Patent Description:
There are known breathing systems that comprise a cylinder of a pressurised breathable gas, downstream of which a first pressure reduction stage is provided; downstream of the first stage, at the regulator, the second pressure reduction stage is provided. The first reduction stage allows the breathable fluid to be brought from the pressure of <NUM>-<NUM> MPa (<NUM>-<NUM> bar) which is found in the cylinder to an intermediate pressure of about <NUM> MPa (<NUM> bar).

in addition to the ambient pressure. The second stage further reduces the pressure, bringing it to the ambient value (a function of depth) so that the gas can be breathed in by the user.

<CIT> or <CIT> discloses a known solution in which in the second stage, a valve comprising a stem valve poppet is placed between a supply conduit of the breathable gas under pressure and a mouthpiece.

The stem has a first and a second opposite end and a central conduit connecting them. The first end is intended to prevent the passage of gas towards the mouthpiece whereas the second end leads into a pressure balancing chamber which is in a fixed position. The conduit thus allows the pressure in the balancing chamber to be balanced with the pressure at the valve inlet. Since the second end has a larger pushing surface than the first end, during use there is normally a force present that pushes the valve poppet against the valve inlet. In this manner the passage of the breathable gas towards the mouthpiece is prevented. Negative pressure induced by the user's breathing allows the movement of a diaphragm, which in turn activates a lever that moves the valve poppet away from the valve inlet, thus enabling the supply of the breathable gas to the mouthpiece.

This type of solution is known in the technical field as "upstream valve" because as the intermediate pressure increases, the valve closes more and more (unlike the downstream solutions which, as the intermediate pressure increases, open at a certain point without the need for external intervention; for this reason a second upstream stage needs an overpressure valve which discharges if the intermediate pressure reaches abnormal values due to a malfunction).

The upstream solution described above has some drawbacks, including that if the valve is open and an attempt is made to pressurise the second stage, there is a risk that the valve poppet will never be able to shut off the supply. This is because the balancing chamber, in order to be able to exert its action, needs the gas to penetrate therein and pressurise it sufficiently. If the valve poppet were open, the gas delivered would continue to push the first end of the valve poppet, preventing it from moving near the closed position. Furthermore, a good part of the gas would flow outside the valve poppet towards the mouthpiece without being able to flow through the conduit inside the valve poppet in an amount capable of pressurising the balancing chamber sufficiently.

An alternative solution is further known in which in the second stage, a valve comprising a stem valve poppet is placed between the supply conduit of the breathable gas under pressure and the mouthpiece.

The stem also has an inner central conduit connecting two opposite ends thereof. One of these ends (the first) faces the inlet of the valve and prevents/permits the passage of gas to the mouthpiece. The other end (the second) leads into and slides inside a pressure balancing chamber that is in a fixed position. The conduit thus allows the pressure in the balancing chamber to be balanced with the pressure at the valve inlet. Due to the ratios between the surfaces, the second surface end being smaller than the first (i.e., the situation opposite the case described above), the force exerted by the pressure in the balancing chamber only partly compensates for the force induced by the pressure at the valve inlet. In fact, there is an opposing helical spring that exerts an additional action directly on the stem of the valve poppet to press it against an inlet hole of the valve. The pressure present in the balancing chamber nonetheless helps the opposing spring to maintain the valve poppet in a position in which it prevents the passage of the breathable gas towards the mouthpiece. This configuration, with the spring participating in the closing of the valve, is called "downstream" in jargon, since as the intermediate pressure increases, a point is reached in which the valve opens without the need for external intervention.

Negative pressure induced by the user's breathing brings about a deformation of a diaphragm which in turn induces the shifting of a lever and the distancing of the valve poppet from the inlet hole (overcoming the forces which would compress the valve poppet against the valve inlet). In this manner, the breathable gas flows in a zone surrounding the valve poppet stem and reaches the mouthpiece.

In this solution, the spring is sufficient to keep the valve closed in the absence of pressure. However, the operation under conditions of high respiratory gas demands may be less stable than desired.

In this context, the technical task at the basis of the present invention is to propose a pressure reducing system for a breathing apparatus that overcomes the above-mentioned drawbacks of the prior art.

