The present invention concerns a flow control valve for use in connection with stepwise regulation of compressed gases with a flow less than or equal to 25 1/min, the flow control valve including flow control means including a flow disc and a spindle, the flow disc including a number of flow apertures with an internal wall, and the flow disc being connected with the spindle, wherein the spindle is arranged for rotation about an axis, wherein the flow apertures by rotation of the spindle about the axis are moved relatively and brought into a position in relation to at least one discharge opening for yielding a stepwisely determined flow through one or more the flow apertures. The invention also relates to a method for making such a flow control valve. Description of Prior Art

It is common knowledge to use flow control valves in connection with use of gas, including during the use of medical gases, such as e.g. oxygen, which are supplied to a user via a mask or via tubes in the nose. Such gases are typically stored at high pressure in a pressure container and supplied to the point of consumption or the user at reduced pressure and in a predetermined amount which is typically measured in litres per minute (LPM). Such a valve with integrated pressure regulation ensures, for example, that the user is supplied with a pressure which is as constant as possible and independently of how much pressure is left in the pressure container.

The prior art types of pressure reduction valves are typically made with a valve function ensuring that the pressure from the pressure container is reduced to a suitably low level - typically to a pressure of about 4.5 bar and with a flow control possibility where a flow between 0 and 25 LPM can be set. This regulated gas pressure is also called the discharge pressure. Some valves will be designed with a pressure outlet such that the consumer can connect equipment and use the regulated discharge pressure of the valve. In addition, the valves can include a flow outlet. The flow outlet is typically used for therapy of patients with medical gases, as e.g. oxygen. In order to adapt the flow to the need of the patient for a certain amount of gas, the flow is typically adjustable by means of a handwheel or similar. There are valves that include both a flow outlet and a pressure outlet, and there are valves that only include one of these outlets. In the prior art types of flow controls, typically so-called loose flow discs are used. These flow discs are made with a plurality of rather small openings which by proper positioning allow a given amount of gas to pass through these openings. These loose flow discs, however, imply several inexpediencies as they i.a. can be turned incorrectly during mounting of the valve itself, and furthermore they may be worn such that they do not stand in the intended position when the handwheel is operated such that the real flow rate will deviate from the flow rate set by the user. The result of a wrong disposition of the loose flow disc or of the loose flow disc being worn and broken can appear fatal as an intended amount of gas, e.g. oxygen, is not supplied to a patient. Such loose flow discs according to the prior art solutions are typically made with a central hole which is provided on a socket or carrier on a spindle which is connected with a handwheel for operating the flow control itself. When the handwheel is operated, the socket/carrier will provide that the flow disc is rotated with the spindle when the latter is rotated about its rotary axis as the shape of the socket/carrier corresponds to a cutout in the flow disc, thereby transmitting the rotary movement to the flow disc.

In order to ensure sufficient rigidity and wearability in the flow discs, these are typically made of a relatively thin steel or metal sheet rather than in a plastic material, typically with a thickness from under 0.1 mm and up to a thickness of several tenths of a millimetre, where the openings made for allowing correct and balanced flow are rather small. In order to attain required strength in the flow disc, it is, as mentioned, typically made of metal, and the said small openings are typically made by laser cutting which is obviously to be preferred as openings with an exact cross-section of the mentioned sizes are not readily made in other ways. The reason for making these flow discs of a thin material is that the small openings cannot be made with the required accuracy in a thicker material.

The smallest of these openings are typically with a diameter less than 0.1 mm, and the openings can be made in groups of two such that by erroneous positioning of the handwheel and thereby of the flow disc between two steps there will still be communication with at least one of the two openings, and the patient will still be supplied with gas thereby.

When cutting/forming holes or openings as mentioned by laser or by other types of tools, a burr or sharp edge will inevitably will formed at one side of the flow disc. This burr or sharp edge is problematic in that it may damage the packing or packings located in the flow control valve. It is particularly difficult that this problem typically will arise only after adjusting the flow control many times. The packing will then be intact as it has been produced and tested, but after the valve has been in use for a longer period of time, difficult situations can arise if the packings in the flow control have been destroyed. The flow control will then no longer yield the desired amount of gas, without the user of the valve necessarily noting this fact.

It is the object of the invention to indicate a flow control valve with flow control means where the said inexpediencies are countered, where the surfaces on the flow controlling means that come in contact with packings are free from burrs and sharp edges. Furthermore, it is the object of the invention to indicate a solution by which it is ensured that the flow disc cannot avoid being turned when operating a handwheel or similar for regulating the flow allowed by the flow control valve.

