FR2893988A1 - Internal combustion engine e.g. supercharged internal combustion engine, for use in vehicle, has inlet and exhaust pipes including respective necks configured to accelerate flow of gas and fresh air in exhaust and inlet pipes, respectively - Google Patents

Abstract

The engine has an inlet pipe (7) including a neck (71) that is formed by restriction of a passage section of an exhaust pipe (9), where the neck is configured to accelerate flow of exhaust gas in the exhaust pipe. The exhaust pipe has a neck (91) that is configured to accelerate the flow of fresh air in the inlet pipe. A recirculation pipe has two end parts, where one of the end parts includes a mouth section that extends transversally in the direction of an exhaust gas flow by being oriented opposite to the direction of circulation of the exhaust gas.

Description

TECHNICAL FIELD TO WHICH THE INVENTION RELATES The invention relates to

  generally the exhaust gas recirculation circuits. The invention relates more particularly to an internal combustion engine comprising an intake duct comprising a neck, an exhaust duct, an exhaust gas recirculation circuit comprising a recirculation duct, a first end portion of which opens into the exhaust duct. the exhaust pipe and a second end portion of which opens into the intake pipe at said neck.

  The invention finds a particularly advantageous application in the production of a diesel-type internal combustion engine. BACKGROUND OF THE INVENTION Diesel-type internal combustion engines generally comprise an exhaust gas recirculation circuit. This exhaust gas recirculation circuit makes it possible to take a part of the exhaust gas from the combustion circuit and to inject it back into the intake circuit in order to be burned down in order to reduce the pollutant emissions of the gases. exhaust. An internal combustion engine exhaust gas recirculation circuit generally includes an exhaust gas flow control valve. However, a control valve is a device whose mechanism is complex, which increases the production costs of the engine, and which clogs up quickly. In addition, the use of the control valve must be adapted to the pressure difference prevailing on the one hand in the exhaust circuit and on the other hand in the intake circuit to take the gas flow from exhaust to be burned corresponding to these pressure differences. OBJECT OF THE INVENTION The present invention proposes a new internal combustion engine comprising an exhaust gas recirculation circuit whose number of mechanical parts is limited. For this purpose, it is proposed according to the invention an internal combustion engine comprising an intake pipe comprising a neck, an exhaust pipe, an exhaust gas recirculation circuit comprising a recirculation pipe, a first part of which end opens into the exhaust pipe and a second end portion of which opens into the intake pipe at the level of said neck, in which the exhaust pipe also has a neck at which the first end portion opens of the recirculation line so as to take a part of the accelerated exhaust gas in said neck. Thanks to the arrangement of the neck of the exhaust pipe and the first end portion of the recirculation pipe of the engine according to the invention, part of the accelerated exhaust gas at the neck is removed without the intervention of additional mechanisms in the recirculation circuit. The higher the flow of the exhaust gas, the greater the flow of exhaust gas that has to be burnt off, in order to limit pollutant emissions. However, the exhaust gas sampling through the first end portion of the recirculation pipe opening at the neck of the exhaust pipe is, thanks to the arrangement of the neck and the first end portion of the recirculation line, proportional to the flow rate of the exhaust gas in the exhaust pipe.

  Thus, an increase in the flow of exhaust gas in the exhaust pipe causes an increase in the exhaust gas flow rate, and vice versa, which automatically regulates the exhaust gas sampling in the recirculation circuit. exhaust gas depending on the amount of exhaust gas to be burned.

