WO2024003958A1

WO2024003958A1 - Valve apparatus for delivering gas, and corresponding method

Info

Publication number: WO2024003958A1
Application number: PCT/IT2023/050152
Authority: WO
Inventors: Michele Bortoliero; Nicola Lollo
Original assignee: Sit S.P.A.
Priority date: 2022-06-27
Filing date: 2023-06-27
Publication date: 2024-01-04

Abstract

A valve apparatus (10) for delivering gas comprises a duct (11) for the passage of a gas extending along a longitudinal axis (X) and having an inlet aperture (12) and an outlet aperture (13), first valve means (15) configured to cooperate with the inlet aperture (12) to allow or prevent the flow of said gas and second valve means (21) configured to cooperate at least with a valve seating (22) in order to close said valve apparatus (10). The invention also concerns a mixing device (100) comprising a valve apparatus (10) and a method for delivering a gas.

Description

“VALVE APPARATUS FOR DELIVERING GAS, AND CORRESPONDING METHOD”

FIELD OF THE INVENTION The present invention concerns a valve apparatus for delivering gas to a gas- powered user device, such as for example a burner of a boiler, a heating plant or suchlike.

The valve apparatus according to the invention is suitable both to guarantee safety in the delivery of the gas and also to allow a controlled and precise modulation of the quantity of gas fed.

BACKGROUND OF THE INVENTION

Valve apparatuses are known, for delivering gas to heaters or fireplaces, which comprise a single safety valve which has the task of closing a passage aperture for the gas in the event of any malfunctions or lack of electrical power, in which the safety valve is made in the form of a solenoid valve and is associated with elastic means which return it into position when it is not powered with an electric current.

These valve apparatuses have the advantage of having a limited cost, but are not suitable to be applied to a burner for a heating plant, since the legislation that regulates such applications requires that there should be at least two safety valves present, so as to guarantee a sealing redundancy to prevent the passage of gas when the valve apparatus and the burner are not in operation.

It is also known that in applications relating to heating plants it is necessary to provide a regulation of the quantity of gas that is fed on each occasion, so that the valve apparatuses used in them generally comprise at least two safety solenoid valves, which can be coaxial or separate one from the other, a pressure regulator and/or a flow regulator, which are generally connected to respective drive means.

These valve apparatuses are therefore complex and expensive, requiring a large number of components to allow on the one hand to hermetically close the valve, and on the other hand to modulate the quantity of gas delivered, in particular when a precise and reliable modulation of said quantity is required.

W02007/098790A1 describes a valve unit for controlling the supply of a fuel along a duct, comprising a safety solenoid valve and a pressure regulator, each comprising respective shutters independent of each other and mobile along axes parallel to each other.

WO2019/116407A1 describes a valve apparatus for delivering gas comprising a safety valve, a pressure regulator and a flow regulator independent of each other, provided with respective shutters and actuators acting on axes parallel to each other.

EPl 106922 describes a valve for controlling a gas flow of a known type.

There is therefore a need to perfect and make available a valve apparatus for delivering gas which overcomes at least one of the technical disadvantages disclosed above. One purpose of the present invention is to provide a valve apparatus which is simple and inexpensive, and which allows to prevent an accidental leakage of gas.

Another purpose of the present invention is to provide a valve apparatus which allows a precise and reliable modulation of the quantity of gas delivered.

Another purpose is to provide a valve apparatus which is simple to use and has a limited number of components.

Another purpose is to provide a valve apparatus which allows the quantity of gas delivered to be changed simply and quickly, even during operation.

Another purpose is to provide a valve apparatus which is compact and has limited sizes. Another purpose of the invention is to provide a device for mixing a first and a second gas which is compact and simple to use and install.

Another purpose of the invention is also to perfect a method for delivering gas which allows to modulate the quantity of gas delivered.

The Applicant has devised, tested and embodied the present invention to overcome the shortcomings of the state of the art and to obtain these and other purposes and advantages.

SUMMARY OF THE INVENTION

The present invention is set forth and characterized in the independent claims. The dependent claims describe other characteristics of the present invention or variants to the main inventive idea.

In accordance with the above purposes and to resolve the technical problem disclosed above in a new and original way, also achieving considerable advantages compared to the state of the prior art, a valve apparatus for delivering gas according to the present invention comprises a duct for the passage of a combustible gas extending along a longitudinal axis and having at least an inlet aperture and an outlet aperture and first valve means which are configured to cooperate with the inlet aperture to allow or prevent the flow of the combustible gas therethrough. In accordance with one aspect of the present invention, the valve apparatus also comprises second valve means, elastic means, and a movement unit. The second valve means are configured to cooperate both with a valve seating made in the duct between the inlet aperture and the outlet aperture, in a closed configuration of the valve apparatus, and also to cooperate with the outlet aperture in an operating configuration of the valve apparatus in order to adjust a passage section of the outlet aperture.

