Cooking hob gas burner

1. An improved gas burner, comprising:

an injector holder ( 2 ) configured to be fixed to a sheet metal ( 8 ) of a cooking hob, the injection holder being provided on its base with an injector ( 10 );

a burner body ( 14 ) resting on said injector holder ( 2 ), a circumferential passage being defined between said burner body and said injection holder for entry of primary air intended to form a combustion mixture with gas leaving said injector ( 10 ); and

a cover ( 28 ), formed from a single piece of drawn sheet metal, positioned on said burner body ( 14 ),

wherein said cover comprises a first circumferential flange ( 30 ) provided with a plurality of elongated apertures ( 32 , 40 ) of essentially vertical extension, for passage of the combustion mixture which generates a ring of main flames ( 34 ),

wherein a radial venturi effect chamber ( 36 ) is defined in an interspace between said cover and an upper surface of said burner body, said radial venturi effect chamber having a wider end facing said elongated apertures,

wherein said burner body further comprises an annular band ( 22 ) extending upwardly from an outer circumferential edge of said burner body,

wherein a second circumferential flange extends downward from said first circumferential flange toward said burner body, said first circumferential flange extending radially more than said second circumferential flange so that the second circumferential flange is concentric to, and radially interior to, the annular band, and

wherein a plurality of first small apertures ( 24 ) are defined in said second circumferential flange for the passage of the combustion mixture to feed an annular stabilization flame ( 26 ) for the ring of main flames, said first small apertures being positioned axially below a lower surface of said first circumferential flange,

whereby said annular stabilization flame is formed in an annular space defined by said lower surface of said first circumferential flange, said second circumferential flange, and said annular band, and

whereby said plurality of first small apertures is hidden from view by said annular band.

2. The gas burner as claimed in claim 1 , wherein the sheet metal which forms the cover has a thickness between 1.0 and 1.7 mm.

3. The gas burner as claimed in claim 1 , wherein said elongated apertures ( 32 , 40 ) have a height between 3.0 and 7.0 mm and a width between 1.0 and 1.7 mm.

4. The gas burner as claimed in claim 1 , wherein a surface of said circumferential flange ( 30 ) is inclined in relation to a vertical axis.

5. The gas burner as claimed in claim 1 , wherein said annular band ( 22 ) of the burner body ( 14 ) is exposed and is inclined by an angle corresponding to an inclination of the circumferential flange ( 30 ) of said cover ( 28 ), such as to define line continuity between said cover ( 28 ) and an exposed portion of said body ( 14 ).

6. The gas burner as claimed in claim 1 , wherein said cover ( 28 ) has a radial length less than a radial length of the annular band ( 22 ) of the burner body ( 14 ).

7. The gas burner as claimed in claim 1 , wherein said elongated apertures ( 32 ) have axes lying in radial vertical planes of the gas burner.

8. The gas burner as claim 1 , wherein said elongated apertures ( 40 ) have axes inclined to radial vertical planes of the gas burner.

9. The gas burner as claimed in claim 1 , wherein said cover ( 28 ) comprises an essentially flat upper surface ( 29 ) with an edge bent downwards to form said circumferential flange ( 30 ).

10. The gas burner as claimed in claim 1 , wherein:

said burner body ( 14 ) comprises a central portion and an annular portion which is concentric to the central portion and is separated therefrom by an annular cavity,

wherein said cover comprises a first cover and a second cover, and said ring of main flames comprises a first ring of main flames and a second ring of main flames,

wherein said first cover defines, with said central portion of the burner body ( 14 ), a central chamber from which the first ring of main flames emerges through said elongated apertures ( 32 ) of essentially vertical extension of said cover ( 28 ), and

wherein said second cover defines, with said annular portion of said body ( 14 ), an annular chamber from which the second ring of main flames emerges through said elongated apertures ( 32 ) of essentially vertical extension of said at least one cover ( 28 ).

11. The gas burner as claimed in claim 10 , wherein said cover ( 28 ) comprises:

said first cover is of circular shape and, with said central portion of said body ( 14 ), defines said central chamber, and

said second cover is of annular shape and, with said annular portion of said body ( 14 ), defines said annular chamber.