EP3134635A1 - Intake manifold for an internal combustion engine of a motor vehicle - Google Patents

Abstract

The invention relates to a metal air intake manifold (10) for supplying the cylinders of an internal combustion engine with air, said intake manifold (10) having an outer opening (14) which is intended to be connected to a pipe (12) for recirculating exhaust gases emitted by the engine, said outer opening (14) communicating with a passage (16) through a wall (18, 18') of said intake manifold (10) and leading into the inside of said manifold, characterised in that said passage (16) is shaped in order to distribute a gas from the outer opening (14) towards the inside of said intake manifold (10), said passage (16) having a portion (16a), the cross-section of which continuously decreases from the outer opening (14) to a narrowed cross-section (20) which is shaped in order to direct a gas circulating in said passage (16) in the direction of the cylinders of the engine to which cylinders said intake manifold is connected.

Description

 INTAKE MANIFOLD FOR AN INTERNAL COMBUSTION ENGINE OF A MOTOR VEHICLE

The invention relates to an intake manifold for an internal combustion engine of a motor vehicle.

 An intake manifold, also called tundish, has the function of providing, to each engine cylinder, the amount of air necessary for complete combustion of the fuel.

 Some engines are equipped with exhaust gas recirculation (EGR), which lowers the oxygen content in the fuel air mixture. In general, these recycled exhaust gases are fed to the intake manifold by a metal conduit opening into the intake manifold. In the latter, the diffusion of the recycled exhaust gas with the fresh air coming from the air filter is obtained by a gas diffuser, generally disposed at the junction between the recycled exhaust gas supply line and the intake manifold. In some engines, the intake manifold is made of polymer material and the diffuser is a metal insert, for example stainless steel. This metal diffuser is comprised of a frustoconical portion whose end of larger diameter is connected to the EGR pipe and the end of smaller diameter is connected to a cylindrical portion which projects into the intake manifold. The free end of the cylindrical portion, located substantially in the center of the intake manifold, has lateral openings for the diffusion of gases. This arrangement makes it possible to prevent the exhaust gases from being in direct contact with the polymeric material constituting the intake manifold, thus protecting the walls thereof from the heat of the EGRs. However, the diffusion is not always optimal. In addition, this diffuser is generally welded to the mouth of the exhaust gas supply pipe. There is thus a risk of disconnection of the diffuser and the fall of the latter inside the intake manifold, likely to disrupt the operation of the engine and damage it. Finally, such a diffuser in metallic material is relatively expensive to produce.

There is therefore a need to improve the diffusion of EGR gases inside an intake manifold, in particular by making it safer and at a lower cost. To this end, the invention relates to a metal air intake manifold for supplying air to the cylinders of an internal combustion engine, said intake manifold having an external opening intended to be connected to a recycling line. exhaust gas emitted by the engine, said external opening communicating with a passage passing through a wall of said intake manifold and opening inside the latter, characterized in that said passage is shaped to diffuse a gas coming from the external opening towards the inside of said intake manifold, said passage having a portion whose section decreases continuously from the external opening to a restricted section shaped to accelerate and direct a gas flowing in said passage towards the engine cylinders to which said intake manifold is connected. Thus, the passage forms a diffuser integrated in the air intake manifold. There is no more risk of separation of the diffuser of the intake manifold, thus reducing the risk of engine failure. In other words, the air intake manifold according to the invention has a diffuser made in one piece with the collector. This diffuser integrated into the wall of the intake manifold therefore does not include any portion protruding inwardly of the intake manifold from the wall of the latter, unlike the diffusers reported in the prior art. The arrangement according to the invention, however, allows a good diffusion of the EGR inside the intake manifold by choosing an appropriate form of the restricted section, the portion whose section decreases allowing the acceleration of gases. The intake manifold according to the invention can in particular be made simply by molding, for example aluminum.

 Advantageously and in a nonlimiting manner, the passage may have a portion of flared shape between the restricted section and an inner end of said passage. Such a flared shape makes it possible to improve the redirection of the gases passing through said passage towards the inside of the intake manifold, in particular towards the cylinders of the engine. This flared shape may extend from the restricted section or from a portion of constant section adjacent to the restricted section.

In particular, the portion of flared shape may have at least one shoulder, which may also promote the orientation of the gas flowing in said passage to the cylinders of the engine. In general, the shape of the portion whose section decreases continuously can be determined to allow an acceleration of the incoming gas, including sufficient to allow the diffusion of these gases. This determination is part of the knowledge of the person skilled in the art.

 Advantageously and in a nonlimiting manner, for a simpler embodiment, the portion whose section decreases continuously may have a frustoconical or substantially frustoconical, symmetrical or asymmetrical shape. A correct acceleration of the incoming gases can for example be obtained with an angle at the top of the frustoconical or substantially frustoconical shape of 15 ° to 35 °, preferably 20 ° to 30 °. This angle can however be adapted according to the shape of the intake manifold considered.

