The subject-matter of the present invention is a compensation valve according to the preamble of the main claim .

It is known that in environments closed or delimited by walls having a pressure different from that of the external environment there is a need for using at least one compensation valve installed on at least one wall thereof and suitable for putting the inside of such delimited environments in communication with the external environment in order to balance pressure; the external environment is possibly at the atmospheric pressure. Specifically, an environment of the type indicated above is a controlled atmosphere room or the inside of a refrigerating room or a refrigerated cabinet or a simple residential room the pressure of which should be automatically controlled with respect the external environment.

In the cases mentioned above it is known the use of a compensation valve in at least one even horizontal wall (for instance a ceiling) of the delimited environment, suitable for balancing the pressure existing in such environment (for instance a refrigerating room) with the external pressure (for instance the atmospheric pressure) . Since the general practice is to drill round holes in the wall in order to make the installation works simpler, the known compensation valves usually feature a hollow cylindrical body, generally closed by a grid on the side facing the environment external to the refrigerating room and completely open on the side facing the latter; such body (arranged with its axis orthogonal to the wall of the cell) includes, internally thereto, a passageway intercepted by a valve element generally and usually consisting of a flapper or panel movable with respect to the opening of such passageway. Since the latter has a cylindrical shape and a circular cross-section, the panel cannot have the shape of a circle so as to completely close/open such passageway and simultaneously be capable of moving in order to make its opening possible. Consequently, the practice is known of realizing such panel in a polygonal (for instance square) shape and to insert it into a frame located inside said passageway, presenting a (circular) portion integral with the wall of the passageway and an opening having a shape mating that of the panel; the latter is arranged, upon closing said opening, in such a way as to be perpendicular to the longitudinal axis of the passageway and parallel to the area where such opening is located. In this way, the panel can move with respect to the frame and within the passageway by rotating about one or several hinges which connect it to the frame and make it possible to open the passageway as well as to close it.

Such solution presents a number of drawbacks and in particular it requires that the movable panel, internally to the passageway, be located vertical or, as referred to the arrangement of the compensation valve which has the longitudinal axis of its own passageway orthogonal to the wall of the refrigerating cell, orthogonal to such axis and parallel to such wall. This in order to make a correct displacement of the panel itself possible.

Such positioning is necessary to make it possible an effective exploitation of the valve, but on the other hand it is restrictive with respect to the installation of the valve into the wall, an operation that requires a special attention in order to arrange the valve in such a way that the movable panel be correctly closed whenever no air flow shall exist between different environments. This closed position is also facilitated by the presence of a return spring acting onto the movable panel, a spring that might yield over time and lose its capability of offering any longer the strength necessary to held the panel closed when desired .

Another solution is also known wherein the passageway is split into two parallel channels each closed by a half- circle (also operating as an on-off control member for its respective channel) movable about a diameter of the passageway itself. In this case too, however, there is a need for arranging the valve in the hole of the wall in such a way that the half-circles be reliably closed whenever there is no air flow between the environments.

Furthermore, in this case too there is a need for using a return member for said half-circle suitable for holding it closed whenever there is no air flow between the environments. Therefore, the problems of duration of effectiveness of the spring onto its corresponding on-off control member over time still exist.

In addition, the known solutions are difficult to implement (because of the presence of one or several spring-operated on-off control members), have problems of efficiency over time, and consequently feature high costs.

Another example of a pressure compensation valve of a known type is disclosed in the Unites States patent application no. US 2008/0128033. This document concerns a valve capable of selectively lowering the pressure inside an environment whenever the pressure exceeds a predetermined value. The valve disclosed in US 2008/0128033 makes also it possible to modify the set pressure value at which the valve opens to put the environment in communication to the outside thus making the pressure of the environment decrease. This valve comprises a body and a flapper which is rotationally mounted on the body and is movable between a closed position, in which it seals the flow channel, and an open position, in which the flapper enable the flow to pass. The flapper is held in the closed position thanks to the presence of a magnet incorporated in the flapper which engages a magnetic element associated with the valve body in a position facing the magnet. The positon of the magnetic element can be modified in order to vary the distance (air gap) between it and the magnet so as to modify the electromagnetic force that holds the flapper closed. In this way, it is consequently possible to vary the pressure at which the valve opens, i.e. the pressure of the fluid necessary to overcome the electromagnetic force that keeps the flapper in the closed position.

A drawback of this valve is in that the positions of the magnet and of the magnetic element, which are placed at the highest distance from the axis of rotation about which the flapper is hinged, do not guarantee a reliable operation because in some mounting configurations of the valve the electromagnetic force is not capable of holding the flapper in the closed position at the specified pressure. In other words, the orientation of the valve in the space might affect its correct operation. For instance, if the valve is mounted on a horizontal wall, then the weight force (due to its own weight of the flaps) might sum to the force exerted by the pressurized fluid onto the flapper and cause the electromagnetic force not to be capable any longer of closing the flapper at the set pressure.