In accordance with another aspect of the present invention, the second valve means are associated both with the elastic means and also with the movement unit, and in the closed configuration they are subjected to the action of the elastic means, while in the operating configuration they are subjected to the movement unit.

The second valve means effectively perform a double function, that is, close the valve seating and therefore the duct when there is no electrical power supply or there is a malfunction so as to prevent the flow of the combustible gas, and modulate the flow rate of the gas itself, since by modifying the passage section of the outlet aperture it is possible to modify the gas flow rate and therefore the quantity of combustible gas fed per unit of time.

In accordance with one aspect of the present invention, the first valve means comprise a solenoid valve having an electric circuit and a first shutter which is associated with a first elastic element configured to stress it toward a position of closure of the inlet aperture.

In accordance with one aspect of the present invention, the second valve means comprise a second shutter associated with a second elastic element configured to stress the second shutter toward a position of engagement with the valve seating, in such a way as to prevent the passage of combustible gas. The first and second elastic element both act along the longitudinal axis of the duct. In particular, the two elastic elements act in opposite senses with respect to each other in the closed condition of the valve apparatus.

The first and second elastic elements intervene in particular when the valve apparatus is not powered, allowing to return the respective mobile shutters to a position in which they close the inlet aperture and the valve seating, respectively, so as to obtain a double closure of the passage of the gas upstream of the outlet aperture, providing the double safety required for applications aimed at burners in heating systems.

In accordance with one aspect of the present invention, the inlet aperture is made on a plane orthogonal to the longitudinal axis and it puts the duct in communication with a channel for feeding the combustible gas.

In accordance with some embodiments, the second shutter is made of flexible and/or deformable material, suitable to flex and define a radial seal with the duct.

According to another aspect of the present invention, the outlet aperture is made on a lateral wall of the duct and the second shutter cooperates, with a lateral edge thereof, with the outlet aperture in order to open and close it.

In accordance with some embodiments, the outlet aperture has a diverging shape between a front part facing toward the inlet aperture and a rear part opposite thereto, so that, as a function of the position of the second shutter with respect to the outlet aperture, it is possible to provide a more punctual modulation of the flow rate of combustible gas.

In accordance with another aspect of the present invention, the valve apparatus comprises a unit for moving the valve means and actuator means configured to displace the movement unit at least into a first operating position in which it cooperates with the first valve means in order to open the inlet aperture, and into a plurality of second operating positions in which it cooperates with the second valve means in order to adjust their position with respect to the outlet aperture and modulate the flow rate of combustible gas.

In accordance with some embodiments, the movement unit comprises a rod which is mobile along the longitudinal axis, and the actuator means comprise a drive member and transmission members configured to transfer motion from the drive member to the mobile rod. In accordance with one aspect of the present invention, the transmission members are of the rack type and comprise a toothed portion made on the rod, and a toothed wheel connected to a rotating shaft driven in rotation by the drive member. The use of rack means allows to multiply the revolutions of the drive member, or the steps in the case of an electric stepper motor, and therefore considerably increase the resolution of the positioning of the second valve means with respect to the outlet aperture, thus obtaining a precise modulation of the flow rate of combustible gas.

In accordance some embodiments, the mobile rod comprises a first body, or front body, facing toward the inlet aperture and disposed passing through the second shutter, and a second body, or rear body, which is integral with the first body, wherein the second elastic element is connected between the second shutter and an abutment portion of the first body and it is configured to act in a first direction toward the valve seating in the closed condition, and in a second opposite direction in an operating condition of the apparatus, in order to move the first body away from an operating zone of the first valve means.

The movement unit also comprises a shaped flange provided with a through hole which is suitable to cooperate on one side with the abutment portion and is configured to allow the sliding of a through segment of the second body, and a third elastic element connected between the shaped flange and a shoulder of a tubular sleeve in which the rod is housed.

On the first body, in correspondence with the front portion protruding from the second shutter, there is provided a constraint element configured to engage with the second shutter.

In accordance with another aspect of the invention, there is provided a device for mixing a first and a second gas, comprising a valve apparatus according to the invention, an air inlet, a mixture outlet and ventilation means which are drivable by means of a drive member.

