Gas cock for gas burner

1. A gas cock for a gas burner provided with a pilot flame, comprising:

a cock body, wherein a plug receiving seat and a gas passage opening for passage of gas from or to the plug receiving seat are formed; and

a conical plug, comprising a side wall which extends around a central conical plug axis and which is housed gas-tight in the plug receiving seat, said side wall comprising an inner wall surface which defines an inner cavity of the conical plug and an outer wall surface opposite to the inner wall surface, said conical plug comprising a plug opening for the passage of gas from or to the plug receiving seat through the inner cavity of the conical plug according to an adjustable angle of rotation between the cock body and the conical plug,

wherein in the side wall of the conical plug, a groove is formed on a side of the outer wall surface, said groove being connected to the plug opening,

wherein said groove is adapted to be positioned at least partially at the gas passage opening of the cock body as a function of the adjustable angle of rotation,

wherein said groove comprises at least one modulating portion which extends predominantly between a first angular position and a second angular position along a circumferential direction of rotation of the conical plug,

wherein said groove, between the first angular position and the second angular position has an increasing or decreasing depth, said depth being measured in a radial direction perpendicular to the side wall, and

wherein downstream of the second angular position, in a direction proceeding from greater depth to smaller depth of the groove, a blind pocket is obtained, having a pocket depth greater than the depth of the groove measured at the second angular position.

2. The gas cock for a gas burner according to claim 1 , wherein the groove, between the first angular position and the second angular position has a constantly increasing depth or a constantly decreasing depth.

3. The gas cock for a gas burner according to claim 1 , wherein the groove is a blind groove at least in a section between the first angular position and the second angular position.

4. The gas cock for a gas burner according to claim 1 , wherein the groove has a cross section lying on a plane perpendicular to the central conical plug axis, substantially in a “C” or “U” shape, with an open region facing the outer wall surface.

5. The gas cock for a gas burner according to claim 1 , wherein the at least one modulating portion extends along the circumferential direction by a portion angle greater than 90°.

6. The gas cock for a gas burner according to claim 1 , wherein the at least one modulating portion extends along the circumferential direction by a portion angle greater than 150°.

7. The gas cock for a gas burner according to claim 1 , wherein the groove has a transverse dimension, parallel to the central conical plug axis, smaller than or equal to a transverse dimension of the plug opening.

8. The gas cock for a gas burner according to claim 1 , wherein the conical plug comprises an auxiliary groove, spaced with respect to the groove in an axial direction of the central conical plug axis, said auxiliary groove extending substantially in the circumferential direction and being configured for the passage of gas towards an auxiliary opening formed in the cock body different from the gas passage opening to deliver a gas flow rate lower than a gas flow rate of the gas passage opening.