An object of the present invention is therefore to offer a compensation valve that is improved with respect to the known solutions.

Specifically, an object of the present invention is to offer a compensation valve that makes it possible an optimum and safe closing of the passageway connecting the inside of the variable pressure environment to the external environment irrespective of how is it mounted in a wall of the delimited environment.

A further object of the present invention is to offer a compensation valve that retains its own operating efficiency unchanged over time.

A further object of the invention is to provide a compensation valve of the mentioned type that does not include any return springs for its movable parts and consequently is simpler to manufacture than known valves and has lower costs as compared thereto.

These objects and others that will be apparent to those skilled in this sector are achieved by a compensation valve according to the attached claims.

For a better understanding of the present invention, the following drawings are attached for merely explanatory, not limitative, purposes, wherein:

figure 1 shows an exploded perspective view of a compensation valve according to the invention;

figure 2 shows an exploded perspective view of a member of the compensation valve of figure 1 ;

figure 3 shows a front view of the compensation valve of figure 1 ;

figure 4 shows a cross-sectional view of the valve of figure 1 according to the trace 4-4 of figure 3 ;

figure 5 shows a cross-sectional view according to the trace 5-5 of figure 3; and

figure 6 shows a side view of the assembled valve of figure 1 in a position of use.

With reference to the mentioned figures, a compensation valve is generally referred to by the numeral 1 and comprises a hollow tubular body 2 having end flanges 3 and 4 on which covers 5 and 6 respectively are suitable for being placed (for merely aesthetic purposes) . Such valve body 2 is suitable for being inserted in a through hole 10 obtained in a wall 11 which separates an environment 13, closed and delimited by its own walls, from an external environment 14. The delimited environment 13 is an environment wherein there is or at least there might be a pressure different from that of the external environment (14) which might be at the atmospheric pressure.

For merely explanatory purposes, the substantially controlled (but variable) pressure delimited environment might be a refrigerating cell, a refrigerated cabinet, a controlled environment room or even a room of a house having openings (windows or doors) on which highly airtight door or window frames are placed. In such environments the internal pressure might be different from the atmospheric one and such difference is autonomously compensated for by way of the valve 1 which allows a controlled air flow between the delimited and external environments thus allowing to regulate and make said pressure uniform.

More specifically, the valve body 2 is preferably defined by a first and second cylindrical portions 16 and 17, which are tubular and hollow and having, at a first end 18 thereof, flanges 3 and 4. At such end 18 every portion 16 and 17 presents an opening 20 on which there is placed a grid 21. In the flanges 3 and 4 there are provided holes 22 suitable for receiving binding members (for instance screws) binding the body 2 to the opposed faces 11A and 11B of the wall 11 facing the environments 13 and 14.

Preferably the cylindrical portions 16 and 17 telescopically couple to each other and have their own second ends 23 and 24 suitable for reciprocally interpenetrating: in particular, the end 23 of the portion 16 penetrates the end 24 of the portion 17. This allows to adjust the dimension of the body 2 as a function of the thickness of the wall 11 (or distance between its faces 11A and 11B) . Advantageously the cylindrical portion 17, at least internally, is slightly conical and it widens as moving from the first end 18 to the second end 24.

Within the tubular body 2 there is a valve member 30 externally cylindrical-shaped and having an outer face 33 and an inner face 34. Such member 30 has opposed ends 30A and 30B having seats 27 for a seal ring (not shown) suitable for co-operating by interference with an inner surface 28 of the first cylindrical portion 16. Such cooperation holds the member 30 in position within this first portion 16. The inner face features two spaced away arched ridges 36 and 37 and an inner longitudinal wall 38 (preferably having a length equal to half circle), slightly tilted with respect to the longitudinal axis W of the member 30. Such wall determines inside the member 30 two substantially parallel channels 40 and 41 suitable for being closed, at opposed ends, by on-off control members or flappers 42. Every flapper or member 42 is substantially half-circle shaped and closes a corresponding channel 40 and 41 of a similar shape.

Every on-off control member 42 is hinged to the valve member 30 so as to be capable of rotating about an axis of rotation that is arranged transversally with respect to the longitudinal axis W of the member 30.

More specifically, every on-off control member 42 is hinged at a first end 45 thereof and at a second end 48 to the inner face 34 of the member 30 via a projecting pivot 46 inserted into a corresponding seat 47 obtained in such face or of a bowl plug 47A inserted in such seat. To said first end 45 and to the second end 48 (i.e. to the ends of the diameter of the half-circle defining the shape of the member 42) an arch 49 is connected suitable for operating as a compensator for the movement of the member 42 about said pivot 46. The arch 49 and the member 42 form one piece .