In accordance with another aspect of the present invention, the air inlet and the valve apparatus are integrated in a same support body and are disposed in such a way that the air inlet is positioned on a side of the duct opposite to the outlet aperture, and the ventilation means are disposed on the side of the outlet aperture. In this way, the action of the ventilation means to suck the air creates a depression which also determines the suction of the gas along the duct and toward the outlet aperture, which mixes with the air which flows around it.

In accordance with another aspect of the present invention, a method for delivering a gas by means of a valve apparatus according to the invention comprises:

- a first opening step, in which the movement unit is displaced in a first direction in order to move the first valve means away from the inlet aperture, subsequently keeping them in the open position by means of an electric energy supply;

- a second opening step, in which the movement unit is displaced in a second direction, opposite to the first direction, in order to engage with the second valve means and move them away from the valve seating, toward the outlet aperture;

- an adjustment step, in which the movement unit varies the position of the second valve means with respect to the outlet aperture in order to vary a passage section thereof and modulate a flow rate of the gas;

- a closing step, in which the first valve means close the inlet aperture and the second valve means, through the action of the elastic means, close the valve seating. DESCRIPTION OF THE DRAWINGS

These and other aspects, characteristics and advantages of the present invention will become apparent from the following description of some embodiments, given as a non-restrictive example with reference to the attached drawings wherein:

- fig. 1 is a top section view of a valve device according to the present invention in accordance with a first embodiment in a first operating condition;

- fig. la is an enlargement of a detail of fig. 1;

- fig. 2 is a lateral view sectioned along the line II-II of fig. 1;

- figs. 3 and 4 are section views of the valve apparatus of fig. 1 in different operating conditions; - fig. 5 is an enlarged detail of fig. 4;

- fig. 6 is an enlarged detail of a valve device according to the invention in accordance with a second embodiment;

- fig. 7 is an enlarged detail of a component of the valve device;

- fig. 8 is a graph which schematically shows the modulation characteristic obtainable with a valve apparatus according to the invention;

- figs. 9 and 10 are schematic views of a mixing device in accordance with the present invention according to a top view and according to a three-dimensional view, respectively. We must clarify that in the present description the phraseology and terminology used, as well as the figures in the attached drawings also as described, have the sole function of better illustrating and explaining the present invention, their function being to provide a non-limiting example of the invention itself, since the scope of protection is defined by the claims.

To facilitate comprehension, the same reference numbers have been used, where possible, to identify identical common elements in the drawings. It is understood that elements and characteristics of one embodiment can be conveniently combined or incorporated into other embodiments without further clarifications. DESCRIPTION OF SOME EMBODIMENTS OF THE PRESENT INVENTION

With reference to fig. 1, a valve apparatus 10 for delivering gas according to the present invention comprises a duct 11 for the passage of a combustible gas extending along a longitudinal axis X and having at least an inlet aperture 12 and an outlet aperture 13. The valve apparatus 10 according to the invention can be a “stand alone” component or it can also be advantageously integrated in a mixing device 100 configured to deliver a mixture of a first gas and a second gas.

The inlet aperture 12 is preferably made on a plane orthogonal to the longitudinal axis X and puts the duct 11 in communication with a channel 14 for feeding the combustible gas.

The valve apparatus 10 comprises first valve means 15 configured to cooperate with the inlet aperture 12 to allow or prevent the flow of the combustible gas through it.

The first valve means 15 comprise a solenoid valve 16 having a first shutter 17 associated with a first elastic element 18, in the example case a helical spring, configured to stress it toward a position of closure of the inlet aperture 12.

The solenoid valve 16 comprises an electric winding 19 and a mobile core 20 which is connected to the first shutter 17 and is mobile in an integral manner therewith, which is held in the open position by the electric winding 19 when an electric current circulates in it.

The valve apparatus 10 also comprises second valve means 21 configured to cooperate both with a valve seating 22 made in the duct 11 between the inlet aperture 12 and the outlet aperture 13, and also with the outlet aperture 13 in different operating conditions.

The valve apparatus 10 also comprises elastic means 24, 36 and a movement unit 25.

In particular, as will be better described below, the second valve means 21 are configured to cooperate with the valve seating 22 through the action of the elastic means 24, 36 and with the outlet aperture through the action of the movement unit 25.

The valve seating 22 can be defined by a shoulder protruding toward the inside of the duct 11 in an intermediate position between the inlet aperture 12 and the outlet aperture 13.

Fig. 1 shows the valve apparatus 10 in a closed condition, in which the first valve means 15 close the inlet aperture 12 and the second valve means 21 are located abutting against, and closing, the valve seating 22.

