CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application claims priority from Italian utility model application no. 202019000003512 filed on 07/10/2019, the entire disclosure of which is incorporated herein by reference.

TECHNICAL FIELD

The invention relates to an air vent valve with float. The invention finds preferred, though non-exclusive application in closed-circuit heating systems, to which reference will be made in the description below without thereby losing in generality.

Closed-circuit heating systems require the use of air vent valves in order to vent air from points where it builds up, such as risers, pump bodies and other devices.

BACKGROUND ART

According to a first known type, an air vent valve with float comprises a cup-shaped body to contain the float and a lid screwed onto the cup-shaped body, which houses a valve body defining a vent duct. A shutter, which is housed in the lid, but is kinematically coupled to the float, is kept in a closed position against a mouth of the vent duct by a spring. The build-up of air in the valve produces a progressive lowering of the float and the consequent movement of the shutter towards an opening position, which allows air to be vented.

In those cases in which the valve is applied to a device having an outer casing of its own, the cup-shaped body is not needed and the lid can directly be applied to the casing of the device.

However, this means that the float is exposed and must be protected during storing, transportation and assembly.

Italian utility model no. 00237091 discloses, to this aim, the use of a drum consisting of a ring, which is mounted in the lid through interference, and of a gantry element projecting from the ring in an integral manner and formed by two lateral uprights, which are parallel to one another and to the direction of movement of the float, and a cross member, which joins the ends of the uprights. A problem arising from this solution is the interference fit of the drum ring inside the relevant seat of the valve body, which can cause connection reliability problems.

In order to eliminate the drum and the relative assembly problems, EP 1 927 802 discloses a solution in which the shutter is stopped, in its downward movement, by an inner striker of the pump body.

This solution is not free from drawbacks either, since the use of a striker integral to the valve body makes the automatic assembly of the valve difficult. DISCLOSURE OF INVENTION

The object of the invention is to provide an air vent valve which is free from the drawbacks affecting know valves and described above. The aforesaid object is reached by an air vent valve comprising: a cup-shaped casing provided with a lateral wall; a valve body, which is housed in a radial seat of the casing and defines a vent duct ending in an axial end of the valve body; a vertically movable float; and a shutter, which is kinematically coupled to the float and is movable between a lifted closing position, in which it closes the valve and cooperates with the axial end of the valve body in a sealing manner, and a lowered position, in which it allows air to be vented through the vent duct of the valve body; and a stop element for the float, which is designed to limit the downward stroke thereof relative to the casing, wherein the stop element comprises a cross member, which is arranged crosswise under the float and is constrained to the casing in a snapping manner at its ends.

Thanks to the use of a stop element that is fitted in a snapping manner to the casing of the valve at its ends, the drawbacks of known solutions are eliminated. In particular, problems deriving from the interference fit of an annular drum and mounting problems in connection with the use of a stop element that is fixed inside the casing are eliminated. According to a first embodiment, the stop element consists of the cross member and is snap-fitted, at its ends, to respective uprights integrally projecting from the lateral wall of the casing.

This solution improves guidance of the float during assembly by means of the fixed uprights.

According to another embodiment, the stop element is gantry shaped and integrally comprises two uprights, which are designed to be snap coupled to respective diametrically opposite seats of the lateral wall, and a cross member. BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be best understood upon perusal of the following description of two preferred embodiments, which is provided by mere non-limiting example and with reference to the accompanying drawings, wherein: figure 1 is a perspective view of an air vent valve according to a first embodiment of the invention; figure 2 is an exploded, perspective view of the valve of figure 1; figure 3 is a cross section of the valve of figure 1 according to a first axial plane; figure 4 is a cross section of the valve of figure 1 according to a second axial plane, which is perpendicular to the first axial plane; figure 5 is a cross section of a second embodiment of the valve according to an axial plane corresponding to the one of figure 4; and figure 6 is a partially exploded, perspective view of the valve of figure 5.

BEST MODE FOR CARRYING OUT THE INVENTION With reference to figures 1 to 4, numeral 1 indicates, as a whole, an air vent valve according to the invention.

The valve 1 comprises a cup-shaped casing 2 with a vertical axis A, which has a substantially cylindrical lateral wall 3 and a substantially flat upper wall 4. The casing 2 is configured to be coupled to a fitting of a pump body or of another device that is part of the system.

