EP2553232B1 - Cooling device for an engine exhaust gas recirculation circuit - Google Patents

Description

The present invention relates to a cooling device for an exhaust gas recirculation circuit of an engine, especially a motor vehicle. It also relates to a set of an exhaust gas recirculation circuit and such a cooling device. It also relates to an intake gas supply system for an engine, particularly a supercharged diesel engine, comprising an air supply circuit of said engine and such an assembly. Such a device is shown in FR 2915771 A1 .

Currently, it is known to take exhaust from an engine, to inject them into the intake of said engine, in order to reduce pollutant emissions. These gases are usually called recirculated exhaust gas or EGR for "Exhaust Gas Recirculated", according to their name in English. The flow of EGR to the inlet is controlled by a valve and cooled by a heat exchanger, called EGR exchanger.

Today, the EGR exchanger and the valve are integrated in the same cooling loop.

It has been found by the applicant that this poses numerous problems and the invention proposes to solve them.

For this, the invention relates to a cooling device for an exhaust gas recirculation circuit of an engine, in particular a motor vehicle, said circuit comprising a valve for controlling the circulation of said gas, said device comprising a heat exchanger heat exchanger, said EGR exchanger, intended to allow a heat exchange between the exhaust gas passing through said recirculation circuit and a cooling fluid, and means for cooling said valve.

According to the invention, said device comprises a cooling loop, said high temperature shaped so that said cooling means of the valve are traversed by a first fluid, and a second cooling loop, said low temperature, shaped for that the EGR exchanger is traversed by a second fluid, provided at a lower temperature than the first fluid.

By "loop" is meant together equipment, including exchangers, directly connected to each other or by hoses or equivalent, said equipment and hoses being traversed by the fluid flowing through the loop. In other words, said high and low temperature loops respectively integrate the cooling means of the EGR circulation control valve and the EGR exchanger.

This provides a solution to not penalize a single cooling loop and distribute the heat to dissipate in an optimized manner. It also reduces the risk of fouling and formation of condensates at the valve. In addition, by limiting the cooling of the EGR at the valve, it is possible to have EGR whose cooling is limited, in particular in the case of bi-passage of the EGR exchanger, which is of interest for starting the catalytic converters, used in the exhaust lines of the engine, for the depollution.

• lesdites boucles haute et basse températures comprennent chacune un échangeur de chaleur, dit radiateur de refroidissement, respectivement, haute et basse température, permettant un échange de chaleur entre un flux d'air ambiant et, respectivement, lesdits premier et second fluides,
• la boucle basse température comprend un refroidisseur d'air de suralimentation, ledit refroidisseur d'air permettant un échange de chaleur entre l'air parcourant un circuit d'alimentation en air du moteur et le fluide de ladite boucle basse température,
• le refroidisseur d'air de suralimentation, l'échangeur EGR et le radiateur basse température sont montés en série selon le sens d'écoulement du fluide dans la boucle basse température,
• la boucle haute température comprend un radiateur de chauffage, ladite boucle étant conformée pour permettre un échange de chaleur entre de l'air traversant ledit radiateur de chauffage et le premier fluide, sortant desdits moyens de refroidissement de la vanne, de façon à réchauffer l'air traversant ledit radiateur de chauffage.

According to different embodiments:

• said high and low temperature loops each comprise a heat exchanger, said cooling radiator, respectively, high and low temperature, allowing a heat exchange between a flow of ambient air and, respectively, said first and second fluids,
• the low temperature loop comprises a charge air cooler, said air cooler allowing a heat exchange between the air passing through an engine air supply circuit and the fluid of said low temperature loop,
• the charge air cooler, the EGR exchanger and the low-temperature radiator are connected in series according to the direction of flow of the fluid in the low temperature loop,
• the high temperature loop comprises a heating radiator, said loop being shaped to allow a heat exchange between air passing through said heating radiator and the first fluid leaving said cooling means of the valve, so as to heat the air passing through said heating radiator.

The invention also relates to an assembly of an exhaust gas recirculation circuit, comprising a valve for controlling the circulation of said gas, and a cooling device for said circuit, as mentioned above.