Furthermore, it is an object of the present invention to provide a pressure reducing system for a breathing apparatus which is capable of avoiding unwanted operations if it is pressurised in certain operating circumstances. The stated technical task and specified objects are substantially achieved by a pressure reducing system for a breathing apparatus comprising the technical features disclosed in one or more of the accompanying claims. Additional features and advantages of the present invention will become more apparent from the approximate, and thus non-limiting, description of a preferred but not exclusive embodiment of a pressure reducing system for a breathing apparatus as illustrated in the accompanying drawings, in which:.

In the accompanying figures, a pressure reducing system for a breathing apparatus is denoted by the reference number <NUM>.

As mentioned previously, the pressure reducing system <NUM> is advantageously used for diving applications, but could also be employed in other applications. With reference to the schematic view in <FIG>, the present description preferably makes reference to a breathing system <NUM> comprising:.

Appropriately, in the course of the present description, intermediate pressure is understood as the pressure between the first and second stages <NUM>, <NUM> (and, therefore, in the preferred application, the pressure immediately upstream of the system <NUM>). For example, the intermediate pressure can be equal to about <NUM> MPa (<NUM> bar) (though it may vary for example with depth).

The reducing system <NUM> comprises a supply conduit <NUM> for supplying a breathable gas under pressure. Such a supply conduit <NUM> typically originates from the sleeve <NUM> coming from the first stage <NUM> connected to the pressurised tank <NUM> of breathable fluid (the gas could also be in liquid form inside the tank <NUM>). The breathable gas can be of various types: compressed air, Nitrox, mixtures of oxygen, nitrogen and helium, or still others.

The system <NUM> also comprises an inspiration mouthpiece <NUM> for a user to breathe in the breathable gas. This enables the user to keep the second stage firmly in their mouth and thus to breathe.

The system <NUM> further comprises a valve poppet <NUM> operatively interposed between the conduit <NUM> and the mouthpiece <NUM>.

The valve poppet <NUM> is movable between a closed position, in which it prevents the passage of the breathable gas from the conduit <NUM> to the mouthpiece <NUM> (see for example <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG>) and at least one open position in which it allows the passage of the breathable gas from the conduit <NUM> to the mouthpiece <NUM> (see for example <FIG>, <FIG> and <FIG>).

The conduit <NUM> comprises an abutment <NUM> against which the valve poppet <NUM> abuts in the closed position and from which it is distanced in said at least one open position. Suitably, the abutment <NUM> is located in a final section of the conduit <NUM>. Suitably, the valve poppet <NUM> is located at an end of the conduit <NUM>.

The abutment <NUM> defines an interface <NUM> that in the closed position is in contact with the valve poppet <NUM> in order to perform a sealing action that prevents the passage of the breathable gas from the conduit <NUM> to the mouthpiece <NUM>. The interface <NUM> is annular. The interface <NUM> is located on an end surface of the abutment <NUM>. Suitably, but not necessarily, it is circular. Suitably the interface <NUM> is transverse, advantageously lying in an imaginary plane which is transverse, preferably orthogonal, to a shifting direction <NUM> of the valve poppet <NUM>.

Such a valve poppet <NUM> is therefore part of a valve that allows or prevents the passage of the breathable gas from the conduit <NUM> to the mouthpiece <NUM>. Suitably such a valve comprises an inlet (which can correspond to the abutment <NUM>), an outlet (which can be a conduit <NUM> which is located downstream of said annular seal). Such a conduit <NUM> can be a by-pass conduit, shown by way of example in <FIG>, <FIG> and <FIG> and not further described, being well known in the technical field. Or such a conduit can be a conduit extending from a seat <NUM> which externally surrounds the valve poppet <NUM> (this solution is also well known in the technical field).

In a zone intended to come into contact with the abutment <NUM>, the valve poppet <NUM> comprises a sealing element <NUM>. Such a sealing element <NUM> is called "pad" in technical jargon. The abutment <NUM> can typically have a thin profile to optimise the seal with the pad. The abutment <NUM> against which the pad is pressed can therefore leave an imprint on the latter (called "marking" in technical jargon).

Conveniently, a sealing area between the conduit <NUM> and the valve poppet <NUM> is not located in a zone internal to the conduit <NUM>.

Suitably the system <NUM> comprises a balancing chamber <NUM> which defines a pressure balancing zone <NUM>. The valve poppet <NUM> is at least partly interposed between the abutment <NUM> and the balancing chamber <NUM>. The valve poppet <NUM> defines a passage <NUM> which places the conduit <NUM> and the pressure balancing chamber <NUM> in fluid communication. The passage <NUM> is a tube/straw. The balancing chamber <NUM> is located behind the valve poppet <NUM> with respect to the flow of the breathable gas coming from the conduit <NUM>.

