A partition plate is configured to separate an intake passage formed by an intake pipe to be coupled to a combustion chamber into a first intake passage and a second intake passage. The first intake passage is openable and closable by a valve. A shape of a first cross section orthogonal to an extending direction of the intake pipe is set on the basis of a shape of a surface of the intake pipe that faces the partition plate with the second intake passage interposed therebetween.

The present disclosure provides air intake ports and/or intake manifolds having an altered configuration to improve the efficiency of the air intake ports, intake manifolds, and by extension, the engine.

In an upstream portion from a valve connecting surface that is formed in an opening of an intake port to a combustion chamber, an upper wall surface of the intake port continues from an upstream side end of the valve connecting surface and extends substantially straight and diagonally with respect to a ceiling surface on the intake port side. In addition, a cross-sectional shape of the portion in the intake port in a direction perpendicular to an axial direction of the intake port is a flat shape with an axis in a transverse direction being a long axis.

A construction machine includes: a partition member partitioning an accommodation space in an engine compartment into a main chamber and an intake chamber while having an inter-chamber opening; a fan disposed in the main chamber to generate cooling air flowing through an air intake opening, the intake chamber, the inter-chamber opening, and the main chamber in this order by sucking air in the engine compartment in a suction direction; a duct joined to an outer wall to enclose the air intake opening and including an inner peripheral surface enclosing a duct passage leading to the air intake opening and an outer peripheral surface. The duct extends in a duct extension direction different from the suction direction of the fan, disposed in the intake chamber to define a duct surrounding space around the outer peripheral surface of the duct.

An engine intake air duct 1 has an intake portion 10 that extends along a first center line A, and a main duct portion 20 that extends along a second center line B. The main duct portion 20 has a merging portion 50, a discharge opening 21, and an extending portion 40 that extends from the merging portion 50 towards an opposite end to the discharge opening 20. A reflecting wall 41 is provided at an end face of the extending portion 40. The intake portion 10 merges with the main duct portion 20 in such a way that the first center line A is directed towards a downstream end of the main duct portion 20.

To provide an engine device with high reliability and high safety in which a pipe conduit in a portion where a blow-by gas having leaked from a combustion chamber is merged with intake air (outdoor air) is not blocked with ice coating even in use in a cold region, especially an arctic region at 20 C. or less, a blow-by gas mixed joint configured to introduce a blow-by gas flowing in a returning hose to an intake pipe includes a blow-by gas guide plate that defines introduction space expanding upstream and downstream of a blow-by gas inlet in an intake direction of an intake passage. The blow-by gas guide plate closes an upstream end of a part of the introduction space expanding upstream of a blow-by gas inlet and opens a downstream end of a part of the introduction space expanding downward of the blow-by gas inlet in the intake passage.

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 bending 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 inclined portion which is inclined at a predetermined angle from the auxiliary extension portion toward the center of the cylinder and inclined at a predetermined angle downward toward the cylinder; an auxiliary vertical portion bending downward from the auxiliary inclined portion; and an auxiliary intake air outlet at an end portion of the auxiliary vertical portion.

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.

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).

Disclosed is an intake joint structure capable of blocking backflow of lubricating oil 18 at a connection position between an air inlet 12 of a turbocharger and a suction pipe 24. A backflow-preventive plate 25 is integrally molded to have a cylindrical portion 25a fitted over the air inlet 12 and a tapered portion 25b curved inward from an upstream end of the cylindrical portion 25a and converged downstream to provide an open end. A downstream end 24a of a suction pipe 24 is molded by soft material over a predetermined range using exchange blow molding. The cylindrical portion 25a of the backflow-preventive plate 25 is fitted over the air inlet 12 through a grommet 26 (first soft layer) and the downstream end 24a of the suction pipe 24 is fitted over the cylindrical portion 25a and is banded by a hose band 27.