 Advantageously and in a nonlimiting manner, the restricted section may extend at least in part in a plane inclined with respect to a plane containing the external opening of the passage. This can make it possible to more effectively direct the gases circulating inside the passage to the cylinders to which the intake manifold is connected. Thus, for example, a portion of the restricted section that extends in an inclined plane may allow to direct the gas to a cylinder disposed at one end of the intake manifold, on the side where extends this inclined plane.

 The restricted section may further extend in part in a first plane for example parallel to the plane containing the external opening, and partly in at least one other plane inclined relative to the latter, depending on the orientation that the it is desired to give the incoming gases through the passage.

In order to improve the distribution of the gas flowing inside the passage towards the cylinders of the engine, the restricted section may have an oblong shape with rounded edges, for example chosen from an oval, an ellipse, a pear-like shape, a shape similar to a crescent, a shape having two parallel edges connected by rounded ends, a shape having two parallel edges connected by portions of a circle of diameter greater than the distance separating the parallel edges, a combination of one or more of these forms or any other oblong form. These oblong shapes may extend in one or more planes, as already mentioned. The restricted section may further have rounded indented shapes in the direction of at least one cylinder of the engine to which said intake manifold is connected. In particular, the restricted section may have a notched shape towards each cylinder of the engine, which may help to promote the distribution of the gas flowing in the passage to this cylinder.

 The invention also relates to an internal combustion engine comprising an air intake manifold according to the invention and an exhaust gas recirculation duct emitted by the engine, said duct being connected to said external opening of said exhaust manifold. air intake.

 The invention finally relates to a motor vehicle comprising an internal combustion engine according to the invention.

 The invention is now described with reference to the appended non-limiting drawings, in which:

 - Figure 1 is a top view of an air intake manifold according to one embodiment of the invention, connected to an exhaust gas recirculation pipe;

 - Figure 2 is a view similar to that of Figure 1, without the exhaust gas recirculation pipe;

 - Figure 3 is a sectional view along line AA of Figure 1;

FIG. 4 represents a perspective view from above of an intake manifold according to another embodiment;

 - Figure 5 shows a sectional view along the line AA of Figure 4;

 FIG. 6 represents an enlarged view from above of the external opening of the passage of FIG. 4;

 - Figure 7 is a view similar to Figure 6 wherein the restricted section has another shape.

 By substantially parallel, perpendicular means a direction deviating from at most ± 20 °, or even at most 10 ° or at most 5 ° of a direction parallel, perpendicular.

Figure 1 shows a metal air intake manifold for supplying air to the cylinders of an internal combustion engine. For this purpose, the intake manifold 10 has openings for connection to the cylinders. This intake manifold 10 is connected to a pipe 12 for recycling the exhaust gases emitted by the engine. This pipe 12 is also metallic.

 The intake manifold 10 thus has an external opening 14 (visible Figures 2 and 3) for the connection of the pipe 12 for recycling the exhaust gas. As can be seen in FIG. 3, this external opening 14 communicates with a passage 16 passing through a wall 18 of the intake manifold 10.

 According to the invention, the passage 16 is shaped to diffuse a gas coming from the external opening 14 towards the inside of the intake manifold 10. This passage 16 has in particular a portion 16a whose section decreases continuously since the external opening 14 to a restricted section 20. In other words, the portion 16a does not have portions of constant section between the outer opening 14 and the restricted section 20. This restricted section 20 is shaped to direct a gas flowing in the passage 16 towards the cylinders of the engine to which the intake manifold 10 is connected. In the example shown in Figures 1 to 3, the intake manifold 10 is connected to four cylinders (not shown).

 The portion 16a whose section decreases continuously accelerates the gas entering the passage 16, thus promoting their diffusion inside the intake manifold 10. The shape of the restricted section 20 will allow to direct the flow accelerated gas to the engine cylinders.

Note that in the example shown in Figures 1-3, the air intake manifold 10 has a passage 16, a portion 16b has a flared shape between the restricted section 20 and an inner end 17 of the passage 16, that is to say between the restricted section 20 and the inside of the intake manifold. This portion 16b of flared shape makes it possible to promote the direction of the accelerated gas flow following its passage through the first portion 16a throughout the volume of the intake manifold 10 and in particular towards the ends of the intake manifold 10 which are connected to engine cylinders. This portion 16b of flared shape may in particular have a shoulder 22 for directing the flow of gas to different directions within the intake manifold 10. In this example, the flared section portion 16b is not directly adjacent to the section restricted 20, but is adjacent to a portion 16c of constant section itself adjacent to the restricted section 20.

 The portion 16a of section whose section decreases continuously in the example of Figures 1 to 3 has a substantially frustoconical shape. The shape of the restricted section 20, visible in Figure 2, is substantially oval. It is thus elongated in shape, its ends being directed towards the farthest cylinders to which is connected the intake manifold. In other words, the length of the restricted section 20 of elongated shape extends substantially parallel to a line connecting inlet manifold connection openings to the engine cylinders.

