Carburetor for gaseous fuels

A carburettor (100) for supplying gaseous fuels in internal combustion engines, comprising a main body (101) in which the following are defined:

• a. an intake section (102) for the fluid fuel at high pressure;
• b. a first pressure reduction section (1) comprising a first chamber (10) formed directly in the main body (101), a first deformable diaphragm (15) forming a sealing wall of the first chamber (10), a first shutter device (11) for selectively closing a first connecting conduit (110) between the supply section and the first chamber (10), the first shutter device (11) being connected for operation to the first deformable diaphragm (15) in such a way that the opening of the first shutter device (11) causes the first deformable diaphragm (15) to be deformed so as to reduce the volume formed by the first chamber (10), and suitable resilient means (16) for opposing the deformation of the first deformable diaphragm (15);
• c. a second pressure reduction section (2) connected to the first section (1) and comprising a second chamber (20) formed directly in the main body (101), a second deformable diaphragm (25) forming a sealing wall of the second chamber (20), a second shutter device (21) for selectively closing a second connecting conduit (120) between the first chamber (10) and the second chamber (20), the second shutter device (21) being connected for operation to the second deformable diaphragm (25) in such a way that the opening of the second shutter device (21) causes the second deformable diaphragm (25) to be deformed so as to reduce the volume formed by the second chamber (20), and suitable resilient means (26) for opposing the deformation of the second deformable diaphragm (25);
• d. a supply section (3) connected to the second pressure reduction section (2) and comprising a third chamber (30) formed directly in the main body (101), a third deformable diaphragm (35) forming a sealing wall of the third chamber (30), a third shutter device (31) for selectively closing a third connecting conduit (130) between the second chamber (20) and the third chamber (30), the third shutter device (31) being connected for operation to the third deformable diaphragm (35) in such a way that the opening of the third shutter device (31) causes the third deformable diaphragm (35) to be deformed so as to reduce the volume formed by the third chamber (30), and resilient means (36) for opposing the deformation of the third deformable diaphragm (35);
• e. a Venturi device (4) comprising a butterfly member (41) and connected to the supply section (3) so as to mix an air flow with gaseous fuel introduced through a supply conduit (150) connected to the third chamber (30), the resilient means (36) being made in such a way that the third shutter device (31) is normally in a closed position and is pushed into an open position as a result of the passage of the air flow through the Venturi device (4);
• wherein the Venturi device (4) forms a central portion of the carburettor (100), the first pressure reduction section (1) and the supply section (3) extending on opposite sides of a longitudinal axis of extension (x) of the Venturi device (4), the second supply section (2) being interposed between the first pressure reduction section (1) and the supply section (3);
• and wherein the supply section further comprises an actuating device (6) that can be actuated from the outside of the third chamber (3) and can push the third shutter device (31) into the open position, allowing gas to pass through the third connecting conduit (130) towards the third chamber (30).