The second valve means 21 comprise a second shutter 23 associated with at least a second elastic element 24, in the example case a helical spring, configured to stress the second shutter 23 toward at least one position of engagement with the valve seating 22, so as to prevent the passage of combustible gas toward the outlet aperture 13.

The second elastic element 24 acts along the longitudinal axis X. In particular, the second elastic element 24 is configured to act in a first direction DI, in the opposite sense with respect to the first elastic element 18, in order to thrust the second shutter 23 against the valve seating 22 in a closed condition of the valve apparatus 10.

The second elastic element 24 is also configured to act in a second direction D2, opposite to the first direction D 1 , to free the operating zone of the first valve means

15. In this way, the first shutter 17 can be moved toward the position of closure of the inlet aperture 12 when the solenoid valve 16 is not powered, without encountering obstacles along its travel.

The second elastic element 24 is configured to move the second valve means 22 away from the operating zone of the first valve means 15 so as to allow the first valve means 15 to close.

In accordance with some embodiments, the second shutter 23 is made of flexible and/or deformable material, suitable to flex and define a radial seal with an edge of the valve seating 22 and with an internal surface 11 a of the duct 11.

The outlet aperture 13 is made on a wall of the duct 11 and the second shutter 23 cooperates, with a lateral edge thereof, with the outlet aperture 13.

In accordance with some embodiments, the outlet aperture 13 has a diverging shape between a front part facing toward the inlet aperture 12 and a rear part opposite thereto, in such a way that, as a function of the position of the second shutter 23 with respect the outlet aperture 13, it is possible to provide a modulation of the flow rate of combustible gas, as will be better explained below.

In the embodiment shown by way of example, the outlet aperture 13 seen in plan view has a substantially triangular shape, with rounded edges, in which the apex faces the valve seating 22.

In accordance with one aspect of the invention, the valve apparatus 10 comprises a movement unit 25 provided with actuator means 26 configured to displace the movement unit 25 at least into a first operating position in which it cooperates with the first valve means 15 in order to open the inlet aperture 12, and at least into a second operating position in which it cooperates with the second valve means 21 in order to adjust their position with respect to the outlet aperture 13 so as to allow the passage of the gas through it and modulate the gas flow rate.

In particular, the actuator means 26 are configured to displace the movement unit 25, and consequently the second valve means 21, into a plurality of second operating positions, each defining a determinate passage section of the outlet aperture 13.

In accordance with some embodiments, the movement unit 25 comprises a rod 27 mobile along the longitudinal axis X and the actuator means 26 comprise a drive member 28 and transmission members 29 configured to transfer motion from the drive member 28 to the rod 27.

The drive member 28 is preferably an electric motor of the stepper type.

The rod 27 is mobile inside a tubular sleeve 30 which is associated at one end with the duct 11 and is preferably closed at one end. In accordance with one aspect of the invention, the rod 27 comprises a first body 31, or front body, facing toward the inlet aperture 12, and a second body 32, or rear body, connected to the first body 31 in an integral manner.

The first body 31 is disposed passing through the second shutter 23 in such a way that a front portion 33 is always disposed protruding from the second shutter 23, and it is configured to move relative thereto in a first DI or a second D2 direction when subjected to the action of the drive member 28.

On the first body 31, in correspondence with the front portion 33, there is provided a constraint element 34, in the example case a washer, configured to engage with the second shutter 23.

The second elastic element 24 is connected between the second shutter 23 and an abutment portion 35 of the first body 31.

In this way, when the shutter 23 abuts against the valve seating 22, the second elastic element 24 can extend in the second direction D2 in order to move the first body 31 away from the operating zone of the first valve means 15.

On the other hand, when the shutter 23 is in one of the plurality of second operating positions, and therefore distanced from the valve seating 22, the second elastic element 24 can stress the second shutter 23 in the first direction DI taking it in abutment against the valve seating 22 when the drive member 28 is not active. The second elastic element 24 can be disposed substantially coaxial to the first body 31.

In accordance with one aspect of the present invention, the movement unit 25 comprises a third elastic element 36 associated with the rod 27 and configured to move it in the first direction DI when the drive member 28 is not in operation, so as to contribute to returning the second shutter 23 in abutment against the valve seating 22.

In particular, the third elastic element 36 can compress and pre-load when the rod 27 is moved in the second direction D2 by the actuator means 26 and once again extend in the first direction DI when the actuator means 26 are not active.

