Automatic air vent

Claim 2

An automatic air vent for use in a liquid-filled system comprising a housing having a float chamber, and a float in said chamber under the control of the said liquid; and in which there is further provided an auxiliary chamber, an intermediate passage in sealed relation between said auxiliary chamber and said float chamber, valve means actuated by said float for closing-off said intermediate passage; a discharge orifice connected to the said auxiliary chamber; a piston in said auxiliary chamber, which said piston in a certain operative position thereof closes off said discharge orifice; and in which on the side of said piston remove from said intermediate passage said auxiliary chamber is in permanent communication with said float chamber.

Claim 3

An automatic air vent as claimed in claim 1, in which said piston is in the form of a differential piston, and in which said auxiliary chamber has a form adapted to that of said differential piston.

Claim 4

An automatic air vent as claimed in claim 1 in which said piston is loaded with spring pressure on the side thereof adjacent said intermediate passage.

Claim 5

An automatic air vent as claimed in claim 1 in which said float is provided with a guide pin on the end thereof adjacent said intermediate passage, which guide pin is aligned with said intermediate passage for projection therethrough into said auxiliary chamber for engagement by said piston, and said valve means includes an annular sealing ring around said guide pin.

Claim 6

An automatic air vent for use in a liquid filled system, said air vent comprising a housing defining a lower float chamber and an auxiliary chamber overlying said float chamber, an inlet passage in said housing opening into said float chamber, an intermediate passage between an upper part of said float chamber and said auxiliary chamber, a float in said float chamber, valve means at least in part positionable by said float for closing said intermediate passage, a piston movably mounted in said auxiliary chamber and sealingly dividing said auxiliary chamber into first and second end portions, said intermediate passage opening into said first end portion, a vent passage through said housing from said first end portion in a position to be closed off by said piston, and a further passage between the upper part of said float chamber and said second end portion for providing a pressure reaction on said piston when said valve means are closed to close-off said vent passage.

Claim 7

An automatic air vent for use in a liquid filled system, said air vent comprising a housing defining a lower float chamber and an auxiliary chamber overlying said float chamber, an inlet passage in said housing opening into said float chamber, an intermediate passage between an upper part of said float chamber and said auxiliary chamber, a float in said float chamber, valve means at least in part positionable by said float for closing said intermediate passage, a piston movably mounted in said auxiliary chamber and sealingly dividing said auxiliary chamber into first and second end portions, said intermediate passage opening into said first end portion, a vent passage through said housing from said first end portion in a position to be closed off by said piston, and a further passage between the upper part of said float chamber and said second end portion for providing a pressure reaction on said piston when said valve means are closed to close-off said vent passage.

Claim 8

An automatic air vent as claimed in claim 5 in which said inlet passage is an axial passage and directly underlies said float, and said float is provided with a guide pin on the end thereof remote from said intermediate passage, which guide pin is arranged to co-act with said inlet passage, and in which said guide pin is provided with abutment members arranged therearound to prevent said float from closing said inlet passage.

Claim 9

The air vent of claim 5 wherein said housing includes a first part defining said float chamber and a second part defining said auxiliary chamber, said first and second parts being in stacked relation, and means connecting together said first and second parts in sealed relation.

Claim 10

The air vent of claim 7 wherein a wall separates said float chamber and said auxiliary chamber, and said intermediate passage is through said wall.

Claim 11

The air vent of claim 5 wherein said intermediate passage is an axial passage and directly overlies said float.

Claim 12

The air vent of claim 5 wherein said inlEt passage and said intermediate passages are vertically aligned, and said float has projecting guide pins extending into said inlet passage and said intermediate passage.

Claim 13

The air vent of claim 1 wherein all communications of said auxiliary chamber with said float chamber are above said float.