According to an exemplary embodiment, said valve comprises a body and said cooling means of the valve consist of ducts, formed in said body so as to allow the circulation of the first fluid in said valve.

The invention also relates to an intake gas supply device for an engine, particularly a supercharged diesel engine, comprising an air supply circuit of said engine and an assembly as described above, the circuit of recirculation of exhaust gas opening into said air supply circuit.

• ledit circuit d'alimentation en air comprend une vanne de contrôle de la circulation de l'air,
• ledit système comprend une turbo compresseur présentant une turbine entrainée par les gaz d'échappement du moteur et un compresseur, entrainé par ladite turbine, pour comprimer l'air circulant dans le circuit d'alimentation, ledit circuit de recirculation des gaz d'échappement prélevant les gaz d'échappement en amont de la turbine et les introduisant dans le circuit d'alimentation en air en aval du compresseur.

According to exemplary embodiments:

• said air supply circuit comprises a valve for controlling the circulation of air,
• said system comprises a turbo compressor having a turbine driven by the exhaust gas of the engine and a compressor, driven by said turbine, for compressing the air circulating in the supply circuit, said exhaust gas recirculation circuit sampling the exhaust gases upstream of the turbine and introducing them into the air supply circuit downstream of the compressor.

• les figures 1 et 2 illustrent respectivement, de façon schématique, un exemple de boucle haute et basse température d'un dispositif de refroidissement conforme à l'invention,
• la figure 3 illustre de façon schématique un exemple de système d'alimentation en gaz d'admission d'un véhicule, conforme à l'invention et associé au dispositif de refroidissement illustré aux figures 1 et 2.

The invention will be better understood in the light of the following description which is given only as an indication and which is not intended to limit it, accompanied by the appended drawings among which:

• the Figures 1 and 2 illustrate respectively, schematically, an example of high and low temperature loop of a cooling device according to the invention,
• the figure 3 illustrates schematically an example of an intake gas supply system of a vehicle, according to the invention and associated with the cooling device illustrated in FIGS. Figures 1 and 2 .

As illustrated in Figures 1 and 2 The invention relates to a cooling device for an exhaust gas recirculation circuit of an engine 1, in particular a heat engine, for example diesel engine, of a motor vehicle. As detailed below, said circuit comprises a valve 2 for controlling the circulation of said gas. Said valve 2 is provided, for example, to allow flow control of the EGR passing through said circuit.

The device according to the invention comprises a heat exchanger 3, called EGR exchanger, intended to allow a heat exchange between the exhaust gas passing through said recirculation circuit and a cooling fluid, and means 4 for cooling the exhaust gas. said valve 1 for controlling the flow of EGR.

According to the invention, said device comprises a cooling loop 5, referred to as high temperature, illustrated more precisely in FIG. figure 1 , traversed by a first fluid. It is shaped, for example, so as to cool said engine 1 and may include a cooling radiator 6, said high temperature cooling radiator, allowing a heat exchange between a flow of ambient air and said first fluid.

Said high temperature cooling loop further comprises, for example, a water outlet housing 7, a thermostat 8 and a pump 9. The water outlet housing 7 is mounted directly on the engine 1 and connected by a pipe 10 to the high temperature cooling radiator 6. A pipe 11 is provided between the high temperature cooling radiator 6 and an inlet 1a of said first fluid in the engine 1.

The pump 9 is provided on the pipe 11 connecting the high temperature cooling radiator 6 and the engine 1, and the thermostat 8 is provided on the pipe 10 connecting the water outlet housing 7 and the high temperature cooling radiator 6.

The pump 9 causes a flow of fluid through said engine 1 where the first fluid cools the engine by charging in calories. The first fluid then enters the water outlet housing 7 and, if the thermostat 8 is open, runs through the pipe 10 connecting the water outlet housing 7 and the high temperature cooling radiator 6. It then enters said high temperature cooling radiator 6 where it is cooled before returning to the engine through line 11 connecting the high temperature cooling radiator 6 and the engine 1.

The device according to the invention also comprises a second cooling loop 12, referred to as low temperature, detailed in FIG. figure 2 , traversed by a second fluid. Said low-temperature loop comprises, for example, a cooling radiator 13, said low-temperature cooling radiator, allowing a heat exchange between a flow of ambient air and the second fluid, provided flowing in said radiator.