Between the first 31 and the second 32 body there is provided an uncoupling element 49 configured to allow a segment of the rod 27 to slide therein and uncouple the second 24 and the third 36 elastic element from each other, so that they can operate autonomously and independently of each other. In accordance with some embodiments, the uncoupling element 49 can comprise, or be made in the form of, a shaped flange 37 (figs. 1-5) or a washer 60 (fig- 6).

The shaped flange 37 is provided with a through hole 38 through which a through segment 42 of the second body 32 delimited by an abutment element 43 can pass, in this specific case a portion with larger sizes than the through hole 38.

The shaped flange 37 can have a cup-like shape, with a cavity facing in the first direction DI, suitable to house the abutment portion 35, wherein a peripheral portion of the bottom wall around the through hole 38 acts as an abutment and end of travel for the abutment portion 35.

A protruding end 44 of the first body 31 , which extends beyond the abutment portion 35, can also transit in the through hole 38, the protruding end 44 engaging, in the example case by screwing, in a seating of the second body 32. Obviously, different engagement members can also be provided, for example of the bayonet or snap-in type.

In particular, the third elastic element 36 is connected with one end to the shaped flange 37 and with the opposite end to a shoulder 41 made in the tubular sleeve 30. The third elastic element 36 can be disposed substantially coaxial to the second body 32.

The duct 11 can have an abutment seating 39 in which the shaped flange 37 can be positioned abutting. The abutment seating 39 is disposed downstream of the outlet aperture 13 in the second direction D2.

In particular, the duct 11 can have a passage section which increases from the abutment seating 39 toward the end cooperating with the tubular sleeve 30.

In this way, the second 24 and the third 36 elastic element are constrained to, and act on, different components which have at least one degree of freedom between them.

The function of the third elastic element 36 is in fact to move the shaped flange 37, and consequently the rod 27, in the first direction D 1.

In particular, the third elastic element 36, preloaded by the movement of the rod 27 in the second direction D2, elongates in the first direction DI until the shaped flange 37 is taken back against the abutment seating 39, while the abutment portion 35 acts on the second elastic element 24, at least partly compressing it, so as to allow the accumulation therein of elastic energy sufficient to move the second shutter 23 until it is taken in abutment against the valve seating 22.

In accordance with some embodiments, the third elastic element 36 can possibly also act in the second direction D2, when the second shutter 23 abuts against the valve seating 22, so as to contribute to moving the first body 31 away from the operating zone of the first valve means 15.

According to possible solutions, it can be provided that the rod 27 and the tubular sleeve 30 are provided with respective end-of- travel members 40 configured to cooperate with each other and stop the travel of the rod 27 in the first direction DI, for example a pair of opposing teeth.

In accordance with another aspect of the present invention, the transmission members 29 are of the rack type and comprise a toothed portion 45 made on the rod 27, in particular on the second body 32, and a toothed wheel 46 connected to a rotating shaft 47 driven in rotation by the drive member 28.

When the drive member 28 is switched off, the toothed wheel 31 can be advantageously idle, allowing the movement of the rod 27 due to the effect of the elastic force of the second 24 and of the third 36 elastic element.

The use of rack transmission members 29 allows to multiply the steps of the drive member 28 and therefore considerably increase the resolution of the positioning of the second valve means 21 with respect to the outlet aperture 13, so as to obtain a precise modulation of the flow rate of combustible gas.

By way of example, two revolutions of the drive member 28 can correspond to six different teeth of the toothed portion 45, therefore it is possible to increase the resolution by up to three times compared to solutions which provide couplings of the screw-nut type, or in any case without rack transmission members.

The high resolution in defining the position of the second valve means 21 makes the valve apparatus 10 suitable for use not only as a delivery and safety valve, but also as a gas quantity regulation and modulation valve. That is to say that with this valve apparatus 10 it is possible to have not only the open and closed conditions but also a plurality of different operating conditions, each associated with a determinate passage section of the outlet aperture 13.

Thanks to the cooperation between the second 24 and the third 36 elastic element and the abutment means 35, 39, 43, it is possible to automatically return the valve apparatus 10 to a neutral position without the need to count the steps, that is, the revolutions of the drive member 28 in one or the other sense, and at the same time allow the toothed wheel 46 to rotate idly.

As will be better explained below, in fact, the elastic elements 24, 36 accumulate elastic force when the drive member 28 moves the rod 27 in one or the other direction DI, D2, and this accumulated elastic force allows to return the valve apparatus 10 in a closed condition, and the various components in a neutral, stable and repeatable position, allowing to greatly simplify the control of the valve apparatus 10.

