FR3048731A1 - EXHAUST GAS RECIRCULATION SYSTEM OF A HEAT ENGINE - Google Patents

Abstract

The invention relates mainly to a system (23) for recirculating the exhaust gases of a heat engine comprising: a heat exchanger (14), called an EGR exchanger, comprising a body (13) containing: cooling formed by a set of tubes in which are able to circulate said exhaust gas, and - an exhaust gas bypass line allowing the gas to bypass said cooling device, characterized in that said system (23) comprises in addition a short-circuit conduit (38) allowing a coolant to bypass a radiator of the engine, said short-circuit conduit (38) being integrated with said body (13) of the exchanger (14) .

Description

EXHAUST GAS RECIRCULATION SYSTEM OF A HEAT ENGINE

The present invention relates to a system for recirculating the exhaust gas of a heat engine. The invention finds a particularly advantageous application in the field of motor vehicles.

In an internal combustion engine, the four stages of the thermodynamic cycle - admission of fuel gas and air, compression of the gas mixture, expansion due to the explosion of the mixture, exhaust - take place successively in the enclosures of the cylinders of the engine, said combustion chambers. The gases introduced into these combustion chambers consist on the one hand of air and on the other hand of gasoline or gas oil, in proportions proportionally dosed according to the engines and ignition systems used. The gas mixture is then ignited in the combustion chamber.

[0003] The exhaust gases of internal combustion engines fitted to most motor vehicles contain a certain number of pollutants which it is desirable to reduce the discharges into the atmosphere (in particular nitrogen oxides, carbon monoxide, unburned hydrocarbons, particulates and carbon dioxide). The regulations applicable to pollution by motor vehicles regularly lower the limits of acceptable discharges.

A large part of the pollutants generated by an internal combustion engine is due to incomplete combustion of the fuel. To reduce the pollutant discharges entering the exhaust line, it is known to use an EGR (acronym for "Exhaust Gas Recirculation") to recirculate a portion of the exhaust gas to the pipe of intake of the engine.

This EGR type system comprises a heat exchanger, said EGR exchanger, comprising a cooling device formed by a set of tubes in which are able to circulate the exhaust gas, and a bypass line of the gases exhaust system allowing the gas to bypass the cooling device. An EGR valve is used to manage the amount of exhaust gas re-injected at the intake. In addition, a flap manages the amount of exhaust gas flowing in the cooling device and the amount of gas passing through the bypass pipe.

The invention aims to optimize the configuration of such a system by proposing a recirculation system of the exhaust gas of a heat engine comprising: - a heat exchanger, said EGR exchanger, comprising a body containing: - a cooling device formed by a set of tubes in which the exhaust gases are able to circulate, and - an exhaust gas bypass duct allowing the gas to bypass the cooling device, such that the system comprises in addition, a short-circuit conduit allowing a coolant to bypass a heat engine radiator, the short-circuit conduct being integrated into the body of the exchanger.

By "integrated" is meant that the short-circuit conduit is integral with the body of the exchanger, so that the short-circuit conduct and the body of the exchanger form one and the same. room.

The invention thus allows, by integrating the short-circuit conduit to the body of the exchanger, to reduce the size and simplify the assembly of the short-circuit function of the heat engine radiator during a temperature rise phase of the latter.

In one embodiment, the exchanger and the short-circuit conduit have a common wall.

According to one embodiment, a coolant outlet of the heat exchanger is constituted by a through opening formed in the common wall and opening into the short-circuit conduit. Due to the recovery of the liquid heated by the exhaust gas, such a configuration accelerates the rise in temperature of the engine.

In one embodiment, the system further comprises a valve adapted to manage a quantity of exhaust gas passing through the exchanger.

In one embodiment, the valve is associated with a coolant inlet and a coolant outlet connected to the short-circuit conduit via a stitching.

According to one embodiment, the system comprises a control device comprising an electric motor associated with a flap carried by an axis rotatably mounted relative to the body, the flap being adapted to direct, according to its angular positioning, the exhaust gas. to the exhaust gas bypass line or to the cooling device.