The expression "balancing chamber" is well known in the technical field, as during operation it enables at least a partial balancing of the force exerted by the pressure of the breathable gas on the valve poppet <NUM> at the abutment <NUM>.

The passage <NUM> extends inside the valve poppet <NUM>. Purely by way of non-limiting example, the passage <NUM> can have an outflow cross section of a size comprised between <NUM><NUM> and <NUM><NUM>.

When the valve poppet <NUM> is in the closed position, during normal operation the balancing chamber <NUM> takes on the pressure value existing at the abutment <NUM>. This is thanks to the gas that flows from the conduit <NUM> to the chamber <NUM> by means of the passage <NUM>. When the valve poppet <NUM> is in the open position, the gas also flows outside the valve poppet <NUM> to the mouthpiece <NUM>. For example in the open position the gas flows into a space interposed between the valve poppet <NUM> and the seat <NUM> which laterally surrounds the valve poppet <NUM> (solution not illustrated) or directly into the by-pass conduit <NUM> which is located immediately downstream of the valve poppet <NUM>.

In the solution of <FIG> the balancing chamber <NUM> remains in a fixed position. The valve poppet <NUM> moves from the closed position (see <FIG>, <FIG>) to an open position (see for example <FIG>, <FIG>) as a consequence of the negative pressure determined by the user on the mouthpiece <NUM> that calls gas to inhale it (as better explained below). Once the negative pressure induced by the user's breathing ends, the valve poppet <NUM> returns from the open position to the closed position due to the pressure exerted by the balancing chamber <NUM>. In fact, in this step the pressure in the balancing chamber <NUM> is the same as the pressure in the conduit <NUM>, but the force that causes the valve poppet <NUM> to close is greater than the one opposing it (as a consequence of the fact that the pushing surface that is usable in a closing direction of the valve poppet <NUM> is larger than the pushing surface that is usable in the opening direction; this is because inside the chamber <NUM> the valve poppet <NUM> has a pushing surface for closing that is larger than the surface of the valve poppet <NUM> which in the closed position faces the section for the passage of gas at the abutment <NUM>).

In the case of <FIG> (upstream solution), suitably, an elastic spring is absent between the valve poppet <NUM> and the balancing chamber <NUM>. In the solution of <FIG> (downstream solution) instead an elastic spring <NUM> is present between the valve poppet <NUM> and the balancing chamber <NUM>. Such a spring <NUM> pushes the valve poppet <NUM> to assume the closed position.

One section of said passage <NUM>, in at least one of said open positions extends in the supply conduit <NUM> beyond said interface <NUM>.

A part of the passage <NUM> is surrounded by the abutment <NUM>.

The valve poppet <NUM> is movable between the closed position and a position of maximum distancing from the interface <NUM>. Advantageously, the passage <NUM> extends towards the supply conduit <NUM> beyond said interface <NUM> for at least <NUM>% (but preferably for <NUM>% and more) of the positions assumed between the closed position and the position of maximum distancing.

Suitably the passage <NUM> extends in the supply conduit <NUM> beyond said interface <NUM> in all of said open positions of the valve poppet <NUM>. The annular interface <NUM> is an annular line or strip and the passage <NUM> crosses a hole defined by said annular interface in any open position of the valve poppet <NUM> (and consequently also in a closed position of the valve poppet <NUM>).

The conduit <NUM> extends towards the conduit <NUM> beyond the zone of the valve poppet <NUM> destined to abut the interface <NUM>. Suitably, it protrudes cantilevered.

The system <NUM> comprises an actuator (a lever <NUM>) for shifting the valve poppet <NUM> along a travel path having as opposite travel limits:.

Conveniently, the reducing system <NUM> comprises a diaphragm <NUM> which is deformable by the user's breathing in. In fact, by breathing in, the user causes a negative pressure that deforms the diaphragm <NUM>, causing it in turn to shift the lever <NUM>. This in turn induces a shifting of the valve poppet <NUM> from the closed position to one of the open positions, thereby permitting the passage of the breathable gas. Once the effect of breathing in is over, the lever <NUM> goes back into the original position.