According to further embodiments, described with reference to fig. 5, an annular gasket 48 is provided on the second body 32, in the example case an O-ring, configured both to guarantee the seal of the valve apparatus 10 and also to check this seal before installation. The annular gasket 48, in a completely open condition of the valve apparatus 10, is configured to cooperate with an internal wall of the tubular sleeve 30 downstream of the shoulder 41, thus preventing any gas leakages.

Fig. 6 shows a detail of a valve apparatus 10 according to a variant. The components that are shared with the embodiment of figs. 1-5 are indicated with the same reference numbers and will not be described further.

This variant differs from the previous one in that instead of the shaped flange there is a washer 60, which is provided with a through hole 61 through which the through segment 42 of the second body 32 can pass.

Preferably, on the side facing toward the second body 32, the washer 60 has a substantially cylindrical protruding portion 62, around which an end of the third elastic element 36 is positioned in such a way as to guarantee its centering and prevent one of its coils from getting stuck on the abutment seating 39.

The protruding portion 62 can extend in continuity with the through hole 61 so that the washer 60 has a substantially L-shaped section on each side of the through hole 61.

The variant of fig. 6 also differs in that in this case the annular gasket 48 is no longer present, but a lip seal 63 is provided, which can be disposed on, or integrated with, the second shutter 23. The lip seal 63, in a condition in which the valve apparatus 10 is completely open, can extend radially and is located abutting against a sealing seating 64 made on the internal wall of the duct 11 or on a component 65 inserted in the duct 11 itself.

It will be clear to a person of skill in the art that these variants of characteristics can be combined differently in other embodiments, not shown. Hereafter, with reference to figs. 2-4, we will describe the operation of the valve apparatus 10, which corresponds to a method for delivering the gas according to the present invention.

Fig. 2 shows the valve apparatus 10 in a completely closed condition, in which the first shutter 17 closes the inlet aperture 12 stressed by the first elastic element 18 and the second shutter 23 is kept abutting against the valve seating 22 by the second elastic element 24.

In this completely closed condition, the gas coming from the gas feeding channel 14 is blocked upstream of the first shutter 17. In a first step of opening the valve apparatus 10, the movement unit 25 is displaced in the first direction DI so that the first body 31, sliding through the second shutter 23, comes into contact with the first shutter 17 and thrusts the latter away from the inlet aperture 12 until the mobile core 20 reaches an end-of-travel position. The second elastic element 24 is compressed between the second shutter 22 and the abutment portion 35.

The movement of the rod 27 in the first direction D 1 also involves the passage of the through segment 42 in the through hole 38 while the shaped flange 37 remains in abutment against the abutment seating 39.

In this first opening step, an electric current is fed into the electric winding 19 in order to keep the mobile core 20 in the end-of-travel position so that the first shutter 17 remains distanced from the inlet aperture.

The electric current is advantageously supplied by means of suitable power supply means, not shown, suitable to guarantee the start-up step.

Thanks to the fact that the first shutter 17 and the mobile core 20 are moved by means of the movement unit 25, it is possible to keep the sizes of the electric winding 19 and of the mobile core 20 small, since the electromagnetic force necessary to hold the mobile core 20 in position is much smaller than that required to displace it.

When the drive member 28 ceases to be driven, the third elastic element 36 returns the first body 31, and therefore the rod 27, to the rest position, outside the operating zone of the first shutter 17, so that, in the absence of power supply to the electric winding 19, the first shutter 17 can return to the closed condition.

In a second step of opening the valve apparatus 10, the drive member 28 is driven in the opposite sense in order to move the rod 27 in the second direction D2, making the first body 31 slide through the second shutter 23 so that the constraint element 34 attached to the first body 31 engages with the second shutter 23 and drags the latter along with it. As can be seen from fig. 1, which corresponds to the condition of complete closure of the valve apparatus 10 and the neutral position of the various components, the toothed wheel is engaged with the third and fourth tooth from the right, so that, before the rod 27 reaches an end-of-travel position against the closed end of the tubular sleeve 30, at least eight other intermediate positions, or even more, can be provided.

In this way, in the second opening step, the second valve means 21 allow to modulate the gas flow rate since, as a function of the position of the second shutter 23 with respect to the outlet aperture 13, the passage section of the latter and, consequently, the gas flow rate and therefore the quantity of combustible gas fed in a unit of time, is modified.