Description of the Invention

As mentioned in the introduction, the present invention concerns a flow control valve for use in connection with stepwise regulation of compressed gases with a flow less than or equal to 25 1/min, the flow control valve including flow control means including a flow disc and a spindle, the flow disc including a number of flow apertures with an internal wall, and the flow disc being connected with the spindle, wherein the spindle is arranged for rotation about an axis, wherein the flow apertures by rotation of the spindle about the axis are moved relatively and brought into a position in relation to at least one discharge opening for yielding a stepwisely determined flow through one or more the flow apertures.

Besides stepwise regulation of compressed gasses with a flow less than or equal to 25 1/min, the flow control valve also has a least flow step which is less than 10 1/min.

The new feature of a flow control valve according to the invention is that the flow disc includes a number of through-going apertures/flow apertures, the apertures at one first side of the flow disc formed with a first cross-sectional area and on the second side of the flow disc formed with a second cross-sectional area, where either at the first side or at the second side of the flow disc or between these sides of the flow disc there is formed a flow aperture with a cross-sectional area which is less than either the first cross-sectional area or the second cross-sectional area, or both areas. In the following, the term "opening" will be used for the openings present in the first side of the flow disc and which are larger than the "flow apertures" which are the apertures formed in the second side of the flow disc. Thus it is the flow apertures that determine the flow, and the openings are larger and therefore do not or only to a limited degree determine the size of the flow.

Several new and surprising advantages can hereby be achieved which will be discussed and elucidated in the following. Among others, sharp edges on the mentioned openings that may come in contact with the packing can be obviated. In a preferred variant of a flow control valve according to the invention, the first cross- sectional area of an aperture may advantageously be formed at the side of the flow disc which in contact with one or more packings, and which is moved in relation to the discharge opening when operating the flow control valve. These larger openings - compared with the flow apertures - on the first side of the flow disc are obviously not, or only to a limited degree, controlling the flow, but since they are formed on the side of the flow disc in contact with one or more packings internally of the valve, and since they are larger than the flow apertures, they can be produced such that the edge of the opening is broken. Thereby is achieved an improved and more gentle contact between the flow disc and one or more packings. The used packings are typically O-rings disposed in a recess around the discharge opening, and when the flow disc is turned in relation to the discharge opening, the openings are moved past the packing whereby the latter can be damaged - in particular if the openings are sharp on the edges, either in the form of a sharp-edged hole or because there is a burr on the edge of the opening.

In order to protect the packing as much as possible, it is therefore most expedient to let the larger opening face the packing as it can be made such that it protects the packing. Examples thereof will be described below. The flow apertures, which are very small and typically made by laser cutting, cannot be made with any form of rounded or broken edge as the apertures are simply too small for this operation.

A method according to the invention can include making these openings and apertures such that apertures with a first cross-sectional area on and from a from one first side of the flow disc are formed, and that flow apertures with a second cross-sectional area on the second side of the flow disc are formed, where the first cross-sectional areal is greater than the second cross-sectional area. This means that it is possible to use suitable methods for forming the said openings and flow apertures whereby problems with burrs and with sharp edges are avoided. In other words, it is so that the openings at the first side of the flow disc have a size which is greater than the smaller and thereby flow controlling aperture formed at the second side of the flow disc.

The flow apertures can be edged but will preferably be circular and cylindrical. They may, however, be conical and with other continuous or discontinuous surfaces on the internal walls in the flow apertures. For example, it may be so that a conical opening may be drilled or formed in other way from the first side and a cylindrical flow aperture from the second side of the flow disc. A flow control valve of this type is expected to last 10 years of use, which also can be quantified by about 4000 actuations. Therefore, it is rather important that the packings are not subjected to unnecessary wear in the form of damage from the said sharp edges and burrs formed in connection with the making of the flow apertures.

In a variant of a flow control valve according to the invention, the flow disc can include openings at the first side with a first depth into the flow disc, and where the flow disc at the second side includes flow apertures with a second depth into the flow disc, wherein the openings and the flow apertures in the two sides on the flow disc are interconnected. These openings as well as flow apertures may advantageously be circular and at least partially cylindrical. For example, openings can be drilled from the first side and partially through the thickness of the flow disc. These openings will typically be made such that a bottom that is left will be a few tenths of a millimetre thick. By this thickness it is possible afterwards to laser cut flow apertures with the required precision through this bottom such that flow apertures with a depth corresponding to the depth of the thickness of the bottom are formed and with a lesser cross-sectional area than the openings on the other side of the flow disc. A thicker flow disc is hereby achieved while at the same time the flow apertures formed on the second side, e.g. by laser cutting, have the required tolerance, as the material thickness at the point where the flow aperture is established is not larger than the prior art flow discs. However, the very great advantage is that we have a markedly increased thickness and rigidity of the flow disc, and in cases where a loose flow disc is used, the carrier between the flow disc and the spindle can hereby be designed such as to resist wear in a much better way.

