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.

An EGR gas distributor includes an inflow portion into which EGR gas that has passed through an EGR valve flows, a first EGR port connected to a section of the intake manifold in which intake air introduced into the first cylinder flows, a second EGR port connected to a section of the intake manifold in which intake air introduced into the second cylinder flows, a first gas passage that connects the inflow portion and the first EGR port to each other, and a second gas passage that connects the first gas passage and the second EGR port to each other. A shortest path between the first EGR port and the second EGR port is longer than both of a shortest path between the inflow portion and the first EGR port and a shortest path between the inflow portion and the second EGR port.

An EGR gas distributor includes an inflow portion into which EGR gas that has passed through an EGR valve flows, a first EGR port connected to a section of the intake manifold in which intake air introduced into the first cylinder flows, a second EGR port connected to a section of the intake manifold in which intake air introduced into the second cylinder flows, a first gas passage that connects the inflow portion and the first EGR port to each other, and a second gas passage that connects the first gas passage and the second EGR port to each other. A shortest path between the first EGR port and the second EGR port is longer than both of a shortest path between the inflow portion and the first EGR port and a shortest path between the inflow portion and the second EGR port.

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.

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 engine device including: an EGR device configured to circulate, as EGR gas, a portion of exhaust gas exhausted from an exhaust manifold manifold to an intake manifold; and an EGR cooler configured to cool EGR gas and supply the EGR gas to the EGR device. The EGR cooler includes a heat exchanger and a pair of flange portions. The heat exchanger has a coolant passage and an EGR gas fluid passage alternately stacked. The flange portions are disposed on the heat exchanger. An outlet of the coolant is disposed in one of the flange portions, while an inlet of the coolant is disposed in the other flange portion. An inlet of the EGR gas is disposed in one of the flange portions, while an outlet of the EGR gas is disposed in the other flange portion.

A bottom surface of a surge tank has such a shape that, in a vehicle-mounted state, the bottom surface is positioned below a lower surface at an upstream end of each of a plurality of independent passages and comes closer to the lower surface at the upstream end of each of the plurality of independent passages in a vertical direction farther away from a connected portion between the surge tank and a third passage in a cylinder array direction.

Provided is an intake manifold structure for an internal combustion engine including an intake manifold defining a plurality of branch passages (13) communicating with corresponding intake ports (6) of the internal combustion engine (1) arranged in a cylinder row direction thereof, and provided with additional gas introduction ports (29) communicating with the respective branch passages, and an additional gas introduction passage forming member (16) attached to the intake manifold, and defining an additional gas inlet (35) and additional gas introduction passages (14) communicating the additional gas inlet with the corresponding additional gas introduction ports, wherein the additional gas introduction passage forming member extends across the branch passages, and is provided with a guide wall (33) for defining the additional gas introduction passages in cooperation with an outer surface of the intake manifold and an inner surface of the additional gas introduction passage forming member.

Provided is an intake manifold structure for an internal combustion engine including an intake manifold defining a plurality of branch passages (13) communicating with corresponding intake ports (6) of the internal combustion engine (1) arranged in a cylinder row direction thereof, and provided with additional gas introduction ports (29) communicating with the respective branch passages, and an additional gas introduction passage forming member (16) attached to the intake manifold, and defining an additional gas inlet (35) and additional gas introduction passages (14) communicating the additional gas inlet with the corresponding additional gas introduction ports, wherein the additional gas introduction passage forming member extends across the branch passages, and is provided with a guide wall (33) for defining the additional gas introduction passages in cooperation with an outer surface of the intake manifold and an inner surface of the additional gas introduction passage forming member.