The valve poppet <NUM> has a preponderant extension direction <NUM>. In fact, it is a stem valve poppet. It comprises a flat zone <NUM> which extends longitudinally, parallel to the preponderant extension direction <NUM>. The flat zone <NUM> connects flaps <NUM> facing said abutment <NUM> and interaction means of the valve poppet <NUM> with the lever <NUM>. The flat zone <NUM> has the purpose of minimising the risk of oscillations of the valve poppet <NUM> during opening. In fact, when the valve poppet <NUM> passes from the closed to the open position, the gas coming from the conduit <NUM> is introduced not only into the passage <NUM>, but also flows outside the valve poppet <NUM>. Every protuberance/wall of the valve poppet <NUM> perpendicular to the direction of flow outside the valve poppet itself acts like a "sail" which, when struck by the flow of gas, causes the valve poppet <NUM> to move rearward and disrupts the correct movement thereof. This can bring about undesirable uncertainties in the shifting of the valve poppet <NUM>.

Conveniently one end of the passage <NUM> defines a breathing gas inlet port. This inlet opening is arranged transversely to the flow of breathing gas. This inlet opening faces a section of the duct <NUM> located upstream of the shutter <NUM>.

The valve poppet <NUM> suitably comprises a main portion <NUM> (which in the closing position does not extend beyond the annular interface <NUM>).

In particular, the passage <NUM> comprises:.

Such an extension <NUM> extends from the main portion <NUM> towards the conduit <NUM> (therefore upstream of the main portion <NUM> with respect to the direction of the gas in the conduit <NUM>).

The tubular extension <NUM> outside the main portion <NUM> has a length comprised between <NUM> and <NUM> millimetres. By way of non-limiting example, the maximum shift of the valve poppet <NUM> with respect to the abutment <NUM> could be approximately <NUM>. Preferably the passage <NUM> extends from the sealing element <NUM> for about <NUM>-<NUM>, so as to have at least <NUM>-<NUM> for "drawing" the breathable gas.

Suitably, the tubular extension <NUM> extends cantilevered from the main portion <NUM>. In particular, it extends cantilevered upstream with respect to the flow of the breathable gas in the conduit <NUM>. Suitably the tubular portion <NUM> and the extension <NUM> have the same passage section (or in any case they differ by less than <NUM>%). Suitably the main portion <NUM> faces the abutment <NUM> and is entirely contained in one of the two half-spaces with respect to the imaginary plane in which the annular interface <NUM> lies. The extension <NUM> crosses such an imaginary plane and extends upstream.

In the solution exemplified in <FIG> the tubular extension <NUM> is in a single body with the inner tubular portion <NUM> of the valve poppet <NUM>. In such a case the sealing element <NUM> (pad) can be a simple rubber ring fitted around the passage <NUM>.

In the solution exemplified in <FIG> and in the solution exemplified in <FIG> the extension <NUM> comprises a separate tube applied to the valve poppet <NUM>. In particular, the separate tube is applied upstream of the tubular portion <NUM> obtained in the main portion <NUM>. Suitably the separate tube and the tubular portion <NUM> are consecutive. For example the separate tube can be inserted into the sealing element <NUM> (pad) for a section.

The system <NUM> can comprise (see <FIG>) a movement system <NUM> for moving the balancing chamber <NUM> towards (up to) the abutment <NUM> to move the valve poppet <NUM> from the open position to the closed position upon the occurrence of at least one preset operating condition (typically depressurisation or blockage of the valve poppet <NUM> as a result of freezing).

In particular, <FIG> shows a situation in which there is a depressurisation upstream of the system <NUM>. <FIG> instead shows the system <NUM> pressurised and with the valve poppet <NUM> in the closed position. When the pressurised system <NUM> and the user breathes, it generates a negative pressure that moves the lever <NUM> (as already explained above) which in turn causes the opening of such a valve poppet <NUM> (thus passing from the situation of <FIG> to that of <FIG>).

As better explained below, the movement system <NUM> intervenes spontaneously if there is a depressurisation immediately upstream of the abutment <NUM> (depressurisation of the second stage, typically occurs when the pressure immediately upstream of the abutment <NUM> is brought to "ambient pressure") or enables a manual intervention of the user in the occurrence of freezing which blocks the valve poppet <NUM> in the open position. In this case the movement system <NUM> pushes the chamber <NUM>, causing the passage from the situation of <FIG> to that of <FIG>.