  Finally, the number of mechanical parts of the recirculation circuit is limited which reduces the production costs of the engine. Other advantageous and non-limiting characteristics of the engine according to the invention are the following: the mouth section of the first end portion extends substantially transversely to the flow of exhaust gas while being oriented opposite flow direction of the exhaust gas flow. the first end portion of the recirculation pipe extends in the exhaust pipe substantially parallel to the axis of the neck of the exhaust pipe; - The mouth section of the first end portion is positioned at the center of the passage section of the exhaust pipe; - The mouth section of said second end portion extends substantially transversely to the fresh air flow of the intake pipe being oriented in the direction of flow of said fresh air flow; the second end portion of the recirculation duct extends in the intake duct substantially parallel to the axis of the neck of the intake duct; the mouth section of the second end portion is positioned at the center of the passage section of the intake duct; - the engine being provided with a turbine traversed by the exhaust pipe and a compressor traversed by the intake pipe, the neck of the intake pipe is located upstream of the compressor in the direction of gas flow cool and the neck of the exhaust pipe is located downstream of the turbine in the direction of flow of exhaust gas; - the engine being provided with a turbine traversed by the exhaust pipe and a compressor traversed by the intake pipe, the neck of the intake pipe is located downstream of the compressor in the direction of gas flow cool and the neck of the exhaust pipe is located upstream of the turbine in the direction of flow of exhaust gas; the neck of the exhaust pipe is situated downstream of a catalyst; the exhaust gas recirculation circuit comprises means for controlling the flow of exhaust gas flowing through the recirculation circuit; the means for controlling the flow of exhaust gas passing through the recirculation circuit comprise a butterfly flap intended to vary the passage section of the recirculation pipe; the exhaust gas recirculation circuit comprises means for cooling the flow of exhaust gas passing through the recirculation circuit.

  DETAILED DESCRIPTION OF AN EXEMPLARY EMBODIMENT The following description with reference to the appended drawing of an embodiment, given by way of non-limiting example, will make it clear what the invention consists of and how it can be achieved. In the accompanying drawing: - the single figure is a schematic view of a portion of the internal combustion engine according to the invention. In the single figure there is shown a portion of an internal combustion engine which comprises an intake circuit 10 and an exhaust circuit 20, and a recirculation circuit 8 of the exhaust gas. The exhaust circuit 20 comprises an exhaust manifold (not shown) connected to an exhaust pipe 9 equipped with a catalyst and a particulate filter (not shown). The intake circuit 10 comprises an intake distributor (not shown) and an intake duct 7.

  Here, the internal combustion engine is supercharged type. It comprises a compressor C traversed by the intake pipe 7 and a turbine T through which the exhaust pipe 9 passes. In a variant, the engine may be at atmospheric suction. The exhaust pipe comprises a neck 91, formed by a restriction of the passage section of the exhaust pipe 9 followed by an expansion of this passage section, intended to accelerate the flow of exhaust gas in the pipe Similarly, the intake pipe 7 comprises a neck 71 intended to accelerate the flow of fresh air 31 in the intake pipe 7.

  Preferably, the neck 91 of the exhaust pipe 9 is located downstream of the turbine T in the direction of flow of the exhaust gas and the neck 71 of the intake pipe 7 is located upstream of the compressor C in the direction of circulation of fresh air 31. The recirculation circuit 8 of the exhaust gas 8 comprises a pipe 89 comprising, in the direction of the flow of the exhaust gas, an upstream portion 85, cooling means 81 and a downstream portion 83. The upstream portion 85 of the pipe has a bend extended by a right end portion 86 which opens into the exhaust pipe 9 at the neck 91 of the exhaust pipe 9.

  In particular, the first end portion 86 of the right of the recirculation pipe 89 extends in the exhaust pipe substantially parallel to the axis of the neck 91 of the exhaust pipe 9 (or, parallel to the line average of this pipe) so that the mouth section 87 of this first end portion 86 extends transversely to the direction of the exhaust gas flow 32. The mouth section 87 of this first part of end 86 is oriented away from the direction of flow of the exhaust stream 32. Here, the mouth section 87 of the first end portion 86 is positioned at the center of the passage section of the pipe 9. Similarly, the downstream portion 83 of the recirculation pipe 89 has a prolonged elbow with a straight end portion 84 opening into the intake pipe 7, at the neck 71 of the intake pipe. 7.

