DESCRIPTION

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Field of application of the invention

The present invention relates to the field of seamless pipe connections for applications in commercial, domestic and industrial heat exchange fluidic systems and air conditioning. More specifically, the present invention relates to a method and a directly obtained product for the production of tanks and filter elements.

State of the art

In the state of the art, it is known that said tanks are made of a single body generally of metal (e.g., copper, iron, aluminum, steel) and have two shaped ends to allow connection by pipes to the system of which they will be a part .

The connection of this component in object to the rest of the circuit to which it is mounted is made by welding tubes (one inlet and one outlet) at both ends to allow the passage of a heat transfer fluid. The tank is connected to these tubes either by welding or by rings or plastic deformation joints. In the latter case, the connecting tubes are socked over or into the tank connections and the ring, which, during application e.g., with a dedicated tool, radially compresses the pipe sections and ducts so as to make a non-releasable, fluid-tight mechanical connection.

Shaping of tank connections can currently be done by hammering, convexing or tapering.

Welds applied to the tank can be flame or induction welded and lead to a number of drawbacks, including:

- sealing problems and leakage of the same;

- difficulty in verifying them prior to pressure testing of the entire system;

- possible deterioration of them due to vibration and temperature excursions;

- dangerousness in the use of open flames in uncontrolled environments (e.g., installations and maintenance carried out at third parties);

- problems of coupling between different materials (especially copper, aluminum, steel, brass);

- need for specific training and skills of operators involved in the welding process;

- high costs of equipment to carry out welding operations.

Summary of the invention

The basic idea of the present technical solution is to devise an casing for the eventual housing of one or more filter elements that has no welds connecting it to the heat exchange fluidic system of which it will be a part. More specifically, said casing will connect to a mechanical joint by radial deformation, e.g., of the type a lokring joint, directly to the pipes part of the system, and therefore said casing will be conformed in such a way that both ends are such that they meet technical requirements that allow them to be attached directly to the system with the help of the mechanical joint. The shape of the tank is entirely obtained by plastic deformation preferably by hot forming of the intended metal, e.g., copper, aluminum, steel and brass.

The technical requirements of the component connections in order to properly apply radial deformation joints are:

- smooth or polished outer surfaces;

- ends with a cylindrical surface of length > 12 mm to be able to apply clamp or jaw pressure over the entire length of the joint;

- calibration of the outer diameter of the ends in order to properly fit the joint;

- calibration the inner diameter of the ends to be able to properly fit the pipe connection to the system.

The present casing is obtained by deformation inside a metal cylinder, also referred to as a mold, of a piece of metal pipe. The method for obtaining it can therefore be considered a variant of the known tapering process.

Brief description of the figures

Further purposes and advantages of the present invention will be clear from the following detailed description of an example embodiment of the invention (and variants thereof) and the accompanying drawings given for explanatory and non-limiting purposes only, in which:

- Figure 1 shows a radial compression gripper tool required to couple a mechanical joint applied in the invention;

- Figure 2 shows an example of a radial interference joint according to the present invention;

- Figure 3 shows in front view, according to a form of realization, a filter drier body A where B indicates a support, C a filter net, D a molecular sieve, E connections of filter drier body A;

- Figure 4 schematically shows a heat transfer fluidic system comprising: a duct 1 for a heat transfer fluid having second maximum external transverse dimension D2, a casing 2 having a first maximum internal transverse dimension DI and including a central cylindrical body 4 and at least one end collar 5 having a third maximum internal transverse dimension D3, a radially deforming mechanical joint 3;

- Figure 5 shows in axonometric, frontal, and sectional views, respectively, an example of filter net C;

- Figure 6 shows in side and sectional views, respectively, a metal cylinder suitable for conforming tank A.

The same numbers and reference letters in the figures identify the same elements or components.

The elements and features illustrated in the various preferred forms of realization, including drawings, may be combined with each other without, however, falling outside the scope of protection of this application as described below .

Detailed description of examples of realization

The filter elements or liquid storage tanks, more generically referred to as casings 2, which are the subject of this patent application, comprise a central cylindrical body 4 and at least one first connection end to a heat transfer fluid circuit. In alternative forms of embodiment, the element/tank may comprise a central cylindrical body 4 and a first and second connecting ends to define a fluidic element traversed by the heat transfer fluid of the circuit, particularly refrigerant.