The invention also relates to a heat engine comprising an exhaust gas recirculation system as defined above.

The invention also relates to a vehicle, including a motor vehicle, comprising the engine described above.

The invention will be better understood on reading the description which follows and the examination of the figures that accompany it. These figures are given for illustrative but not limiting of the invention.

Figure 1 is a schematic representation of a thermal engine architecture equipped with the exhaust gas recirculation system according to the present invention; [0018] Figure 2 is a perspective view of the exhaust gas recirculation system according to the present invention; Figure 3 is a cross-sectional view of the exchanger according to the present invention and the associated short circuit conduit in which circulates the cooling liquid bypassing the heat engine radiator; Figure 4 is a perspective view in section of the exhaust gas recirculation system according to the present invention illustrating the communication between the short circuit conduit and the interior of the volume of the exchanger; Figure 5 is a perspective view of the exhaust gas recirculation system according to the present invention without the body of the exchanger; Figures 6a and 6b are cross sectional views of the exchanger and the short-circuit conduit according to the present invention respectively illustrating the positioning of an inlet and a coolant outlet of the exchanger.

Identical elements, similar, or the like retain the same reference from one figure to another.

[0024] Figure 1 shows an architecture 1 comprising an internal combustion engine 5 supercharged by a turbocharger 2 comprising a compressor 3 and a turbine 4. The compressor 3 compresses the intake air to optimize the filling of engine cylinders 5. For this purpose, the compressor 3 is disposed on an intake pipe 8 upstream of the engine 5. The flow of the exhaust gas drives in rotation the turbine 4 disposed on an exhaust pipe 9, which then rotates the compressor 3 via a coupling shaft. A turbocharger control valve 2 located upstream of the turbine 4 makes it possible to manage the quantity of exhaust gas flowing through the turbine 4 and the quantity of gas passing through a discharge pipe 16.

In order to maintain the density of the air acquired at the outlet of the compressor 3, a heat exchanger 10 called RAS (for cooling air cooler) is used to cool the air flowing in the duct. intake 8. The exchanger 10 is mounted downstream of the compressor 3 and upstream of an air metering device 18.

Furthermore, a system 23 for recirculating exhaust gas (called "EGR" for "Exhaust Gas Recirculation" in English) establishes a communication of an exhaust manifold 20 with the intake pipe 8 , and a heat exchanger 14, said EGR exchanger, exhaust gas. An EGR valve 25 makes it possible to manage the quantity of exhaust gas reinjected at the inlet. In addition, a flap 12 associated with an electric actuator 19 is adapted to manage the amount of exhaust gas flowing in a cooling device 34 and in a branch line 21, as is described in more detail below.

Thus, a portion of the exhaust gas of the engine 5 is rejected to the outside of the motor vehicle through the exhaust pipe 9 and another part of the gas is recycled. The quantity of gas to be recirculated is controlled by the EGR valve 25, which under given circumstances can be closed and leave nothing to re-circulate, for example in the case of a situation of maximum power of the engine 5.

More specifically, as shown in Figure 2, the EGR exchanger 14 comprises a body 13 provided at its ends with an input interface 30 in communication with the exhaust manifold 20 of the motor vehicle via the EGR valve 25 as well as an output interface 31 in communication with the intake pipe 8 of the heat engine 5. In order to ensure its cooling, the valve 25 is associated with an inlet 32 of coolant and with an outlet 33 of coolant connected to the short-circuit conduit 38 via a stitching 42.

As can be seen clearly in Figures 3, 4, 6a and 6b, the body 13 of the exchanger 14 defines a volume filled with coolant. The body 13 contains a cooling device 34 formed by a set of tubes 35 in which are able to circulate the exhaust gas. The body 13 also contains the bypass line 21 of the exhaust gases allowing the gas to bypass the cooling device 34.

The system 23 further comprises a short-circuit line 38 short-circuiting a heat sink 17 of the engine 5. In fact, during a start of the engine 5, the line 38 bypasses the radiator 17 of the engine. thermal engine 5 until the engine 5 reaches its operating temperature. Thus, as long as this temperature is not reached, a thermostat 19 remains closed so that the coolant flows through the short-circuit conduit 38 to loop directly to a water pump 22 located on the accessory facade of the vehicle . Once the operating temperature is reached, the thermostat 19 is opened to allow circulation of the coolant inside the radiator 17.

