Device for the intake of air into a cylinder of an internal combustion engine, in particular a direct injection diesel engine or a petrol engine, in which the flow of air at the intake is macroscopically separated into two flows, one contributing in particular to filling the cylinder, and the other contributing in particular to the swirl movement of the air in the cylinder, comprising at least one air intake duct or air/fuel mixture duct connecting the cylinder head of the engine to the intake zone in the cylinder comprising at least one intake valve box that is closed off by an intake valve, an internal separating wall that divides the intake duct into an upper part and a lower part, and progressively adjustable closing means mounted on at least one of the parts of the air intake duct or air/fuel mixture duct, characterized in that the orifice of a first part of the intake duct, intended for swirling the air or the mixture, which opens into the intake valve box at the point closest to the peripheral wall of the cylinder has a smaller cross section in the plane essentially perpendicular to the primary axis of the intake duct, compared to that (H R) of the orifice of the upper part of the intake duct, in that the orifice of the second part of the intake duct, intended for filling the cylinder, opens into the intake valve box closer to the primary axis of the cylinder, in that at least the orifice of the first part of the intake duct has a ramp arranged on the side of the orifice closest to the primary axis of the cylinder and oriented towards that side of the orifice that is furthest from the primary axis of the cylinder, and in that the first part of the intake duct and the ramp are shaped and arranged such that the power of the movement of the swirling, resulting from the only swirling flow in the cylinder in the absence of the filling flow, is much greater than the engine's real swirl requirement. at least one air intake duct or air/fuel mixture duct connecting the cylinder head of the engine to the intake zone in the cylinder comprising at least one intake valve box that is closed off by an intake valve, an internal separating wall that divides the intake duct into an upper part and a lower part, and progressively adjustable closing means mounted on at least one of the parts of the air intake duct or air/fuel mixture duct, characterized in that the orifice of a first part of the intake duct, intended for swirling the air or the mixture, which opens into the intake valve box at the point closest to the peripheral wall of the cylinder has a smaller cross section in the plane essentially perpendicular to the primary axis of the intake duct, compared to that (H R) of the orifice of the upper part of the intake duct, in that the orifice of the second part of the intake duct, intended for filling the cylinder, opens into the intake valve box closer to the primary axis of the cylinder, in that at least the orifice of the first part of the intake duct has a ramp arranged on the side of the orifice closest to the primary axis of the cylinder and oriented towards that side of the orifice that is furthest from the primary axis of the cylinder, and in that the first part of the intake duct and the ramp are shaped and arranged such that the power of the movement of the swirling, resulting from the only swirling flow in the cylinder in the absence of the filling flow, is much greater than the engine's real swirl requirement.