  The second end portion 84 of the recirculation pipe 89 extends in the intake pipe 7 substantially parallel to the axis of the neck 71 of the intake pipe 7 (or, parallel to the average line of this pipe) so that the mouth section 88 of this second end portion 84 extends transversely to the direction of the fresh air flow 31 of the intake pipe 7. The mouth section 88 of this second end portion 84 is oriented in the flow direction of said fresh air flow 31. As for the first end portion 86, the mouth section 88 of the second end portion 84 is positioned at the center of the passage section of the intake pipe 7. Finally, there is provided a means for controlling the flow of the withdrawn portion 33 of the exhaust gas passing through the recirculation circuit 8 intended to vary the passage section of the pipe recirculation 89, here a butterfly flap 82. The operation of the engine according to the invention is as follows.

  The exhaust gases 32 from the combustion in the combustion chamber are discharged to the exhaust manifold (not shown) of the exhaust system 20, then, these exhaust gases 32 are conveyed by the exhaust pipe 9 and pass through the turbine T. Downstream of this turbine they are accelerated by the neck 91 of the exhaust pipe 9. During the passage of the exhaust gas 32 at the neck 91 of the exhaust pipe 9, a part 33 of these accelerated exhaust gas is taken by the first end portion 86 of the pipe 89 of the recirculation circuit 8. Thus, thanks to the arrangement of the neck 91 of the exhaust pipe 9 and the first end portion 86 of the recirculation line 89 of the engine according to the invention, a part of the accelerated exhaust gas at the neck 91 is removed without the intervention of additional mechanisms in the recirculation circuit. The throttle flap 82 regulates the flow rate of this part 33 taken from the exhaust gas in the recirculation line 89. Then this part 33 taken from the exhaust gas is cooled by the cooling means 81 and is conveyed by the downstream part 83. 89. The flow of fresh air taken by the intake pipe 7 into the atmosphere passes at the neck 71 of the intake pipe 7. This neck 71 of the intake pipe 7 drives the acceleration of the fresh air flow 31, which causes by the Venturi effect an aspiration of the withdrawn portion 33 of the exhaust gas of the recirculation circuit 8 and the withdrawn portion 33 of the exhaust gas opens into the duct intake 7 by the second end portion 84 of the downstream portion 83 of the recirculation line 89. This exhaust gas portion 33 is mixed with the fresh air 31 and then passes through the compressor C and is reinjected into the combustion chamber where this mixture is re-burned. The exhaust gas sampling by the first end portion 86 of the recirculation line 89 opening at the neck 91 of the exhaust pipe 89 is, thanks to the arrangement of the neck 91 and the first part of the end 86 of the recirculation pipe 89, proportional to the flow rate of these exhaust gases in the exhaust pipe 9. Thus, an increase in the flow of exhaust gas in the exhaust pipe 9 causes an increase in the flow rate of the withdrawn portion 33 of the exhaust gas and vice versa which automatically regulates the exhaust gas sampling in the recirculation circuit 8 of the exhaust gas according to the amount of exhaust gas to be burned. Alternatively, it can be provided that the first end portion of the recirculation pipe opens into the exhaust pipe with a non-zero inclination relative to the axis of the corresponding neck (or in relation to the average line of this pipe). driving), that is to say a non-zero inclination with respect to the direction of the flow of the exhaust gas.

  Similarly, it can be provided that the second end portion of the recirculation pipe opens into the intake pipe with a non-zero inclination relative to the axis of the corresponding neck. This results in a better mixing rate of the exhaust gas part with the fresh air. Alternatively, it can be provided that, on the one hand, the arrangement of the neck of the exhaust pipe with the first end portion of the recirculation pipe is carried out upstream of the turbine and, on the other hand, that the arrangement of the neck of the intake pipe with the second end portion of the recirculation pipe is made downstream of the compressor. It is then also possible to collect by means of the recirculation circuit a portion of the exhaust gas at the exhaust manifold and to reinject these exhaust gases at the inlet distributor. It can also be provided that the first end portion of the recirculation duct opening into the exhaust duct is not straight but, for example, in an arc of a circle, while maintaining a transverse opening cross section to the direction of flow of the duct. exhaust gas. This variant embodiment can also be applied to the arrangement of the second end portion of the recirculation pipe with the intake pipe.