As can be seen in FIGS. 3 and 4, the short-circuit conductor 38 is integrated in the body 13 of the exchanger 14. By "integrated" is meant that the short-circuit conduit 38 is integral with the body 13 of the exchanger 14, so that the short-circuit conduit 38 and the body 13 of the exchanger 14 form a single piece. The short-circuit conduit 38 and the body 13 of the exchanger 14 may be made of the same material. The assembly can then be easily obtained by molding for example. Alternatively, the short-circuit conduit 38 is made of a material different from that of the body 13 of the exchanger 14. The body 13 and the short-circuit conduit 38 may be made of metal and / or a plastic material , the choice of material depending on the application. Preferably, the exchanger 14 and the short-circuit conduit 38 have a common wall 39, which makes it possible to minimize the bulk of the assembly.

The exchanger 14 is supplied with cooling liquid via an inlet 36 of liquid clearly visible in Figure 6a. The outlet 37 of coolant is constituted by a through opening made in the common wall 39 and opening into the short-circuit conduit 38, as can be seen in FIGS. 4 and 6b. This establishes a fluid communication between the internal volume of the exchanger 14 and the short-circuit conduit 38. Due to the recovery of the liquid heated by the exhaust gas in the short-circuit conduit 38, such a configuration accelerates the temperature rise of the heat engine 5.

As shown in Figures 4 and 5, the system 23 also comprises a control device 24 comprising an electric motor 6 associated with the flap 12. The flap 12 is carried by an axis 40 rotatably mounted relative to the body 13 and is able to direct, according to its angular positioning, the exhaust gas to the bypass line 21 of the exhaust gas or to the cooling device 34.

The short-circuit conduit 38 is further connected to a manifold 43 via a pipe 44. For this purpose, the short-circuit conduit 38 comprises at each of its ends a connection interface 46 with a corresponding flexible hose 44.

The invention thus makes it possible, by integrating the short-circuiting line 38 to the body 13 of the exchanger 14, to reduce the size and to simplify the assembly of the short-circuit function of the heat engine radiator 17. 5 during a phase of temperature rise of the latter.

Claims (8)

1. System (23) for recirculating the exhaust gases of a heat engine (5) comprising: - a heat exchanger (14), called an EGR exchanger, comprising a body (13) containing: - a cooling device ( 34) formed by a set of tubes (35) in which said exhaust gases are able to circulate, and - an exhaust gas bypass line (21) allowing the gases to bypass said cooling device (34). ), characterized in that said system (23) further comprises a short-circuit conduit (38) allowing a coolant to bypass a radiator (17) of the engine (5), said driving short-circuit circuit (38) being integrated with said body (13) of the exchanger (14). 2. System according to claim 1, characterized in that said exchanger (14) and said short-circuit conduit (38) have a common wall (39). 3. System according to claim 2, characterized in that an outlet (37) of the cooling liquid of said exchanger (14) is constituted by a through opening made in the common wall (39) and opening into said short circuit conduit. (38). 4. System according to any one of claims 1 to 3, characterized in that said system (23) further comprises a valve (25) adapted to manage a quantity of exhaust gas passing through said exchanger (14). 5. System according to claim 4, characterized in that said valve (25) is associated with a coolant inlet (32) and an outlet (33) of coolant connected to said short-circuit conduit (38). ) via a stitching (42). 6. System according to any one of claims 1 to 5, characterized in that said system (23) comprises a control device (24) comprising an electric motor (6) associated with a flap (12) carried by an axis ( 40) rotatably mounted relative to the body (13), said flap (12) being adapted to direct, according to its angular positioning, the exhaust gases to said bypass line (21) of the exhaust gas or to said device. cooling (34). 7. A heat engine (5) comprising an exhaust gas recirculation system (23) as defined in any one of the preceding claims. 8. Vehicle, especially a motor vehicle, comprising the engine (5) according to the preceding claim.