In a variant of a flow control valve according to the invention, the flow disc can also be made such that it includes openings at the first side with a first depth into the flow disc, where the flow disc at the second side includes opposing openings with a second depth into the flow disc, wherein the opposing openings are mutually connected via flow apertures which thereby open onto an opening with a greater cross-sectional area towards both sides of the flow disc. By such a flow disc, a rounding or bevelling of openings can be performed at both sides of the flow disc, and both sides are therefore suited for contact with packings without the latter being inexpediently worn. In a particularly preferred variant of a flow control valve according to the invention, flow apertures on at least the first side of the flow disc may include a bevelled, rounded or otherwise broken transition between the internal wall of the flow apertures and the first side of the flow disc. Hereby is ensured that there are no sharp edges to damage the packing as mentioned above.

A flow control valve according to the invention can include that the flow disc is a loose flow disc arranged in mechanical connection with the spindle, where the spindle is directly or indirectly connected with an operating means, e.g. a handwheel. Such a loose flow disc may advantageously have a thickness which is appreciably greater than the mentioned 0.2 to 0.3 mm, as for example it can be between 1 and 5 mm and thereby appear with a markedly greater rigidity and with a markedly enhanced ability to ensure that the flow disc can be actuated during rotation of the spindle. This safeguard can e.g. be provided by making the spindle with a socket where the socket has a shape corresponding to a central cutout in the flow disc and possibly with other cutouts and projections that only enable a correct and precise disposition of the loose flow disc on the spindle. The flow disc can be arranged between a head on the spindle and the surface in the control valve where the discharge opening is located, but it may as well be fixed to one end of the spindle by a screw or similar.

A special variant of a flow control valve according to the invention includes that the flow disc can be a fixed flow disc where the flow disc is an integrated and contiguous part of the spindle, where the spindle is directly or indirectly connected with an operating means, e.g. a handwheel. By such a solution the spindle with flow disc can be made as joined unit, e.g. in a machining unit where the almost finished flow disc with spindle is formed by chip-removing processes. The smaller flow apertures can subsequently be established in the second side of the flow disc, as these are made in the relatively thin bottom of the flow openings made from the first side of the flow disc.

A possible method according to the invention is that one or more apertures with a first cross-sectional area on the first side of the flow disc are formed by machining, and that one or more flow apertures with a second cross-sectional area on the second side of the flow disc are formed by laser working from the first side of the flow disc. I.e. from the same side as the one in which the first and large openings are made. This can be advantageous, depending on which equipment is used, and on all process steps possibly can be performed in one fixing or in as few fixings as possible.

Another possible method according to the invention is that one or more apertures with a first cross-sectional area on the first side of the flow disc are formed by machining, and that one or more flow apertures with a second cross-sectional area on the second side of the flow disc are formed by laser working from the second side of the flow disc. As described above, the choice depends on specific considerations concerning the production method itself and the individual process steps. However, there is an immediate advantage by the latter method as a possible burr arising by formation of flow apertures by laser cutting will be located at the bottom of the first flow openings formed from the first side of the flow disc. Thus there is no risk that such a burr comes into contact with a packing as it sits protected in the larger hole. A second and at least just as important detail is that the apertures formed by laser cutting can be performed very accurately, partly because only a small part of the real thickness of the flow disc is to be cut through, and partly because the laser cutter head can come very close to the workpiece during the cutting.

By the invention is thus indicated a flow disc which minimises wear and risk of damage on the packing or packings to seal on the flow disc, and which at the same time reduces the risk that a carrier between a flow disc and a spindle is worn, and that the patient thereby receives a different flow than expected. This is generally achieved by having a thicker flow disc with exact flow apertures at one side which only extend through part of the thickness, whereas the rest of the thickness has larger openings that do not or only to a limited degree act as limitations. Short Description of the Drawing

The invention is described in more detail with reference to the drawing, wherein: Fig. 1 shows a valve with integrated pressure and flow control with stepwise setting of flow.

Fig. 2 shows the same pressure and flow control valve as in Fig. 1, but here partly in section.

Fig. 3 shows detail A on Fig. 2.

Fig. 4 shows a spindle with fixed flow disc in 3D and from a first angle.

Fig. 5 shows a spindle with fixed flow disc in 3D and from a second angle.

Fig. 6 shows a sectional drawing of a spindle with fixed flow disc.

Fig. 7 shows a detail of a flow aperture from Fig. 6.

