DESCRIPTION

The present patent concerns expansion tanks, and more specifically it concerns a new expansion tank which is compact and with no membrane.

Expansion tanks are hydraulic components commonly present in boilers for domestic heating, in heating systems and in water supply systems, in which they serve the function of compensating for the variations in volume produced by the variations in the temperature of the fluid used in the circuit, thus avoiding dangerous pressure increases in the circuit itself, which otherwise would be absorbed by the pipes and other components of the system.

Expansion tanks are commonly present also in pumping systems and lifting systems, in which they serve the function of accumulating the fluid of the circuit and allowing said fluid to return to the circuit itself.

Expansion tanks also serve to protect systems from sudden pressure changes due to instant flow interruptions with the consequent generation and propagation of water hammering.

Expansion tanks are known which comprise two semi rigid cap-shaped half shells, usually made of a metallic material, opposing and joined to each other in such a way as to form a closed casing with substantially circular cross section.

Inside the tank there is a membrane which divides the internal space into two compartments intended to respectively contain the compressible gas that compensates for the increase in the volume of the fluid contained in the system and the non-compressible fluid subject to volume variations.

The half shell intended to contain the system fluid is provided with a connection pipe which communicates with the respective inner compartment and serves for connecting the compartment itself to the hydraulic circuit.

The other half shell, instead, is provided with a valve holder carrying a preload valve which is suited to be used to adjust the gas pressure. Said valve is suited to open in case of overpressure in the compartment containing the compensation gas.

Said half shells making up the expansion tanks of the known type are generally made of a metallic material, typically stainless steel.

The inside of the expansion tank, and more specifically the inside of the compartment into which the liquid flows, is subject to the corrosive effect of the water or of other fluids circulating therein.

In order to overcome this drawback, expansion tanks have been developed which are provided with a counter cap inserted and applied inside said second half shell, said counter cap being made of a thermoplastic material, that is, a material resistant to the corrosive effects of fluids.

Said counter cap is made in such a way that it adheres to the internal surface of said second half shell and is provided with an opening which is identical to and aligned with the opening provided in the connection pipe that connects the second half shell with the system.

Said counter cap is generally tightly constrained to the half shell at the level of said connection pipe and inside the half shell, for example by means of a metallic ring.

Analogously, corrosion resistant connection pipes are known, consisting of a pipe, the inside of which is threaded at least for its section facing towards the inside of said second half shell, and of an internal sealing flange made of a thermoplastic material, mounted inside said counter cap and suited to be screwed into said pipe, so as to protect the pipe itself.

More specifically, said internal sealing flange in turn comprises an externally threaded tubular section which is suited to be screwed on the internal thread of said pipe for connection to the system, and a flat ring which is orthogonal to the axis of said threaded tubular section and suited to adhere to the internal counter cap of said second half shell.

Tightly screwing said internal flange, as well as using suitable gaskets, prevents the liquid and the air circulating in the system from leaking between the second half shell and the internal counter cap or between the internal flange and the pipe for connection to the system.

The expansion tanks made as described above are difficult to construct and to assemble, and furthermore over time stresses and prolonged use may affect the tightness of the connection between the parts.

A further drawback posed by the expansion tanks of the known type lies in that they have considerable overall dimensions, due both to their size, which depends on the type of system in which they are installed, and to their substantially circular shape or in any case to their shape with circular cross section.

These expansion tanks, in fact, must be installed in specifically prepared spaces, for example in the boiler or another part of the system.

In order to overcome the drawbacks described above, a new type of expansion tank, which is compact and has no membrane, has been designed and constructed.

The main object of the present invention is to provide an expansion tank that is more compact compared to the expansion tanks with half shells of the known type, especially because the shape of the new expansion tank is substantially parallelepiped and furthermore adaptable according to the space available for its installation.

It is another object of the present invention to simplify the procedures required for the production and assembly of the new expansion tank. The new expansion tank, in fact, has no membrane at all, and furthermore it is made up of parts that do not require the application of any counter cap.

In addition to the above, the new expansion tank resolves all the problems described above in relation to the assembly of hydraulic connection pipes.