Said ends have a variation in diameter between that of the central body 4 and that of the circuit pipe(s) to which the filter element or tank 2 is fluidically connected. Specifically, they define the interface on which to attach the joint 3 for mechanical coupling to the rest of the heat exchange circuit of which they will be a part. Each end comprises a collar 5, i.e., a hollow cylindrical body suitable for connecting to a conduit 1 of the circuit via a mechanical joint e.g., a mechanical radial deformation joint 3 such as a lokring. Said conduit 1 has second maximum outer transverse dimension D2 smaller than the first maximum inner transverse dimension D1 of the casing 2.

The inner diameter D3 of collar 5 is smaller than the inner diameter D1 of central body 4. The inner diameter D3 of collar 5 is generally in the range of 1.9 to 12.2 mm depending on the required specifications.

Advantageously, the new element/tank 2 has the characteristic of being made entirely by plastic deformation. The major difference, compared with the known art, lies in the fact that element/tank 2 does not require any welded components for connection to the circuit via the mechanical radial deformation joint 3. As shown in Figure 2, as a result of the compression applied by the gripper in Figure 1, collar 5 and duct 1 have corresponding annular depressions A1, A2 that are sealed for heat transfer fluid, even in an aeriform state.

The new element/tank 2 is obtained by deformation of a metal tube whose length is such that it includes both that of the central cylindrical body 4 and that of the collar 5.

For example, the equipments used are:

1- Cut-off machine to bring the tubes to size

2- Dosing machine to insert internal mechanical filter components and desiccant material

3- Machine to deform the ends and calibrate the collars

4- Machine to cap the ends to ensure cleanliness and avoid exposure to atmospheric moisture during transportation and storage

5- Machine to mark the component with the necessary identification codes.

Said element or tank 2 to be connected directly to the circuit by means of the mechanical radial deformation joint 3, following the method for obtaining it described below, shall possess the dimensions provided for the use of the joint and, according to a non-limiting example, the following technical characteristics: collar diameter: 1.40 mm - 22.2 mm inside length of the collar: minimum 12 mm roughness (Ra) of the collar < 3.20 μ collar hardness > 2.75 and collar thickness > 0.20 mm thermal conductivity greater than 200 W/(m-K);

The length of the collar 5 must be such that it has the appropriate surface area to be able to fit the joint 3 and properly position the tool to apply the force required for the coupling.

The surface of collar 5 must be free of external scoring in order to uniformly apply an anaerobic, one-component mastic- based sealing fluid required to anchor a component of joint 3 over the length of collar 5.

The diameter range of collars 5 from 1.40 mm to 22.2 mm inside is due to the need to adapt the invention to the measurements of standard piping used in refrigeration systems.

Tubes with diameters ranging from 1.40 mm to 3.70 mm are called capillary tubes and are intended to carry the refrigerant from condensing pressure to evaporating pressure.

Tubes from diameter 3.70 mm to 22.2 mm are required to flow the fluid inside the refrigeration circuit.

The procedure for obtaining said element/tank includes the following steps:

- cutting a piece of metal pipe of such length that the piece includes the central cylindrical body 4 and at least one collar 5;

- insert the internal components, if required for the finished product; insertion of the internal components may be done at a later or alternative stage than shaping the ends;

- clamp the piece of metal pipe in a vise, pliers or jaw;

- adequately lubricate the ends to be shaped;

- insert the metal tube into a metal cylinder, called the first mold, which possesses within it a cylindrical shape shaping that corresponds to the length of the collar 5;

- if necessary from the thickness of the metal material, operate a system of resistors designed to deform by its own heat the metal tube which will undergo a shrinkage in section to conform the collar 5 within the groove; - execution by the mold of a controlled pressure of between 2,000 N and 175,000 N on one end of the metal tube;

- application, at a later station, by a second die, mirroring the first die, of pressure on the other end of the metal tube to form the second collar opposite the first;

- the piece of metal tube to be deformed is fixed in order to withstand the force required to deform the ends.

It should be noted that the length of collar 5 varies depending on the geometry, e.g. length, of the radial deformation joint used. Generally, collar 5 must be at least 12 mm long. The greater length of collar 5 than that of joint 3 is necessary for the housing of the tool, e.g., collet, for clamping the joint.

The element/tank 2 described above is part of a heat exchange fluidic system by which is meant a refrigeration plant, a freezing plant, a freezing plant, an air conditioning plant, or even a heat pump system. The fluid flowing within these systems is understood to be a heat transfer fluid e.g., a refrigerant.

Variations in realization to the non-limiting example described are possible, without, however, going beyond the scope of protection of the present invention, encompassing all realizations equivalent to the content of the claims for a technician of the field.

From the above description, the field technician is able to realize the object of the invention without introducing further construction details.