List of designations:

1 valve with integrated pressure and flow control

2 handwheel for stepwise setting of flow

3 flow outlet

4 spindle

5 housing for flow outlet

6 O-ring on spindle

7 Flow Disc

8 discharge opening

9 packing at discharge opening

10 discharge duct

11 first side on flow disc

12 openings with a first cross-sectional area

13 connection for handwheel

14 recess for O-ring

15 second side on flow disc

16 flow apertures with a second cross-sectional area

17 bevelling

18 internal wall in opening

19 bottom in opening

Detailed Description of Embodiments of the Invention In Fig. 1 appears a valve 1 with integrated pressure and flow control with stepwise setting via a handwheel 2 of the flow of gas conducted out of the flow outlet 3. By turning the handwheel 2, the flow through the flow outlet 3 can be increased and reduced, respectively, and also be shut off. The actual flow for which the valve 1 is set is here represented by a cutout in the handwheel 2, and in this case the flow is set to 0 1/min.

In Fig. 2 appears the same valve 1 as shown in Fig. 1, but shown here partly sectioned in the part of the valve 1 concerning flow regulation as such. By a circle A is indicated an area shown in enlarged version in Fig. 3.

Fig. 3 shows an example of how a spindle 4 is mounted in the flow outlet 3 housing 5 in the upper part of the latter. On the spindle 4 itself is arranged an O-ring 6 sealing between the spindle 4 and the housing 5, and at the visible end of the spindle 4 is arranged a fixed flow disc 7. In the housing 5 is arranged a discharge opening 8, and in a recess at the discharge opening 8 is arranged yet an O-ring 9 having the purpose of ensuring that only the intended amount of gas is allowed to flow out through the discharge duct 10 and further out of the flow outlet 3. As it appears on this Figure, the flow disc 7 is formed in one piece with the spindle, meaning that the flow disc 7 itself cannot avoid being carried with/actuated when the spindle 4 is turned about its longitudinal axis via the not shown handwheel 2.

In Fig. 4 is seen a spindle 4 with fixed flow disc 7, on the first side 11 of which there are arranged a number of sets of openings 12 with a first cross-sectional area. At one position there is only one opening 12, whereas at the other positions there are two openings 12 for each flow rate, meaning - as also mentioned in the introduction - that in case of faulty positioning of the handwheel 2 and thereby of the spindle 4 and the flow disc 7 between two positions, the gas supply is not shut off, but the flow is only restricted. This is, of course, not optimal, but may be certainly be preferred to a completely closed flow control valve. By having two openings 12 and two flow apertures 16 for each position, there will always be about half of the intended amount of gas through the flow disc 7 and out of the discharge duct 10. At its one end, the spindle 4 has a connection 13 for a not shown handwheel 2 and a recess 14 for the mentioned O-ring 6, whereas at the other end of the spindle 4 there is arranged a flow disc 7. It appears from the Figure that all of the mentioned openings 12 with a first cross-sectional area are cylindrical, and that they are equally large except one of these openings 12'. This is possible since it is not these openings 12 that are the controlling flow apertures as this is provided for by the flow apertures 16, but in principle are only formed in order to perform a bevelling or rounding of the transition from the internal surface of the opening to the first side 1 1 on the flow disc 7.

On Fig. 5 appears the spindle 4 with flow disc 7, but seen here from the other end. Thus is here seen the second side 15 of the flow disc 7. On this second side 15 of the flow disc 7 are seen flow apertures 16 with a second cross-section compared with the openings 12 on the first side 11 of the flow disc 7. These flow apertures 16 are determining the amount of gas that may pass the flow control, and as it also appears from the Figure the flow apertures 16 have different sizes in pairs around the flow disc 7 - again except one flow aperture 16'. The shown flow apertures 16 are arranged immediately coinciding with the openings 12, which will be seen in the subsequent Figure.

Fig. 6 shows a cross-section of a spindle 4 with a fixed flow disc 7, where it is particularly interesting to study the design of individual openings 12 and flow apertures 16 on the first side 1 1 and the second side 15 on the flow disc 7, respectively. On the first side 11 of the flow disc 7 there is made a bevelling 17 (see Fig. 7) between the internal wall 18 of the opening 12 and the first side 11 of the flow disc 7, which has a very positive effect on the effect exerted on the packing, i.e. on the packing 9 at the discharge outlet 8. When the edge is provided with a bevelling 17, the flow disc 7 is sliding appreciably easier in relation to the packing 9 which then gets less worn and thereby increased service life. On the other side 15 of the flow disc 7 are seen flow apertures 16 with reduced cross-sectional area, but the most interesting is that this flow aperture 16 is formed through a relatively thin bottom 19 compared with the opening 12, meaning that the flow aperture 16 can be made very precisely with e.g. laser cutting, and at the same time a rigid and robust flow disc 7 can be provided. Finally, Fig. 7 shows an enlarged detail of a flow aperture arrangement where the thickness of the bottom 19 appears more clearly and where the bevelling 17 is also more clearly seen.