These and other direct and complementary objects are achieved by the new expansion tank, which among its main parts comprises:

a battery of pipes, consisting of two or more pipes open at both ends, arranged side by side and parallel to one another;

a lower flange, hereinafter referred to as water side flange, in turn comprising a substantially flat plate, wherein one side, or outer side, comprises at least one hole for connection with the hydraulic system in which pressure and volume variations need to be compensated for, while the opposite inner side, which faces towards said battery, comprises a plurality of holes connected to each one of the lower open ends of each one of said pipes, and wherein one or more channels obtained in said plate place said connection hole in communication with all of said holes provided in the inner side, in such a way that the water can flow through said connection hole, said channels and said holes between the hydraulic system and the inside of each one of said pipes;

an upper flange, or gas side flange, in turn comprising a substantially flat plate, wherein one side, or outer side, comprises a hole for the installation of a pressure relief valve, while the opposite inner side, which faces towards the battery, comprises a plurality of holes connected to each one of said upper open ends of said pipes, and wherein one or more channels obtained in said plate place said hole made in the outer side in communication with each one of said holes made in the inner side, in such a way that said pressure relief valve is in communication with the inside of each one of said pipes,

and wherein inside each one of said pipes there is at least one float, which in turn comprises a body whose cross section has a shape that matches that of the cross section of the pipe, in such a way as to tightly divide the inside of the pipe into two compartments, an upper compartment, or gas side compartment, and a lower compartment, or water side compartment, and wherein the specific weight of said body is lower than that of the liquid circulating in the connected system and said body is movable between the two ends of the pipe owing to the effect produced by the thrusting action exerted by the liquid itself.

When the volume of the liquid present in the hydraulic system increases, the liquid flows into the expansion tank through said water side flange and, owing to the effect of the thrusting action exerted by the liquid, said floating body of each pipe moves upwards towards said gas side flange, thus reducing the volume of the gas compartment, inside which the pressure increases. The pressure increase is limited by means of said pressure relief valve, which is set according to the normal working pressure values of the system and opens in case of overpressure caused by malfunctions.

When the volume of the liquid present in the hydraulic system decreases, the liquid flows out of the expansion tank through said water side flange, in such a way that said floats of each one of said pipes move downwards towards said water side flange, thus reducing the pressure in said gas side compartments.

When the expansion tank empties completely, that is, when all the liquid flows out of each one of said pipes, said floats move downwards until reaching said water side flange. The underside of said floats is shaped in such a way as to tightly close the holes provided in suitable seats or projections, so that when the expansion tank empties completely no air can flow into the hydraulic system.

The number and arrangement of said pipes that make up said battery of the new expansion tank determine the shape and the overall dimensions of the tank itself. According to the type of boiler or hydraulic system, it is thus possible to design and assemble an expansion tank that can be integrated in the available space.

The characteristics of the new expansion tank will be highlighted in greater detail in the following description, with reference to the drawings which are attached hereto by way of non-limiting example.

Figure 1 shows a vertical sectional view of the new expansion tank (1).

Figure 2 shows a detailed sectional view of the water side flange (2).

Figure 3 shows a detailed sectional view of the gas side flange (3).

Figure 4 shows a sectional view of the centre part of the new expansion tank (1), where it is possible to see the floats (4) which are housed in each pipe (10) and tightly divide the inside of each one of said pipes (10) into two compartments (VI, V2).

Figure 5 shows a three-dimensional view of a possible embodiment of the new expansion tank (1).

The new expansion tank (1) comprises a battery (100) of pipes (10), consisting of two or more pipes (10) arranged side by side and parallel to one another.

Each one of said pipes (10) comprises a side wall (11), for example cylindrical or generically prismatic, with open lower end (12) and upper end (13).

Said battery (100), for example, can be constituted by one or more rows of aligned pipes (10), as shown in Figures 1 and 5, or by a plurality of pipes arranged in any way.

Said battery (100), therefore, is substantially in the shape of a parallelepiped or is made up of parts in the shape of parallelepipeds.