The lateral wall 3 has an intermediate outer circular rib 5 acting as an abutment for a sealing gasket 6 of the 0- ring type, which is designed to seal, in use, the housing seat of the valve 1. The lateral wall 3 has two diametrically opposite flat portions 7, which are arranged between the rib 5 and the upper wall 4 and are designed to allow the lateral wall 3 to be easily grabbed in order to manually or automatically move the casing 2.

The lateral wall 3 further forms an inner projection 8 provided with a radial through seat 9, with a horizontal axis B, which houses in a sealing manner, and preferably screwed therein, a known valve body 10, which is not part of the invention and, therefore, is described very briefly. The valve body 10 (figure 3) defines a horizontal axial duct 14, which leads to an inner axial end 15 of the valve body 10 and communicates with a vent duct 16 obtained in a tubular appendage 17 of the upper wall 4. A cap 18, which is screwed onto an end of the appendage 17, protects the vent duct 16 from dirt and foreign bodies, but it is provided with vent openings 19 in order to allow air to flow out when, once the valve 1 is installed, it is partially unscrewed.

On the valve body 10 there is mounted, by means of a helical spring 23, a shutter 24, which is designed to seal, in the absence of external forces, the axial end 15 of the valve body, thanks to the returning force exerted by the spring.

More in particular, the spring 23 is screwed on respective threads of the valve body 10 and of the shutter 24 and is axially pre-loaded so as to "pull" the shutter 24 against the end 15 of the valve body 10. In order to facilitate the seal, the shutter 24 is provided with a front sealing element 25 made of an elastomer material, which is inserted in a seat 26 of the shutter 24 (figure 3).

The shutter 24 is provided, at an axial end thereof opposite the front sealing element 25, with an oblong axial shank 27, whose purpose will be better described below.

The valve 1 further comprises a float 28, which is partially housed inside the casing 2 and is free to axially (vertically) move inside the latter. More in particular, the float comprises a substantially cylindrical main portion 30, from which two parallel walls 31, which are symmetric relative to the axis A, project upwards. The walls 31 are designed to be placed within the flat portions 6 of the casing 2 (figure 4) so as to guide, in a prismatic manner and with a given clearance, the vertical movement of the float 28 relative to the casing 2.

The two walls 31 are connected to one another in an integral manner, in the area of the upper vertexes thereof opposite the valve body 10, by an arc-shaped cross member 32, which rests, in use, on the shank 27 of the shutter 24, so as to kinematically couple the latter to the float 28.

The downward movement of the float 28 is limited by a stop element 33, which is constrained to the casing 2 and extends crosswise relative to the float.

According to the first embodiment shown in figures 1- 4, the stop element 33 consists of a cross member, which is snap fitted, at its ends, to respective uprights 34, which integrally and axially project from the lateral wall 3 of the casing 2, in diametrically opposite positions. In particular, the uprights are provided with C-shaped end seats 35, where respective reduced-diameter end portions 37 of the stop element 33 are snap fitted.

The main portion 30 of the float 28 has a pair of lateral axial grooves 35, which are engaged with clearance by the uprights 34, and a lower diametral groove 38, which is designed to receive the stop element 33 when the float 28 is in the lowered position. This happens, for example, during transportation and storage of the valve 1. The operation of the valve 1 is the following.

In the absence of air in the system, the float 28 is in a lifted position due to the hydrostatic thrust of the water in the system, as shown in figure 3. Therefore, the spring 23 keeps the shutter 24 in contact with the valve body 10, thus creating a seal that prevents water from flowing out.

In case air builds up inside the casing 2, the float 28 moves downwards due to the thrust of the pressure of the air and acts, with the cross member 32, upon the shank 26 of the shutter 24, which inclines downwards. The misalignment of the shutter 24 relative to the valve body 10 determines a loss of seal between them, with a consequent release of air towards the outside through the ducts 14 and 16.

As soon as the air has been vented, the float 28 can go back to the position of figure 3, thus closing the valve 1 again.

The valve of figures 5 and 6, which is indicated as a whole with numeral 40, differs from the valve 1 in that, in this case, the stop element 41 is gantry-shaped and integrally comprises two uprights 42 and a cross member 43. The uprights 42 are snap fitted at their ends in respective seats 44 provided in the lateral wall 3 of the casing 2.

The operation of the valve 40 is identical to the one of the valve 1 described above.