The present invention relates to an automatic bleeding valve for hydraulic systems such as hot-water heating systems by thermosiphon circulation and the like, particularly for large airflow systems.

As it is known in hydraulic systems where a (usually hot) fluid circulates, for achieving an optimum operation of the system all traces of air are to be removed.

A convenient and known way to achieve the above result is to install a bleeding valve, either manually or automatically operated, at the highest point of the system.

The valves of this type comprise a floating member that rests into a seat and causes an automatic air discharge when the floating member is no longer in contact with the water.

However in systems with large flow rates and high pressures of the air to be ejected, the outcoming air jet directly strikes and lifts the float, thus closing the passage even when all the air has not been completely ejected and the float is in contact with water.

The invention aims to solve the above mentioned problem and to provide an automatic valve of the float type that achieves the following advantages over the presently used valves: a reduced size; a correct operation with large air flow rates;

a simple construction; a strongly limited cost; an improved reliability due to the absence of kinematic devices that might easily be blocked by the limestone present in hard waters at many locations.

The novel characteristics of the bleeding valve according to the invention will become evident from the characterizing portion of the claims.

The invention will now be disclosed with details with reference to the attached drawings, supplied only for exemplary and non limiting purposes, in which: Fig. 1 is a longitudinal cross sectional view of a device according to the invention in the automatic operation mode with the float in a lifted position (closed device); Fig. 2 is a longitudinal cross sectional view of a device according to the invention in the automatic operation mode with the float in a lowered position (open device); Fig. 3 is a longitudinal cross sectional view of a device according to the invention in the manual operating mode (closed device); Fig. 4 is a cross sectional view along line IV-IV of Fig. 3 illustrating the valve head and seat.

As shown in the Figures, a bleeding valve according to the invention substantially comprises: an outer cylindrically shaped body 1, having a threaded upper end 3

for securing a circular cover 5 which is equipped with a radial bleeding spout 35, and a threaded lower end 7 for securing the body 1 to the system, a sealing gasket 9 being interposed between the cover 5 and the outer body 1. A float 11 is movable inside the body 1 and has an inclined surface 13 for acting onto a stem 15 of a valve head member 17 for automatically opening and closing a bleeding orifice or opening 19 in the cover when the float 11 is lowered or lifted respectively, the stem 15 terminating with an enlarged portion 21 for sealingly abutting against a toric gasket or"0 ring"23. A return spring 25, usually a conical spring, urges the member 17 against said toric gasket 23. A plug 27 is housed in said cover 5 and allows for the automatic operation of the bleeding valve when the plug is unscrewed, or sets the bleeding valve to the manual operation mode when it is screwed and occludes the opening 19.

The sealing member or toric gasket 23 is common to both the automatic and the manual operating mode and such annular gasket is received in a groove 29 formed in the cover 5 and maintained therein without any dedicated fastening means. The end portion of the outlet opening is provided with an inwardly projecting caulked rim 33 to prevent the plug 27 from falling out of the cover after it has been loosened to enable the automatic operating mode.

The plug 27 is flush in a seat of the bleeding spout 35, so that no component protrudes from the cover 5 besides the spout 35. The automatic system for closing and opening the valve is housed in the bleeding spout 35, whereby the full volume of the body 1 is free for housing the movable float 11. A plurality of fins 37 is provided on the bottom surface of the float 11 for better conveying the air towards the exhaust or bleeding opening.

The lower end 7 of the body 1 is provided with a calibrated (gauged) hole 49 for air inlet and such hole opens into (communicates with) a first air expansion chamber 51.

Upstream of the opening 19, in the bleeding spout 35 a second expansion chamber 53 is formed, with two facing recesses 55 in correspondence of the enlarged portion 21, these recesses assisting the air outlet, and with two facing guides 56 shaped like circle arcs, and acting as guide members for the head 21 of the valve enlarged portion 21.

Moreover downstream of said toric gasket 23, towards the closing plug 27, a sealing annular gasket 41 is positioned, having a cross section shaped like a horizontal T, the stem 43 of which has a calibrated hole 45 for allowing the air passage. The plug 27, when screwed for the manual closure, abuts against the head 47 of the sealing gasket 41 downstream of the toric gasket (0 ring) 23.

Numeral reference 57 indicates two notches formed in the head of plug 27, through which the air escapes from the valve when the plug is open, both in the automatic and manual operating mode.