FR2788565A1 - INTAKE MANIFOLD INCLUDING MEANS OF CONNECTION TO AN EXHAUST GAS RECYCLING CIRCUIT - Google Patents

Abstract

The invention relates to an intake manifold (10) of a heat engine of a motor vehicle, comprising a tubular duct (12) for admission of fresh air which opens into a supply unit (14) of the cylinders, of which at the at least one supply outlet (16) is intended to be mounted opposite a supply duct of an engine cylinder head, and of the type in which an inlet tube (18) for recycled exhaust gases, opens radially into the tubular inlet duct (12), characterized in that a Venturi tube (26) is arranged coaxially in the tubular inlet duct (12), the upstream end (28) of the tube (26) ) of Venturi substantially coinciding with an upstream end (30) of the tubular inlet duct (12), and a downstream end (32) of the Venturi tube (26) or neck of the Venturi, being arranged downstream of the inlet tube (18) exhaust gases to delimit between the neck (32) of the Venturi and the inner wall (34) of the tubular duct (12) for air intake r fresh a suction zone (33) of the exhaust gases.

Description

"Intake manifold comprising means for connection to a circuit

  of exhaust gas recycling "

  The invention relates to an intake manifold.

  The invention relates more particularly to an intake manifold for supplying oxidant to a motor vehicle engine, of the type which comprises a tubular duct for admitting fresh air which opens into a cylinder supply unit comprising at least one supply outlet intended to be mounted opposite a corresponding supply duct formed in a cylinder head of the engine, and of the type in which an inlet tube for recycled exhaust gases, coming from a vehicle exhaust system, opens substantially radially into the

  tubular fresh air intake duct.

  Many types of exhaust manifolds are known. Among the manifolds intended to be assembled to an injection engine, that is to say the manifolds which have no connection to any member responsible for delivering fuel to the engine and which are only intended to supply the engine with oxidant , in particular in air, one has long known one-piece collectors in the general form of "air box" into which open at least one inlet pipe for recycled exhaust gases, coming from an exhaust circuit

  of the vehicle, to improve engine performance.

  Conventionally, in such a type of manifold, the exhaust gas inlet tube opens radially into a

  tubular intake manifold.

  This type of manifold is particularly advantageous in comparison with older intake systems, in which a simple intake manifold is coupled to an independent box responsible for ensuring the mixing of fresh air from the atmosphere and recycled exhaust gases. These collectors are indeed much more compact. However, it has been found that the mixture of fresh air and recycled exhaust gases is not very homogeneous because of the radial position of the exhaust gas inlet tube. This type of manifold does not ensure constant homogeneity whatever the rotation speed of the associated engine and the arrival of exhaust gas disturbs

  the main flow of fresh air.

  To overcome these drawbacks, the invention proposes a collector which makes it possible to ensure the constitution of a mixture

  s 5 homogeneous fresh air and recycled exhaust gases.

  To this end, the invention provides an exhaust manifold of the type described above, characterized in that a Venturi tube is arranged coaxially in the tubular fresh air intake duct, the upstream end of the Venturi tube substantially coinciding with an upstream end of the tubular fresh air intake duct, and in that a downstream end of the Venturi tube, or Venturi neck, is arranged downstream of the exhaust gas inlet tube for define a suction area between the neck of the Venturi and the inside wall of the tubular air intake duct

exhaust gases.

  According to other characteristics of the invention - the tubular fresh air intake duct is narrowed radially at the level of the Venturi neck to delimit axially, between the upstream end of the tubular fresh air intake duct and the Venturi neck, a peripheral chamber allowing the mixing of exhaust gases; -the peripheral chamber has inside a housing in which is attached the Venturi tube and which allows fixing by wedging the venturi tube during its assembly between the upstream end of the tubular conduit and a connection flange to a radiator of the vehicle; - The housing receives a flange formed at the upstream end of the Venturi tube; - The power supply is substantially parallelepipedal, the tubular duct for admitting fresh air io opening into its upper face, and its supply outlets opening into one of its lateral faces; - The power supply includes in at least one of its lateral faces holes made at regular intervals to allow its fixing by screwing on the cylinder head of the engine;

  - The intake manifold is made by molding.

