at both ends in a manner allowing for free flow of the liquid through the inlet opening 14 and through the connecting channel 32 in the corresponding positions of the float 18 without any hindrance.

As shown in Figure 2 the housing is equipped at the entrance to the connecting channel 32 with an annular valve seat 70, the interior diameter of which is sufficiently larger than the exterior diameter of the guiding pin 30, to avoid capillary forces between the channel and the guiding pin. However, the interior diameter of the channel is kept as small as possible in order to keep downwardly acting suction forces that could act upon the float, as low as possible. Then, if the buoyancy of the float is greater than its weight and if there are possible suction forces at its lower end, the float will lift from the upper opening of connecting channel 32, whereby due to the guiding of float 18 by the guiding pins shiftings or deformations are substantially avoided.

The arrow-shaped guiding pin 30 may be formed of one piece together with the float, as with the substantially spherical attachment 28. For example, when the float chamber is about three-quarters full, the sum of a possible suction force acting upon the float and its weight should be smaller than the buoyant force acting upon the float.

By means of the hemi-spherical seat on the housing 12 and the head 26 as well as by the flexibility of the latter a reliable and liquid tight sealing of the connecting channel is obtained, even if the float is not completely vertical or even if the head 26 is slightly deformed.

The housing 12 is provided with a frusto-conical lid 36, secured to the housing with a snap connection.

For this purpose, the lid has on its interior wall two annular ribs 40, 42 arranged at an interval from each other on the interior wall of the lid and spaced along the axis of symmetry of the lid. The housing 12 is equipped with corresponding grooves, into which the ribs 40, 42 lock, for example snap. Between housing 12 and lid 36, there is inserted a filter in the form of a membrane, which is frusto-conical. Preferably, the filter 38 is hydrophobic allowing for a venting of the float chamber to the exterior, impeding, however, the penetration of a liquid. The filter is gripped or otherwise retained between the grooves in housing 12 and the ribs 40, 44 around its entire circumference at the upper and lower ends thereof, so that a tight and sterile sealing of the filter chamber is obtained. The filter consists of flexible material, for example, silicon impregnated material or paper or a phase-separating filter paper, so that the filter chamber is vented through the 6 8 7 8 filter and corresponding air vent apertures 44 in the lid 36 without the liquid in the filter chamber, for example an infusion solution, in particular based on an aqueous solution, being able to penetrate to the exterior. Moreover, the filter reliably prevents the penetration of water or impurities from outside into the filter chamber. The large filter surface allows a low resistance for the penetration of air. The filter is sufficiently flexible so that it may be gripped between the grooves of housing 12 and the ribs 40, 42 of lid 36 without the danger of cracks or other damage occurring.

In housing 12, below connecting channel 32, there is arranged a manually actuable valve shaft 56, which is equipped with a conical nose or adjusting end 58 having a small cone angle, in order to be able to adjust the cross-section of outlet opening 16 sensitively. The valve shaft 56 is provided with a thread 74, which is screwable into a corresponding threaded aperture in the housing 12. If the valve shaft is screwed completely into the housing the outlet opening 16 is closed. Furthermore, a suitable washer 60 is inserted between casing and valve shaft. The valve shaft is provided with a thumb wheel 62, which has a graduation (not shown) at the front being graded, for example, for drops/minute or cm3/hour. A suitable marking in relation to which the thumb wheel may be adjusted is provided on the housing. The pitch of the thread 74 is chosen so that it allows the flow rate to be adjusted from zero to 100 drops per minute by a complete rotation of the thumb wheel 62.

For this purpose, the threads are ground or polished.

Between the housing 12 and the thumb wheel 62 of the valve shaft 56 a spring 64 under tension is provided, which may be, for example, a helical spring, preferably a plastics or rubber spring, for example in form of an elastic bellows, which in addition to its resilience offers an additional protection against the penetration of germs in the region of the valve shaft. On one hand, the spring serves for keeping the flow of the infusion solution constant, and on the other hand it serves for counteracting possible suction forces that may occur in the range of outlet opening 16, which may alter the position of the valve shaft. Thus, the spring forces must be greater than the maximum possible suction force, however it must not be so great that the thread of the valve shaft is damaged or deformed. One end of the spring 64 engages the housing, while the other end is engaged in an annular groove 66 within the thumb wheel 62, as shown in Figure 1, whereby the spring is supported and held, however, without affecting turnability of the thumb wheel 62.