 Here, the restricted section 20 extends substantially in a plane parallel to the plane containing the external opening 14.

 The embodiment shown in Figures 4 and 5 differs from the previous in that the intake manifold 10 'is intended to be connected to 3 cylinders. The same elements are designated by the same numerical references contiguous to a premium "'".

 In the embodiment shown in Figures 4 to 6, the portion 16 'a whose section decreases continuously is substantially frustoconical and asymmetrical (Figure 5). The shape of the restricted section 20 'differs from the shape of the restricted section of the previous embodiment in order to distribute the incoming gas through the EGR line (not shown) to the 3 cylinders to which the intake manifold 10' is connected. Thus, the restricted section 20 'is substantially pear-shaped (see FIGS. 4 and 6) and extends in two inclined planes with respect to each other, as can be seen in FIG. 4. The restricted section 20 thus presents two rounded indented shapes, one of which is larger on the inlet manifold side connected to two cylinders of the engine and the other of smaller radius on the inlet manifold side connected to the third cylinder of the engine.

 It is thus understood that the restricted section 20 'may have a variable shape depending on the shape of the intake manifold and the position of the engine cylinders connected to this intake manifold. It can thus have an oval, elliptical, crescent-shaped, pear-shaped shape, shaped like a bone (FIG.

It will be noted that in general, whatever the shape of the passage, the latter is made in a part of the wall of the collector intake which has a greater thickness to allow the fixing of the gas recirculation exhaust pipe.

 As shown in FIGS. 1 and 3, the exhaust gas recirculation duct 18 is conventionally fixed by a flange 24 and two screws 26 passing through the flange 24 and screwed into bores provided for this purpose of the collector. intake 10. A metal seal is disposed between the flange 24 and the intake manifold 10.

 The invention has the advantage of integrating into a single room the intake manifold and a diffuser of the recycled exhaust gas. This simplifies the mounting of the exhaust gas recirculation line on the intake manifold, but also to limit the risk of loss of the diffuser by uncoupling. In addition, the diffusion of gases is improved by the particular shape of the walls of the passage forming the diffuser.

Claims

A metal air intake manifold (10, 10 ') for supplying air to the cylinders of an internal combustion engine, said intake manifold (10, 10') having an external opening (14, 14 ') intended to be connected to an exhaust gas recirculation pipe (12) emitted by the engine, said external opening (14, 14') communicating with a passage (16, 16 ') passing through a wall (18, 18 ') of said inlet manifold (10, 10') and opening therethrough, characterized in that said passage (16, 16 ') is shaped to diffuse a gas from the external opening (14 14 ') inwardly of said intake manifold (10, 10'), said passage (16, 16 ') having a portion (16a, 16' a) whose section decreases continuously from the outer opening (14, 14 ') to a restricted section (20, 20') shaped to accelerate and direct a gas flowing in said passage (16, 16 ') towards the engine cylinders r to which said intake manifold is connected.  2. intake manifold (10, 10 ')) according to claim 1, characterized in that the passage (16, 16') has a portion (16b, 16¾) of flared shape between the restricted section (20 , 20 ') and an inner end (17, 17') of said passage.  3. intake manifold (10, 10 ') according to claim 2, characterized in that the portion (16b, 16¾) of flared shape has at least one shoulder (22, 22').  4. intake manifold (10, 10 ') according to any one of claims 1 to 3, characterized in that the portion (16a, 16' a) whose section decreases continuously has a frustoconical shape or substantially frustoconical, symmetrical or asymmetrical.  Air intake manifold (10, 10 ') according to one of Claims 1 to 4, characterized in that the restricted section (20, 20 ') extends at least in part in a plane inclined with respect to a plane containing the external opening (14, 14') of the passage. Air intake manifold (10, 10 ') according to any one of claims 1 to 5, characterized in that the restricted section (20, 20') has an oblong shape with rounded edges, for example chosen an oval, an ellipse, a pear-like shape, a crescent-like shape, a shape with two parallel edges connected by rounded ends, a shape having two parallel edges connected by portions of a circle of diameter greater than the distance separating the parallel edges, a combination of one or more of these forms or any other oblong shape.  Air intake manifold (10, 10 ') according to one of Claims 1 to 6, characterized in that the restricted section (20, 20') has rounded indented shapes in the direction of at least a cylinder of the engine to which said intake manifold is connected.  An internal combustion engine comprising an air intake manifold (10, 10 ')) according to any one of claims 1 to 7 and an exhaust gas recirculation pipe (12) emitted by the engine, said pipe being connected to said external opening (14, 14 ') of said air intake manifold.  9. Motor vehicle comprising an internal combustion engine according to claim 8.