Intake manifold

#The invention relates generally to an intake manifold for a combustion engine of the type comprising a dimensionally stable induction pipe body having at least one flow-through opening and at least one first adjusting element being arranged in the first flow-through opening to vary the cross-sectional area through which an air/fuel mixture can pass. This adjusting element typically is a throttle valve, which is rotatably supported in the induction pipe body and which is capable of being urged to sealingly engage with the boundary wall of the first flow-through opening.

#Such types of intake manifolds are generally known. However, in many of the known intake manifolds, the engine output of the combustion engine is diminished by a return flow of air-fuel mixture from the combustion chamber back into the intake manifold. Because of piston travel and valve overlap, such a return flow in the intake manifold occurs with greater intensity in the low speed range, when the force of the gas flow is relatively small.

#There remains a need for the further development of an intake manifold in which the air-fuel mixture is prevented from flowing back into the intake manifold of the combustion engine, and in which resistance to flow in the direction of the combustion engine is not significantly increased by the intake manifold at high engine speeds.

#Other characteristics of the invention appear from the following detailed description and from the accompanying drawings, in which:

#FIG. 1 is a longitudinally sectional view of a first embodiment of an intake manifold constructed according to the principles of the invention;

#FIG. 2 depicts the intake manifold of FIG. 1 as viewed from the combustion engine; and

#FIGS. 1 and 2 show an intake manifold for a combustion engine, the induction pipe body 1 being constructed of polymer material and having first and second flow-through openings 2 and 6, which are each provided with adjusting elements 3 and 7, respectively, to alter an associated cross-sectional area of passage. The first adjusting element 3 is a throttle valve 5, which is secured to a throttle shaft and is supported by this shaft in the intake manifold. The second flow-through opening 6 is formed by a cage 9 of a one-way valve 8, which as a non-return valve can only be traversed by flow in the direction of the combustion engine. The second flow-through openings 6 are formed as perforations 10 in the cage 9, the perforations 10 being designed to serve as a valve seat 12 that can be forcibly engaged with the elastomeric sealing members 11.

#In FIG. 1, the intake manifold is flange-mounted directly on the cylinder head in the immediate vicinity of the intake valve of the combustion engine. The one-way valve 8 is secured to the front side of the induction pipe body 1 facing the combustion engine, the cage 9 with its inner circumference forming the boundary wall 4 of the first flow-through opening 2. The throttle valve is rotatably supported inside the induction pipe body 1. The sealing members 11 of the one-way valve 8, which in this exemplary embodiment are made of an elastomeric material, are each secured to the cage 9 in a gas-tight manner by a fastening element 11'.

#The second adjusting element 7 of FIG. 1 is further shown in FIG. 2. This illustrative embodiment provides for six second flow-through openings 6, which are distributed uniformly in the circumferential direction. In this embodiment, the combustion engine (not shown here) is operated in the low speed range, so that the air or the air-fuel mixture only flows through the second adjusting elements 7 and is fed to the combustion chambers. To prevent the mixture from flowing back as a result of the oscillating travel of the piston and the valve overlap of the combustion engine, the sealing members 11 are designed so that they can be forced automatically into the closed position, given a relative overpressure on the side facing the combustion engine.