An intake manifold includes a surge tank and left and right intake pipes containing one end sides each connected to the surge tank, and respectively extending to both side directions of the surge tank. A gas distribution passage portion to distribute exhaust gas to each of the left and right intake pipes is provided along a lower surface side of the surge tank and lower surface sides of the left and right intake pipes. An exhaust gas inlet and a gas distribution passage connected to the exhaust gas inlet are formed on the gas distribution passage portion. A communication hole to communicate an inside of each of the intake pipes and the gas distribution passage is formed on each of the left and right intake pipes.

An air intake port (10) for a lean-burn gasoline engine (110) comprises an air inlet (14), two air outlets (15a, 15b), and an air channel connecting the air inlet (14) to the two air outlets (15a, 15b) and comprising an upstream common duct (11) and two downstream port legs (12a, 12b), the two downstream port legs (12a, 12b) branching off from the common duct (11) at a bifurcation point (13). A total cross section of the air intake port (10) gradually decreases between the air inlet (14) and the two air outlets (15a, 15b). A gradient of decrease of the total cross section is locally reduced in a region adjacent the bifurcation point (13).

An air supply device for an internal combustion engine may include at least one air chamber and at least two intake pipes, which are connected to the at least one air chamber. The intake pipes may each be designed to supply air to respective cylinders of the internal combustion engine, and they each may have intake pipe end portion assigned to a corresponding inlet opening. Via the inlet openings, air can move from an air chamber interior of the at least one air chamber into respective intake pipe interiors of the at least two intake pipes and also via the intake pipe interiors to the cylinders. The intake pipe end portions may end in the air chamber interior and overlap in at least one direction, which is oriented perpendicularly to at least one center axis of at least one of the intake pipe end portions at a common overlapping region.

An intake port may include a short port and a long port. The short port may include a main extension portion extending from an intake air inlet; a main inclined portion inclined at a predetermined angle from the main extension portion toward a center of a cylinder; a main vertical portion which bends downward toward the cylinder from the main inclined portion; and a main intake air outlet formed at an end portion of the main vertical portion. The long port may include an auxiliary extension portion extending from the main extension portion; an auxiliary vertical portion bending downward toward the cylinder from the auxiliary extension portion; and a partition wall portion between the auxiliary extension portion and the auxiliary vertical portion, which allows the intake air to flow in a direction opposite to a direction in which the intake air introduced into the cylinder through the short port flows.

In an intake device for an internal combustion engine, a difference in the air-fuel ratio between the cylinders is reduced without increasing the lengths of the branch passages. An intake device (23) for an internal combustion engine (1) having at least three cylinders (3) includes: an intake chamber (30) configured to be connected with an air inlet (16); and multiple branch passages (31) connected at upstream ends (41) thereof to the intake chamber and connected at downstream ends thereof to intake ports (6) communicating with the cylinders, respectively, wherein the upstream ends of the branch passages are arranged in a direction of rotation about a predetermined center line X in a same order as an order of ignition of the cylinders.

A system for manufacturing a family of intake manifolds includes first and second intake molds. One of the first and second intake molds includes an outlet insert. A first intake manifold includes: a plenum chamber, a plenum chamber air inlet; a first number of intake runner passages; and the first number of outlets. Each of the outlets is fluidly connected to a corresponding one of the first number of intake runner passages. The second intake manifold includes: the plenum chamber; the plenum chamber air inlet; the first number of intake runner passages; and a second number of outlets. Each of the second number of outlets is fluidly connected to a corresponding one of the first number of intake runner passages. At least one of the first number of intake runner passages is not fluidly connected to any one of the second number of outlets of the second intake manifold.

An internal combustion engine includes a crankcase including a crankshaft and at least one cylinder coupled to the crankcase. The at least one cylinder has an intake port and defines an internal combustion chamber. The engine further includes a throttle body assembly with a throttle valve coupled to the intake port of the at least one cylinder and a throttle plate. Additionally, the engine includes a supplementary air inlet fluidly coupled to the intake port and spaced apart from the throttle valve. The supplementary air inlet is configured to receive a flow of air from a location downstream of the throttle plate when the throttle plate is in a fully closed position and the flow of air is directed into the combustion chamber through the intake port for combustion therein.

A first downstream part of an intake manifold has a first downstream passage configured to communicate with an intake port of a first cylinder head. A second downstream part of the intake manifold has a second downstream passage configured to communicate with an intake port of a second cylinder head. An upstream part is coupled to the first downstream part and the second downstream part. The upstream part is arranged upstream from the first and second downstream parts in the flow direction of intake air and has a first upstream passage and a second upstream passage. The material of the first downstream part and the material of the second downstream part both have higher rigidity than the material of the upstream part.

To provide an intake system of an internal combustion engine that can improve rigidity of a throttle body by strengthening a connection between plural components having an intake passage and further stabilize the opening degree of the throttle body. An intake system of an internal combustion engine includes: a plurality of throttle body members, each having at least one intake passage; and a plurality of structural connectors that are provided on respective throttle body members and connect adjacent the throttle body members with each other. The plurality of structural connectors includes a pair of structural connectors that are connected with each other in directions different from each other.

An air intake port (10) for a lean-burn gasoline engine (110) comprises an air inlet (14), two air outlets (15a, 15b), and an air channel connecting the air inlet (14) to the two air outlets (15a, 15b) and comprising an upstream common duct (11) and two downstream port legs (12a, 12b), the two downstream port legs (12a, 12b) branching off from the common duct (11) at a bifurcation point (13). A total cross section of the air intake port (10) gradually decreases between the air inlet (14) and the two air outlets (15a, 15b). A gradient of decrease of the total cross section is locally reduced in a region adjacent the bifurcation point (13).