The expansion tank (1) comprises a lower flange, or water side flange (2), represented in detail in the sectional view shown in Figure 2.

Said water side flange (2) in turn comprises a substantially flat plate (21), wherein one side, or outer side (22), comprises at least one hole (23) for connection with the hydraulic system in which pressure and volume variations need to be compensated for.

Said connection hole (23), for example, is made in a cylindrical element (231) that projects from said outer side (22) and is preferably threaded on the outside (232) or in any case configured so that it is suitable for connection with a pipe of the connected hydraulic system.

The internal opposite side (24) of said plate (21), which faces towards said battery (100), comprises a plurality of seats or projections (241) suited to be tightly connected to said open lower ends (12) of each one of said pipes (10). Tightness is guaranteed, for example, by means of O rings (243) interposed between said projections (241) and the internal wall of said pipes (10).

Each one of said seats or projections (241) comprises at least one hole (242).

Furthermore, said plate (21) is provided with one or more channels (25) that place said connection hole (23) in communication with said holes (242) made in said projections (241).

In this way, the liquid can flow through said connection hole (23) towards the inside of all said pipes (10), through said channels (25) and said holes (242).

More specifically, according to the invention said connection hole (23) may communicate directly with the inside of one of said pipes (10), for example a centre pipe (10') of the battery (100) and also with said channels (25) through one or more holes (242') made in said projection (24 ) inserted in said centre pipe (10').

The new expansion tank (1) comprises also an upper flange, or gas side flange (3), shown in detail in the sectional view of Figure 3.

Said gas side flange (3) in turn comprises a substantially flat plate (31), wherein the outer side (32) comprises a hole (33) for the installation of a pressure relief valve (331), while the opposite internal side (34), which faces towards said battery (100), comprises a plurality of seats or projections (341) tightly connected to said upper open ends (13) of said pipes (10).

Tightness is guaranteed, for example, by means of O rings (343) interposed between said projections (341) and the inner wall of said pipes (10).

Said seats or projections (341) comprise one or more holes (342).

Said plate (31) of the gas side flange (3) is furthermore provided with one or more channels (35) that place said valve (331), which is installed in said hole (33) in the outer side (32), in communication with the inside of each one of said pipes (10).

Inside each one of said pipes (10) there is at least one float (4), in turn comprising a body whose cross section has a shape that matches that of the cross section of the pipe (10), in such a way as to tightly divide the inside of the pipe (10) into two compartments, an upper compartment, or gas side compartment (VI), and a lower compartment, or water side compartment (V2).

The specific weight of said float (4) is lower than that of the liquid circulating in the connected system and said float (4) is movable between the two ends (12, 13) of the pipe

(10), owing to the effect of the thrusting action exerted by the liquid.

The underside of said floats (4) is shaped in such a way as to tightly close said holes

(242) made in said seats or projections (241) of said water side flange (2).

For example, the lower surface (41) of each one of said floats (4) and/or the upper surface (244) of said projections (241) are equipped with sealing gaskets. According to the invention, in order to guarantee the correct assembly of the new expansion valve it is possible, but not necessary, to use tie rods (6) to be installed between said water side flange (2) and said gas side flange (3), as schematically represented in Figure 5.

Said tie rods (6), for example, are inserted and bolted in holes (61) correspondingly made in said flanges (2, 3).

According to the invention, for the installation of the new expansion tank it is possible to use brackets (5), constrained to said tank (1) in any way, for example to said water side flange (2), wherein each one of said brackets (5) comprises, for example, a first flat portion (51) facing said water side flange (2) and an angled portion (52) orthogonal to said first flat portion (51) and suited to be fixed, for example, to the wall or structure of the boiler.

The new expansion tank (1) can be completely made of plastic materials, which are especially suited to withstand operating pressures and any contact with corrosive substances.

These are the schematic outlines which are sufficient to the expert in the art to carry out the invention, consequently, on practical application variants can be developed which do not affect the substance of the innovative concept introduced herein.

Therefore, with reference to the description provided above and the drawings attached hereto, the following claims are expressed.