Cooking top with improved gas top burner

A gas burner for cooktops comprising:

• a lower body;
• a top cap, which closes said lower body on top;
• a first cylindrically-shaped hollow annular member adapted to be independently applied upon said lower body;
• a second substantially hollow annular member adapted to be independently applied upon said first annular member;
• an upper coaxial flame ring and a lower coaxial flame ring, the upper and lower flame rings having a same diameter but extending at two different heights, the flame rings having gas outlet ports arranged peripherally along the flame rings;
• a single gas injector;
• a single Venturi tube comprising a vertical convergent portion and a single expansion chamber for gas issuing from said single Venturi tube, said chamber being adapted to supply said upper and lower flame rings of the burner, wherein the lower flame ring is supplied with gas from the expansion chamber via a plurality of ducts which are arranged within an outer portion of said first annular member, and wherein an upper side of the gas outlet ports in the lower flame ring is delimited by said second annular member;
• and
• a plurality of pilot flames affecting said lower flame ring, these pilot flames being obtained by means of an upper contour of an outer rim of said first cylindrically-shaped, hollow annular member which remains separated, at some portions thereof that are spaced from each other, from an outer rim of the second annular member extending thereabove.