  Other characteristics and advantages of the invention

  will appear on reading the detailed description which follows

  for the understanding of which reference will be made to the accompanying drawings in which: - Figure 1 is a sectional view along its median longitudinal plane of an intake manifold according to the invention; - Figure 2 is a perspective view of the assembly of a venturi tube in a manifold according to the invention and - Figure 3 is a cross-sectional view in a

  transverse median plane 3-3 of the intake manifold.

  In the description which follows, figures of

  identical reference designates identical parts or having

similar functions.

  FIG. 1 shows a set of an intake manifold 10 produced in accordance with the invention. In known manner, the intake manifold 10 comprises a tubular duct 12 for intake of fresh air which opens into a block 14, box-shaped, for supplying the cylinders which comprises supply outlets 16 intended to be mounted opposite a corresponding supply duct (not shown) made in a cylinder head (not

shown) of the engine.

  lo In the preferred embodiment of the invention, the intake manifold 10 has four supply outlets 16, but this arrangement is not restrictive of the invention and it could include a higher or lower number depending on whether '' it is an engine with more or less cylinders or an engine with several

intake valves per cylinder.

  The intake manifold 10 is conventionally made-

  by molding, which advantageously allows

  obtain it at low manufacturing costs.

  n0 In known manner, the intake manifold 10 comprises an inlet tube 18 of recycled exhaust gases, the trace of which is seen in dotted lines in FIG. 1 and which can be seen in the perspective view of the figure. 2. The inlet pipe 18 for recycled exhaust gas is arranged radially with respect to the axial direction of the tubular duct 12 for admission of fresh air so as to allow a mixture of the fresh air coming from the atmosphere and exhaust gases from an exhaust circuit (not shown) of the vehicle, in order to improve the efficiency of the engine during

operation.

  In the preferred embodiment of the invention, the supply unit 14 for the cylinders is of substantially parallelepipedal shape and comprises on an upper face 20 an orifice 22 which coincides with a downstream end 24 of the tubular inlet duct 12 fresh air which extends axially parallel to the longitudinal direction of the supply unit 14. According to the invention, a Venturi tube 26 is arranged coaxially in the tubular duct 12 for fresh air intake. An upstream end 28 of the Venturi tube 26 substantially coincides with an upstream end 30 of the tubular duct 12 for intake of fresh air, and a downstream end 32 of the venturi tube 26, also called throat 32 of the Venturi, is arranged in downstream of the exhaust gas inlet tube 18 to delimit between the neck 32 of the Venturi and a wall 34 of the tubular conduit 12 an annular zone 33 for suction of

exhaust gas.

  To carry out a suction of exhaust gases using air from the atmosphere, the tubular duct 12 for fresh air intake is, in a transverse plane P located axially at the neck 32 of the Venturi, narrowed to a diameter slightly greater than the outside diameter of the neck 32 of the Venturi. The difference in diameter between the neck 32 of the Venturi and the tubular duct 12 for admitting fresh air is at this level of the order of a few millimeters. In this way, the exhaust gas inlet tube 18 being located downstream of the exhaust gas suction zone 33, these are almost homogeneously mixed with the fresh air coming from the atmosphere before continuing their journey in the tubular duct 12 for fresh air intake in

direction of the admission block 14.

  The exhaust gases come out of the vehicle's exhaust system in volutes at a rate corresponding to the engine speed, and therefore non-uniformly. To harmonize the exhaust gas pressure, a peripheral chamber 36, visible in FIG. 1, is arranged coaxially with the Venturi tube 26 outside of it so as to delimit a buffer volume allowing at least partial expansion. recycled exhaust gases. This expansion favors their uniform mixing when these are sucked into the suction zone 33 by the fresh air coming from the atmosphere which passes through the venturi tube by creating a pressure difference to cause the suction in the zone.

0o 33.

  As illustrated in FIGS. 1 and 3, the supply unit comprises, in one of the side faces 54, the supply outlets 16 previously described, which are arranged opposite the supply conduits 56 of a

  cylinder head 58 of the associated thermal engine.