  Finally, the arrangement, as described above, of the neck of the exhaust pipe and the neck of the intake pipe with the corresponding first and second end portions of the recirculation pipe can also be made to a non-supercharged engine.

Claims (13)

  An internal combustion engine comprising an intake duct (7) having a neck (71), an exhaust duct (9), an exhaust gas recirculation circuit (8) having a recirculation duct (89). ) of which a first end portion (86) opens into the exhaust pipe (9) and a second end portion (84) of which opens into the intake pipe (7) at the level of said neck (71), characterized in that the exhaust pipe (9) also has a neck (91) at which the first end portion (86) of the recirculation pipe (89) opens to withdraw a portion (33) of the exhaust gas (32) accelerated in said neck (91).   2. Motor according to the preceding claim, characterized in that the mouth section (87) of the first end portion (86) extends substantially transversely to the direction of the exhaust gas flow (32) being oriented opposite the direction of flow of the exhaust gas stream (32).   3. Motor according to one of the preceding claims, characterized in that the first end portion (86) of the recirculation pipe (89) extends in the exhaust pipe (9) substantially parallel to the axis of the neck (91) of the exhaust pipe (9).   4. Engine according to one of the preceding claims, characterized in that the mouth section (87) of the first end portion (86) is positioned at the center of the passage section of the exhaust pipe (9). ).   5. Motor according to one of the preceding claims, characterized in that the mouth section (88) of said second end portion (84) extends substantially transversely to the direction of the fresh air flow (31). the intake pipe (7) being oriented in the direction of flow of said fresh air flow (31).   6. Motor according to one of the preceding claims, characterized in that the second end portion (84) of the recirculation pipe (89) extends in the intake pipe (7) substantially parallel to the axis neck (71) of the intake pipe (7).   7. Motor according to one of the preceding claims, characterized in that the mouth section (88) of the second end portion (84) is positioned in the center of the passage section of the intake pipe (7). ).   8. Motor according to one of the preceding claims, characterized in that, the motor being provided with a turbine (T) traversed by the exhaust pipe (9) and a compressor (C) traversed by the pipe d inlet (7), the neck (71) of the intake duct (7) is located upstream of the compressor (C) in the direction of flow of the fresh gases (31) and the neck (91) of the duct exhaust (9) is located downstream of the turbine (T) in the direction of flow of the exhaust gas (32).   9. Motor according to one of claims 1 to 7, characterized in that, the motor being provided with a turbine (T) traversed by the exhaust pipe (9) and a compressor (C) traversed by the intake duct (7), the neck (71) of the intake duct (7) is situated downstream of the compressor (C) in the direction of circulation of the fresh gases (31) and the neck (91) of the exhaust pipe (9) is located upstream of the turbine (T) in the direction of flow of the exhaust gas (32).   10. Engine according to one of the preceding claims, characterized in that the neck (91) of the exhaust pipe (9) is located downstream of a catalyst.   11. Engine according to one of the preceding claims, characterized in that the recirculation circuit (8) of the exhaust gas comprises means for controlling (82) the flow of exhaust gas (33) through the recirculation circuit. (8).   12. Motor according to the preceding claim, characterized in that the control means (82) of the exhaust gas stream (33) passing through the recirculation circuit (8) comprise a butterfly flap (82) for varying the section. passing the recirculation line (89).   13. Engine according to one of the preceding claims, characterized in that the recirculation circuit (8) of the exhaust gas comprises cooling means (81) of the exhaust gas stream (33) passing through the recirculation circuit. (8).