The upper end of the housing 12 is provided with an inspection container 46, extending upwardly through the lid 36, the upper end of which is connected to a connecting piece 48 for a tube. At the entrance of the connecting piece 48 into the inspection glass 46 there may be provided a coarse filter 52. Furthermore, a funnel-shaped member 6 8 7 8 may be provided, the outlet opening of which determines the size of drops. The tube connecting piece 48 may be provided with a handle 50 in order to facilitate manipulation.

The appliance according to the invention works as follows: From a liquid container (not shown) via the tube connecting piece 48 there enters a liquid, for example a solution to be injected into a patient, through the coarse filter 52 and the member 54 into the inspection container 46. If the inlet opening 14 is open (as illustrated) the liquid enters through the inlet opening and flows along the valve shaft 20 to the exterior surface of the float 18 and descends around the exterior surface. Then the solution flows down along the curved surface of the wall of the float 18 and the head 26 if the float is provided with such a head. At first, the float 18 rests on the opening of connecting channel 32, which is closed by the head 26. When enough liquid has accumulated in the float chamber 72, float 18 is lifted from connecting channel 32 due to the lifting force so that the liquid may flow through this channel to the outlet opening 16. The cross-section of flow through the outlet opening 16 is adjusted by the nose 58 of valve shaft 56 to a desired flow rate and the liquid then flows through the outlet opening 16 to bore 68 and from there via a tube connecting member (not shown) and a tube to the patient.

If more liquid enters the float chamber 72 through inlet opening 14 than flows away through outlet opening 16, the float will rise until the inlet opening 14 is closed by the conical valve surface 22 of the valve shaft 20 engaging the conical valve seat of inlet opening 14 so that the inlet opening 14 is closed. In operation, the float chamber 72 is constantly vented to the atmosphere via filter 38 and the air vent apertures 44. As the liquid continues to flow out of the outlet opening 16, the level of liquid in the float chamber 72 will drop, so that the float 18 also drops, whereby the inlet opening 14 becomes free again.

Advantageously, the lower part of the float 18, the nose 26 and the guiding pin 30 are formed in such a way that no air-bubbles remain on their surfaces in use.

The connection between ribs 40, 44 and the grooves in housing 12 is advantageously chosen in such a way that the ribs grip suitably within the grooves, so that the lid 36 when it is set on the housing while gripping the filter 38 cannot spring open. The very large surface of the frustoconical filter renders it possible to use a dense or doublelayer filter, which impedes the intrusion of bacteria.

The invention thus provides, at least in its preferred embodiment, an apparatus for controlling the flow of a liquid under gravity which permits an umhampered flow of liquid through the float chamber.

Claims

1. An apparatus for adjusting the flow of a liquid under gravity, comprising a housing defining a float chamber having an inlet and an outlet, a float having a valve shaft at its upper end, the body of said float being the surface of revolution of a convex curve about the longitudinal axis of the body, the upper end of said body tapering towards said valve shaft, said valve shaft having a valve surface liquid defined thereon.which serves in operation for closing the inlet opening when the^ in the float chamber has reached a predetermined level and a manually operable valve for adjusting the cross-section of the outlet opening.

2. An apparatus as claimed in claim 1, wherein the float is substantially egg-shaped.

3. An apparatus as claimed in claim 1 or 2, wherein the angle between the longitudinal axis of the float and the tangent to its surface at its upper end is substantially 45°.

4. An apparatus as claimed in any of claims 1 to 3, wherein a substantially hemi-spherical head made of flexible material is provided on the lower end of the float for closing the outlet opening.

5. An apparatus as claimed in any preceding claim further comprising a guiding pin arranged on the lower end of the float which extends into the outlet from the float chamber.

6. An apparatus as claimed in any preceding claim, further comprising a guiding pin arranged on the upper end of the float which extends into the inlet of the float chamber.

7. An apparatus as claimed in any preceding claim wherein said valve surface is conical and cooperates with a conical seat surrounding the inlet opening.

8. An apparatus as claimed in any preceding claim, wherein the housing is provided with a lid having air vent apertures therein, a filter being arranged between the lid and the housing.

9. An apparatus as claimed in claim 8, wherein the filter is made of a silicon-impregnated, phase-separating filter paper.

10. An apparatus as claimed in claim 8 or 9, wherein the lid and the housing are provided with corresponding circular ribs and grooves, the ribs being engageable within the grooves by a snapping action, the filter being retained between the ribs and the grooves.

11. An apparatus as claimed in any preceding claim, wherein the manually operable valve comprises a concial or frusto-conical valve member having a small cone angle, whereby the cross-sction of the outlet opening is adjustable.

12. An apparatus as claimed in claim 11, wherein the manually further operable valve^comprises a thumb wheel, and a spring arranged between the thumb wheel and the housing the spring being loaded in order to keep the valve member in its desired position.