In particular, the modulation of the gas flow rate occurs through the movement of the second shutter 23, which has a substantially cylindrical shape, with respect to the outlet aperture 13, which has a particular shape as shown in fig. 7 and is made on a cylindrical surface of the duct 11. The outlet aperture 13 in the plan view of fig. 7 has a substantially rectilinear rear edge 13a, orthogonal to the longitudinal axis X, an apex 13b opposite the rear edge 13a and two lateral edges 13c, 13d which connect the rear edge 13a to the apex 13b. In the view of fig. 7, the lateral edges 13c, 13d are symmetrical to each other and have a curved development. The profile of the outlet aperture 13, and in particular of the lateral edges 13c, 13d, has been designed in such a way as to guarantee, for a wide range of flow rates, an approximately constant percentage flow rate variation for each minimum displacement of the second shutter 23. In particular, the curved development of the outlet aperture 13 can be defined by an exponential relation:

in which x is the travel of the second shutter 23 in the direction XI indicated in fig. 7 and y is the width of the outlet aperture 13 in the direction Y indicated in fig.

7. In the graph in fig. 8, the dash-dot line indicates the trend of the gas flow rate, and the dashed line indicates the percentage flow rate variation for each step of the motor as a function of the open section of the outlet aperture 13 expressed in percentage terms. As can be seen, it is possible to obtain a precise modulation of the amount of gas.

The method according to the invention also comprises a step of automatic closure of the valve apparatus 10, for example at the end of the delivery of gas or in the event of malfunctions which cause a shutdown of the power supply means which supply electric energy to the first valve means 15 and to the actuator means

26.

In this closing step, the first shutter 17, through the action of the first elastic element 18, closes the inlet aperture 12 and the second shutter 23, through the action of the second elastic element 24, abuts against the valve seating 22, thus preventing the flow of gas through it.

Figs. 9 and 10 show a mixing device 100 according to the invention which comprises, integrated therein, a valve apparatus 10.

The mixing device 100 comprises an air inlet 51 and a mixture outlet 52.

The air inlet 51 can advantageously be made in a support body 50 in which the valve apparatus 10 is disposed made through.

The air inlet 51 can comprise a feed channel 53 preferably having a tapered section between an inlet aperture 54 and a passage aperture 55.

In accordance with one aspect of the invention, the inlet aperture 54 is disposed substantially aligned with the outlet aperture 13 on the opposite side of the duct 11 with respect to it.

The mixing device 100 also comprises ventilation means 56, in this specific case an impeller 57 driven by a drive member 58, which are disposed, during use, aligned with the outlet aperture 13 on the opposite side of the inlet aperture.

The impeller 57 can be disposed inside a mixing chamber 59, which can be at least partly made in the support body 50.

Advantageously, when the ventilation means 56 are in operation, they create a depression which also causes the gas to be sucked in through the outlet aperture 13, so that in correspondence with the impeller 57 the air and the gas can mix before reaching the mixture outlet 52.

As disclosed above, it is possible to quickly and easily change the flow rate of gas at outlet, and consequently the “lambda” ratio between air and gas, simply by moving the second shutter 23 in the first DI or in the second D2 direction so as to decrease or increase, respectively, the passage section of the outlet aperture 13.

It is clear that modifications and/or additions of parts or steps may be made to the valve apparatus 10 and to the corresponding method as described heretofore, without departing from the field and scope of the present invention, as defined by the claims. It is also clear that, although the present invention has been described with reference to some specific examples, a person of skill in the art will be able to achieve other equivalent forms of valve apparatus 10 and method, having the characteristics as set forth in the claims and hence all coming within the field of protection defined thereby. In the following claims, the sole purpose of the references in brackets is to facilitate their reading and they must not be considered as restrictive factors with regard to the field of protection defined by such claims.

Claims

1. Valve apparatus (10) for delivering gas comprising a duct (11) for the passage of a gas extending along a longitudinal axis (X) and having an inlet aperture (12) and an outlet aperture (13) and first valve means (15) which are configured to cooperate with said inlet aperture (12) to allow or prevent the flow of said gas, characterized in that it comprises second valve means (21), elastic means (24, 36) and a movement unit (25), said valve means (21) being configured to cooperate both with a valve seating (22) in order to close said valve apparatus (10), through the action of said elastic means (24, 36), and also with said outlet aperture (13) in order to adjust a passage section of said outlet aperture (13) through the action of said movement unit (25).

2. Valve apparatus (10) as in claim 1, characterized in that said second valve means (21) are associated both with said elastic means (24, 36) and also with said movement unit (25) and in a closed configuration of said apparatus (10) are subjected to the action of said elastic means (24, 36) while in an operating configuration of said apparatus (10) they are subjected to said movement unit (25).

