An air intake circuit for a heat engine is intended to be positioned between an air compression element and at least an upper portion of a hollow combustion chamber in a cylinder head of the engine. The air intake circuit includes the cylinder head, an air intake manifold, and at least one air intake duct. The circuit also includes at least one concave receptacle turned towards the outside of the engine, housed in a cavity of the cylinder head, and connected to a tubular element pushed into the at least one air intake duct.

The disclosure relates to an air inlet system for an internal combustion engine. The air inlet system has a cylinder head having an inlet channel for introducing inlet air into a combustion chamber of the internal combustion engine. The air inlet system has an air supply pipe piece, which is connected to the cylinder head and which at least partially forms an air supply channel, which opens in the inlet channel. The air inlet system additionally has thermal insulation, which is arranged in the air supply channel in order to reduce a heat transfer to the inlet air which flows in the air supply channel.

This air distributor (1) has an exterior casing defining an interior volume, an air inlet (4) opening into this interior volume, several air outlets (4) intended to convey air from the interior volume towards the cylinders of an engine, and a heat exchanger (8) arranged in the interior volume. The heat exchanger (8) comprises a stack of plates (10) of plastic material where adjacent plates (10) are arranged so as to define a set of intermediate spaces comprising closed intermediate spaces (12) in fluid communication to enable circulation of fluid through the stack of plates (10), and open intermediate spaces (14) configured to enable a passage of air through the stack of plates (10) from the air inlet (4) to the air outlets (6).

The intake manifold includes an intake air introduction port, a surge tank and a plurality of intake pipes. The intake air introduction port is connected to one end side of the surge tank in a direction in which the intake pipes are arranged. The surge tank is provided with a stepped portion over the direction in which the intake pipes are arranged. The stepped portion has an erected wall erected from a surface of the surge tank and connected to the plurality of intake pipes, and a curved wall connecting a tip side of the erected wall and the surface of the surge tank. Further, the surge tank is provided with a concave portion recessed toward the stepped portion at an intermediate portion in the direction in which the intake pipes are arranged.

An intake manifold including a surge tank having an inlet and a plurality of outlets extended along a first direction, and configured to form a space having a cross section larger than the inlet between the inlet and the plurality of outlets and a plurality of branch pipes. The space is formed by a bottom surface, an upper surface, a first surface extended from a first end of the bottom surface to a first end of the upper surface, and a second surface extended from a second end of the bottom surface to a second end of the upper surface. The inlet is provided at a substantially central portion in a first direction on the first surface, and the bottom surface includes a swelling portion swelled upwardly at a substantially central portion in the first direction.

An intake duct structure of a motorcycle includes front forks disposed on both of right and left sides of a head pipe of a body frame and a main frame extending obliquely backward and downward from the head pipe, wherein the intake duct structure extends from a front end of the motorcycle toward the head pipe and is formed in such a manner that an interfered area where a rotational orbit of the front forks at a time of steering overlaps the intake duct structure is elastically deformable.

An intake device for an internal combustion engine configures a flow passage for intake air that is drawn into combustion chambers. The intake device includes an intake manifold configuring multiple runners that respectively distribute intake air to multiple cylinders, a surge tank including a cavity that is connected to the runners and defines a convergence portion, a throttle body incorporating a throttle valve, and a connection pipe connecting the surge tank and the throttle body and configuring a curved flow passage extending between the throttle body and the surge tank. The connection pipe includes a partition plate that divides the curved flow passage into a circumferentially inner flow passage and a circumferentially outer flow passage.

A convergent nozzle is in a mixer housing and in a flow path from an air inlet of the mixer to an outlet of the mixer. A convergent-divergent nozzle is in the mixer housing and includes an air-exhaust gas inlet in fluid communication to receive fluid flow from the convergent nozzle and from the interior of the exhaust gas housing. A first nozzle module is configured to be received in the mixer housing and, when received in the mixer housing, define at least a portion of the convergent nozzle or the convergent-divergent nozzle. A second nozzle module is configured to be received in the mixer housing separate from the first nozzle module. The second nozzle module, when received in the mixer housing, is configured to define at least a portion of the convergent or the convergent-divergent nozzle. The second nozzle module has a different flow characteristic than the first nozzle module.

An off-road vehicle has: a frame including a rollover protection structure; two front wheels; two rear wheels; at least one seat; an internal combustion engine disposed rearward of the at least one seat, and being operatively connected at least one of: the two rear wheels, and the two front wheels; an engine air intake system fluidly connected to the engine for supplying air to the engine; a heat exchanger supported by the frame for cooling a vehicle fluid; a plenum defined at least in part by the heat exchanger, the plenum being disposed rearward of the at least one seat, an inlet of the engine air intake system being disposed in the plenum for supplying air from the plenum to the engine, and air from the plenum flowing over the heat exchanger for cooling the vehicle fluid; and a plenum air intake for supplying air to the plenum.

An air intake passage (30) has a third passage (37) that connects an intercooler (36) and a bottom portion of a surge tank (38) such that the intercooler (36) is positioned below the surge tank (38). A pair of wall portions (71, 72) configured to catch moisture is formed in a section from an upstream end portion of the third passage (37) to a connected portion between said third passage (37) and the surge tank (38).