The balancing chamber <NUM> is therefore movable relative to the abutment <NUM> (although the movement in actual fact only occurs under certain conditions). The movement means <NUM> induces the movement of the valve poppet <NUM> up to the closed position as a consequence of the push received from the balancing chamber <NUM> in its travel towards the abutment <NUM> (thus the movement system <NUM> pushes the balancing chamber <NUM>, which in turn pushes the valve poppet <NUM>). The balancing chamber <NUM> is conveniently shaped like a cup having an opening through which the valve poppet <NUM> is inserted. Conveniently, the end of the valve poppet <NUM> that extends into the balancing chamber <NUM> comprises an annular gasket (O-ring). During a travel of the balancing chamber <NUM> as it shifts towards the abutment <NUM>, a back wall <NUM> of the balancing chamber <NUM> is intended to push the valve poppet <NUM> against the abutment <NUM> (this is exemplified in the passage from <FIG>). Therefore, the system <NUM> can take on a configuration in which the back wall <NUM> of the balancing chamber <NUM> abuts against and pushes the valve poppet <NUM> towards the closed position. The balancing chamber <NUM> slides along the seat <NUM> under the action of the movement system <NUM>. In particular, the balancing chamber <NUM> slides along the seat <NUM> parallel to a preponderant extension direction of the valve poppet <NUM>.

The movement system <NUM> for moving the balancing chamber <NUM> can be of varying type. For example, behind the chamber <NUM>, the movement system <NUM> of the balancing chamber <NUM> could comprise a spring <NUM> and/or a manually operable pusher <NUM> (in case of emergency, e.g., freezing of the system <NUM>) and/or a further pressurisation chamber, etc..

In the appended figures of the drawings, reference numeral <NUM> denotes a pressurisation method. Suitably, such a method is implemented by a pressure reducing system <NUM> having one or more of the features described above.

Suitably the pressurisation method is implemented starting from a configuration in which the valve poppet <NUM> is spaced from the abutment <NUM> and the system <NUM> is depressurised.

The present invention achieves important advantages.

The tube which exits from the valve poppet <NUM> in the direction of the sleeve (the conduit <NUM>), allows to "draw" breathable gas before the breathable gas itself reaches the annular opening between the abutment <NUM> and the pad of the valve poppet <NUM>, thereby managing to ensure pressurisation in the balancing chamber <NUM>.

Thereby, even if the system <NUM> is pressurised with the valve poppet <NUM> open, the system manages to draw the breathable gas through such an extension and to convey it to the chamber <NUM> to close the valve poppet (alternatively, if the breathable gas begins to flow directly towards the mouthpiece, the system <NUM> could go into continuous delivery, preventing the valve poppet <NUM> from closing).

Claim 1:
A pressure reducing system for a breathing apparatus comprising:
i) a conduit (<NUM>) for supplying a breathable gas under pressure;
ii) a mouthpiece (<NUM>) for inspiration of the breathable gas by a user;
iii) a valve poppet (<NUM>) operatively interposed between the conduit (<NUM>) and the mouthpiece (<NUM>); said valve poppet (<NUM>) being movable between a closed position, in which it prevents the passage of the breathable gas from the conduit (<NUM>) to the mouthpiece (<NUM>), and at least one open position in which it permits the passage of the breathable gas from the conduit (<NUM>) to the mouthpiece (<NUM>); said conduit (<NUM>) comprising an abutment (<NUM>) against which the valve poppet (<NUM>) abuts in the closed position and from which it is distanced in said at least one open position; said abutment (<NUM>) defining an annular interface (<NUM>) which in the closed position is in contact with the valve poppet in order to perform a fluid-dynamic sealing action that prevents the passage of the breathable gas from the conduit (<NUM>) to the mouthpiece (<NUM>); the interface (<NUM>) being located on an end surface of the abutment (<NUM>);
iv) a balancing chamber (<NUM>) that defines a pressure balancing zone (<NUM>), said valve poppet (<NUM>) being at least in part interposed between the abutment (<NUM>) and the balancing chamber (<NUM>); the valve poppet (<NUM>) defining a passage (<NUM>) that places the conduit (<NUM>) and the pressure balancing chamber (<NUM>) in fluid communication;
said passage (<NUM>), in at least one of said open positions extending in the supply conduit (<NUM>) beyond said interface (<NUM>);
characterised in that said passage (<NUM>) extends in the supply conduit (<NUM>) beyond said interface (<NUM>) in all of said open positions of the valve poppet (<NUM>).