Device for forming and metering an air and fuel mixture for an internal combustion engine

A device for forming and metering an air and fuel mixture for an internal combustion engine, said device comprising:

• a body (1) in which is formed a chamber (2) in which fuel is mixed with air;
• a cylindrical mixture delivery duct (6) having an opening controlled by a circular contour throttle valve (7) having a throttle axis;
• a cover (4) fitted on the said body and in which are formed a duct (3) for supplying air inside the said mixing chamber, and a seat (13) for a fuel injector (12) for supplying atomized fuel into the said mixing chamber, said cover also being provided with a pressure regulator (17) for maintaining constant pressure of the fuel supplied by the said injector;
• the said cover being provided with a tubular supporting element (14) for the said injector and located inside the said air supply duct (3);
• the said tubular supporting element having an axis, an inner surface, and being connected to the said cover by a pair of connecting bridges (15, 16), and being formed inside with the said seat (13) for the said injector and an annular chamber (27) for fuel supplied to the said injector;
• and further including:
• at least a first straight fuel duct portion (28) connecting the said annular chamber (27) to a first fuel intake fitting (28a) and forming a first acute angle with the axis of the said tubular supporting element (14) and running through one of the said connecting bridges (16);
• a second straight fuel duct portion (29) connecting the said annular chamber (27) to the said pressure regulator (17) and forming a second acute angle with the axis of the said tubular supporting element and running through the other (15) of the said connecting bridges;
• the said second angle being sufficiently small for ensuring that the generating lines (30) of the surface of the said second straight duct portion intersect the inner surface of the said tubular supporting element (14) only once, thus enabling the said duct to be drilled by means of a tool inserted inside the said tubular supporting element;
• the said mixing chamber (2) comprising at least a first (18) and second (19) portion defined by differently tapered surfaces, and a third portion (20) defined by a cylindrical surface equal in diameter to the said cylindrical mixture delivery duct (6) and having a top edge;
• and
• the axial length of the said cylindrical surface of the said third portion of the said mixing chamber, measured between the throttle axis of the said throttle valve and the top edge of the said third portion, being at least equal to the radius of the said circular contour of the said throttle valve.

A device for forming and metering an air and fuel mixture for an internal combustion engine, said device comprising:

• a body (1) in which is formed a chamber (2) in which fuel is mixed with air;
• a cylindrical mixture delivery duct (6) having an opening controlled by a circular contour throttle valve (7) having a throttle axis;
• a cover (4) fitted on the said body and in which are formed a duct (3) for supplying air inside the said mixing chamber, and a seat (13) for a fuel injector (12) for supplying atomized fuel into the said mixing chamber, said cover also being provided with a pressure regulator (17) for maintaining constant pressure of the fuel supplied by the said injector;
• an air bypass (41) connecting an air intake hole formed in the said cover (4) with a portion (42) of the said mixture delivery duct downstream from the said throttle valve;
• the said bypass being provided with a plugging member (46) controlled by an actuator (47);
• the said bypass coming out inside a distribution chamber (49) formed in the said body and communicating with the said portion (42) of the said mixture delivery duct via a pair of slots (53) arranged symmetrically in relation to a plane through the axis of the said delivery duct and perpendicular to the axis of the said throttle valve;
• the said body including a circuit for heating the said distribution chamber (49) and parts of the said body adjacent to the same, and the said circuit comprising at least three straight duct portions (55, 56, 57) located in a plane perpendicular to the axis of the said mixture delivery duct and over the said distribution chamber (49);
• the said mixture chamber (2) comprising at least a first (18) and second (19) portion defined by differently tapered surfaces, and a third portion (20) defined by a cylindrical surface equal in diameter to the said cylindrical mixture delivery duct (6) and having a top edge;
• and
• the axial length of the said cylindrical surface of the said third portion of the said mixing chamber, measured between the throttle axis of the said throttle valve and the top edge of the said third portion, being at least equal to the radius of the said circular contour of the said throttle valve.

A device for forming and metering an air and fuel mixture for an internal combustion engine, said device comprising:

• a body (1) in which is formed a chamber (2) in which fuel is mixed with air;
• a cylindrical mixture delivery duct (6) having an opening controlled by a circular contour throttle valve (7) having a throttle axis;
• a cover (4) fitted on the said body and in which are formed a duct (3) for supplying air inside the said mixing chamber, and a seat (13) for a fuel injector (12) for supplying atomized fuel into the said mixing chamber, said cover also being provided with a pressure regulator (17) for maintaining constant pressure of the fuel supplied by the said injector;
• the said mixing chamber (2) comprising at least a first (18) and second (19) portion defined by differently tapered surfaces, and a third portion (20) defined by a cylindrical surface equal in diameter to the said cylindrical mixture delivery duct (6) and having a top edge;
• the axial length of the said cylindrical surface of the said third portion of the said mixing chamber, measured between the throttle axis of the said throttle valve and the top edge of the said third portion, being at least equal to the radius of the said circular contour of the said throttle valve;
• a cavity (58) in said body (1) communicating with a portion (42) of the said mixture delivery duct (6) downstream from the said throttle valve via a slot (59);
• the said cavity communicating with at least a duct for transmitting a pressure signal from the said portion to a pressure indicating device;
• the said cavity being located, in relation to the axis of the said mixture delivery duct (6), diametrically opposite a distribution chamber (49) and being separated from the said duct by a substantially cylindrical wall (61).