3. Valve apparatus (10) as in claim 1 or 2, characterized in that said first valve means (15) comprise a solenoid valve (16) having a first shutter (17) associated with a first elastic element (18), and said second valve means (21) comprise a second shutter (23) associated with a second elastic element (24), wherein said first and second elastic elements (18, 24) act along said longitudinal axis (X) in opposite directions (D2, DI) in order to close respectively the inlet aperture (12) and the valve seating (22) in a closed condition of said valve apparatus (10).

4. Valve apparatus (10) as in any claim from 1 to 3, characterized in that said outlet aperture (13) is made on a lateral wall of said duct (11) and said second shutter (23), made of flexible and/or deformable material, suitable to flex and define a radial seal with said duct (11), has a lateral edge thereof cooperating with said outlet aperture (13) in order to adjust a passage section thereof.

5. Valve apparatus (10) as in one or the other of the previous claims, characterized in that said outlet aperture (13) has a diverging shape between a front part facing toward said inlet aperture (12) and an opposite rear part.

6. Valve apparatus (10) as in one or the other of the previous claims, characterized in that said movement unit (25) is configured to cooperate with both of said valve means (15, 21), and said valve apparatus (10) comprises actuator means (26) configured to displace said movement unit (25) at least into a first operating position in which it cooperates with said first valve means (15) in order to open said inlet aperture (12), and into a plurality of second operating positions in which it cooperates with said second valve means (21) in order to adjust their position with respect to said outlet aperture (13), defining different operating conditions.

7. Valve apparatus (10) as in claim 6, characterized in that said movement unit (25) comprises a rod (27) which is mobile along said longitudinal axis (X), and said actuator means (26) comprise a drive member (28) and rack transmission members (29) configured to transfer motion from said drive member (28) to said rod (27) and multiply the revolutions of said drive member (28).

8. Valve apparatus (10) as in claims 3 and 7, characterized in that said rod (27) comprises a first body (31) disposed passing through said second shutter (23) and a second body (32) integral with said first body (31), and said second elastic element (24) is connected between said second shutter (23) and an abutment portion (35) of said first body (31), and it is configured to act in a first direction (DI) in order to thrust said second shutter (23) toward said valve seating (22) in said closed condition, and to act in a second direction (D2) in order to move said first body (31) away from an operating zone of said first valve means (15) in an operating condition of said valve apparatus (10).

9. Valve apparatus (10) as in claim 8, characterized in that said movement unit (25) comprises a shaped flange (37) or a washer (60) configured to allow the sliding of a through segment (42) of said second body (32), and a third elastic element (36) is connected between said shaped flange (37) or said washer (60) and a shoulder (41) provided on a tubular sleeve (30) and is configured to move said rod (27) in a second direction (D2) opposite to said first direction (DI).

10. Valve apparatus (10) as in claim 9, characterized in that on said second body (32) there is provided an annular gasket (48), configured both to guarantee the seal of said valve apparatus (10) and also to check said seal before installation, wherein said annular gasket (48), in a completely open condition of said valve apparatus (10), is configured to cooperate with an internal wall of said tubular sleeve (30) downstream of said shoulder (41).

11. Device (100) for mixing a first and a second gas, characterized in that it comprises a valve apparatus (10) as in one or the other of the previous claims, an air inlet (51), a mixture outlet (52) and ventilation means (56) which are drivable by means of a drive member (58).

12. Mixing device (100) as in claim 11, characterized in that said air inlet (51) and said valve apparatus (10) are integrated in a same support body (50), wherein said air inlet (51) is positioned on one side of said duct (11) opposite to said outlet aperture (13), and said ventilation means (56) are disposed on the side of said outlet aperture (13).

13. Method for delivering a gas by means of a valve apparatus (10) as in one or the other of claims from 1 to 10, characterized in that it comprises:

- a first opening step, in which said movement unit (25) is displaced in a first direction (DI) in order to move said first valve means (15) away from said inlet aperture (12) and said valve means (15) are subsequently kept in the open position by means of electric energy supply members;

- a second opening step, in which said movement unit (25) is displaced in a second direction (D2), opposite to said first direction (DI), in order to engage with said second valve means (21) and move them away from said valve seating (22) toward said outlet aperture (13); - an adjustment step, in which said movement unit (25) varies the position of said second valve means (21) with respect to said outlet aperture (13) in order to vary a passage section thereof and modulate a flow rate of said gas;

- a closing step, in which said first valve means (15) close said inlet aperture (12) and said second valve means (21), through the action of said elastic means (24, 36), close said valve seating (22).