In addition, at the second end 48 there is present a seat 50 for a permanent magnet (containing ferrites or neodymium or iron cobalt) 51 suitable for co-operating with a magnetic body 53 associated with the member 30 and inserted into a seat 54 thereof. Such magnetic body 53 is either a permanent magnet or an electromagnet and its function is to attract, by way of the magnetic force only, the permanent magnet 51 of the member 42 whenever the latter rotates about the pivot 46 being pushed by the air flowing through its respective channel 40 or 41, thus opening a communication between the environments 13 and 14 via said channel. The co-operation of such magnetic elements 51 and 53 is suitable for holding the channel 40 or 41 on which every on-off control member 42 is placed, closed.

Obviously, in order to get this action, the magnetic elements 51 and 53 shall have a correct arrangement of their polarities in such a way that the magnets reciprocally attract rather than reciprocally repelling.

Note that the seats 50 and 54, intended to receive the permanent magnet 51 and the magnetic body 53 respectively, are in proximity to either pivot 46, i.e. substantially on the axis of rotation of the on-off control member 42. This causes the magnetic elements 51 and 53 to be always in proximity to each other, irrespective of the position of the on-off control member 42. An advantage of this arrangement of the magnetic elements 51 and 53 is in that the electromagnetic force always holds such an intensity as to guarantee the closing of the channels 40 and 41 by the on-off control member 42. As a matter of fact, whatever the position of the on-off control member 42 is, the magnetic elements 51 and 53 are at a reduced distance from each other, so that the return electromagnetic force always holds a high intensity, capable of guaranteeing the closing of the channels 40, 41 by the on-off control member 42.

The on-off control members or flappers 42 move in directions of rotation about the pivots 46 that are contrary to each other. In this way, only one of said channels 40 and 41 opens, when necessary, as a function of the difference of pressure existing between the environments 13 and 14. When closed, the members 42 lay against a corresponding ridge 36 or 37 of the inner face 33 of the valve member 30.

On the outer face 33 of the valve member 30 there are ribs 57 between which there are arranged the turns of a spiral electrical resistor 58 suitable for heating the member 30 and preventing ice from built-up as air flows therethrough (when the compensation valve 1 is used in association with a refrigerating cell or a refrigerated cabinet) . Such resistor has ends 59 that are received in a seat 60 of the first cylindrical portion 16 (in the embodiment here described) where they are enveloped by a seal ring 61 and pressed by a usual compression gland 62 co-operating with such seat 60. Obviously, the electrical resistor might even be of another type and shape, for instance a sheet resistor.

Thanks to the invention and to the co-operation between the bodies or magnetic elements 51 and 53 described above, every on-off control member is normally brought to the closed position of its corresponding channel 40 or 41 irrespective of the spatial orientation (vertical, horizontal, tilted) of such member with respect to the axis K of the hole 10 in which the valve 1 is placed. Consequently, this allows a simpler and faster mounting of the valve into such hole.

In addition, thanks to the attraction magnetic force between the bodies or elements 51 and 53, every on-off control member is suitable for closing its own channel 40 or 41 without any need for using springs that might yield over time and consequently lose their effectiveness.

The force necessary to close every channel 40 and 41 by way of rotation of the flappers 42 is not affected by the orientation of the valve internally to the hole 10 where the valve is inserted. Such important advantage is also due to the geometry of every flapper 42 whose centre of mass (or centre of gravity) lays on the axis of rotation thereof (which joins the pivots 46 to each other) .

Furthermore, the valve according to the invention features a very reliable operation thanks to the position of the magnetic elements 51 and 53 in proximity to the axis of rotation of the on-off control member 42. This makes the magnetic elements 51 and 53 always be at a reduced distance from each other irrespective of the position of the on-off control member 42 so that the electromagnetic force therebetween always maintains an appropriate intensity to guarantee the closing of the on-off control member 42 regardless of the orientations of the valve 1 in the space (i.e. irrespective of whether it is mounted on a horizontal, vertical, or oblique wall) .

Note that in some applications, for instance those described above wherein the valve separates a refrigerating room from an external environment, it is very important that the valve 1 does not remain open because, in this event, ice might build-up and obstruct the valve and prevent the correct operation thereof. Everybody can consequently appreciate the importance of having a valve featuring an extremely reliable operation.

In addition, the valve here described is easy to implement. Furthermore, the above mentioned magnetic force necessary for the attraction feature can be calibrated by using magnets 51 and 53 (or equivalent electrical members) having appropriate dimensions as a function of the dimensions of every on-off control member 42. Thanks to this dimensioning it is also possible to set an air pressure threshold beyond which the member 42 opens its respective channel 40 and 41; this also allows to get a constant value between the air flowrate/air pressure of the channel and the moment when the member 42 moves thus opening the channel and releasing the air flow between the environments 13 and 14.

Finally, the arch 49 operating as a compensator is also sized as a function of the geometry of the on-off control member to hold the centre of mass on the axis of rotation thereof.

A preferred embodiment of the invention has been described. However, others are possible: for instance, one channel only might be provided within the valve member 30 on which one (only) corresponding on-off control member is placed; such solution might be convenient whenever it is required to have an air flow between the environments 13 and 14 that is always unidirectional. These solutions are also to be considered to fall in the scope of the invention as defined by the attached claims.