  According to the invention, at least one of the lateral faces of the supply unit 14 of the intake manifold, here the lateral face 54, has holes 60 intended to allow the passage of fixing screws 62 to fix the

  intake manifold 10 to the cylinder head 58 of the engine.

  In a preferred embodiment of the invention, a second lateral face 64 of the intake manifold 10 also has holes 66 which are intended to allow the passage of screws 68 which also pass through the lateral face 64 to allow the fixing of the collector

  supply 10 to the cylinder head 58 of the associated thermal engine.

  Finally, Figure 2 illustrates the particular assembly of the Venturi tube 26 between the upstream end 30 of the tubular conduit

  12 and a flange 31 for connection to the vehicle radiator.

  In this view, the end 30 of the tubular inlet duct 12 comprises a housing 70 in which the tube 26 from Venturi is received. The housing 70 has a groove 71 which receives an annular flange 72 which extends radially from the upstream end 28 of the Venturi tube (26). The groove 71 of the housing 70 is substantially of dimensions corresponding to the collar 72 so as to immobilize transversely and axially the Venturi tube 26 between the upstream end 30 of the tubular conduit 12 and a flange 31 of

  connection to a vehicle radiator.

  The flange 31 for connection to the vehicle radiator is fixed to the end 30 of the tubular intake duct 12, for example by means of screws (not shown) which make it possible to exert an axial clamping force on the two transverse faces of the collar 72 of the Venturi tube 26, and of

  thus achieve a good seal.

  This sealing can advantageously be completed by a flat annular seal (not shown) matching the shape.

  of the collar 72 of the Venturi tube 26.

  Thus, the intake manifold 10 as shown, consists of three easy assembly parts, which guarantees its low manufacturing cost and perfect tightness both

  n0 fresh air only with exhaust gas.

Claims (7)

  1. Intake manifold (10) for the supply of oxidant to a motor vehicle engine, of the type which comprises a tubular duct (12) for fresh air intake which opens into a power supply unit (14 ) cylinders comprising at least one supply outlet (16) intended to be mounted opposite a corresponding supply duct (56) formed in a cylinder head (58) of the engine, and of the 1st type in which a tube d inlet (18) of recycled exhaust gas, coming from an exhaust circuit of the vehicle, opens out, substantially radially into the tubular duct (12) for fresh air intake, characterized in that a tube ( 26) of Venturi is arranged coaxially in the tubular duct (12) for fresh air intake, the upstream end (28) of the tube (26) of Venturi substantially coinciding with an upstream end (30) of the tubular duct (12 ) fresh air intake, and in that a downstream end (32) of the Venturi tube (26), or neck (32) of the Venturi, is arranged downstream of the inlet tube (18) of the exhaust gases to delimit between the neck (32) of the Venturi and the inner wall (34) of the tubular duct (12) for fresh air intake a zoned   exhaust gas suction (33).   2. Intake manifold (10) according to the preceding claim, characterized in that the tubular duct (12) for fresh air intake is narrowed radially at the neck (32) of the Venturi to delimit axially, between the upstream end (30) of the tubular air intake duct and the neck (32) of the Venturi, a peripheral chamber (36) allowing the exhaust gas mixing.   3. Intake manifold (10) according to claim 2, characterized in that the peripheral chamber (36) has inside a housing (70) in which is attached the Venturi tube (26) and which allows fixing by jamming the Venturi tube (26) during its assembly between the upstream end (30) of the tubular conduit (12) and a flange (31) for connection to a vehicle radiator. 4. Intake manifold (10) according to claim 3, characterized in that the housing (70) comprises at least one annular groove (71) in which is received a flange   (72) formed at the upstream end (28) of the Venturi tube (26).   5. Intake manifold (10) according to any one   of the preceding claims, characterized in that the block   (14) supply is substantially parallelepiped, the tubular duct (12) of fresh air intake opening in its upper face (20), and its supply outlets (16)   opening into one of its lateral faces (54).   6. Intake manifold (10) according to claim 5, characterized in that the supply block (14) comprises in at least one of its lateral faces (54, 64) holes (60, - 66) made at regular intervals to allow its fixing by screwing on the cylinder head (58) of the engine. 7. Intake manifold (10) according to any one   of the preceding claims, characterized in that it is produced by molding.