According to the invention, said high temperature loop 5 is shaped so that said means 4 for cooling the EGR circulation control valve 2 are traversed by the first fluid and said second loop is shaped so that the EGR exchanger 3 is traveled by said second fluid, provided at a temperature lower than that of the first fluid.

This improves the overall operation of the device by assigning to the valve and the exchanger a separate cooling circuit from one another and may therefore be more appropriate.

Said first and second fluids are, for example, heat transfer fluids of the same chemical nature, such as water added with glycol.

According to the exemplary embodiment illustrated, said high and low temperature loops 5, 12 are independent and do not communicate with each other. However, it may be provided that said loops communicate with each other, in particular for the purpose of sharing the heat dissipation capabilities of the high and low temperature radiators 6, 13.

Said radiators 6, 13 high and low temperature are positioned relative to each other, for example so that they are crossed, in series, by the same air flow. In other words, they are placed one behind the other in the direction of flow of the air flow. However, they could also be arranged one below the other. They form, for example, a module that can be attached integrally, at the front of the vehicle.

If it returns to the high temperature loop 5, it may further include a bypass channel 14 of the high temperature radiator 6, connecting the water outlet housing 7 and the inlet 1a of the first fluid in the engine 1. Said bypass lane 14 is intended to be traversed by said first fluid when the thermostat 8 is closed, that is to say, when the engine 1 does not need to be cooled.

According to the illustrated embodiment, the high temperature loop 5 also comprises a heating radiator 15. This is, for example, a heating radiator of an air conditioning installation of the passenger compartment of the motor vehicle. Said loop 5 is shaped to allow a heat exchange between air passing through said heating radiator 15 and the first fluid leaving said cooling means 4 of the valve 2, so as to heat the air passing through said heating radiator .

According to the illustrated example, said high temperature loop 5 comprises a pipe 16, connecting, on the one hand, the inlet 1a of the first fluid in the engine and, on the other hand, an inlet of the first fluid in the valve 2 and an inlet of the first fluid in the heating radiator 15. It also comprises a pipe 17, connecting, on the one hand, an outlet of the first fluid of the valve 2 and an outlet of the first fluid of the heating radiator 15, and, On the other hand, the water outlet housing 7. In other words the valve 2 and the heating radiator 15 are placed in parallel in the direction of flow of the first fluid. The calories dissipated by the valve 2 in the circuit can thus reach the heating radiator 15, in particular by the bypass lane 14.

If we now return to the low temperature loop 12, it may include a low temperature pump 18 to ensure the circulation of the second fluid.

Said low temperature loop 12 furthermore comprises, for example, a charge air cooler 19. The latter is intended to allow a heat exchange between the air passing through an air supply circuit of the engine 1 and the fluid of the engine. said loop 12 low temperature.

According to the exemplary embodiment illustrated, the charge air cooler 19, the EGR exchanger 2 and the low-temperature radiator 13 are connected in series according to the direction of flow of the fluid in the low-temperature loop 12.

The invention also relates to an assembly of an exhaust gas recirculation circuit, comprising a valve 2 for controlling the circulation of said gas, and a cooling device for said circuit, as described above.

Said valve 2 comprises, for example, a body and said means 4 for cooling the valve 2 are constituted by pipes, not shown, formed in said body so as to allow the circulation of the first fluid in said valve 2.

As illustrated in figure 3 , the valve 2 and the EGR exchanger are connected in series, in that order, according to the direction of flow of the EGR.

Although this is not shown, it may be provided a pipe allowing the EGR to bypass the EGR exchanger, and a valve, said bypass, opening or closing said bypass pipe. For its cooling, said bypass valve may be integrated in said high temperature loop.

The invention also relates to an intake gas supply system for an engine, particularly a supercharged diesel engine.

Referring back to figure 3 it is found that said power system comprises a circuit 20 for supplying air to said motor and an assembly as described above. The gas recirculation circuit exhaust of said assembly, illustrated 21, opens into said air supply circuit 20, for example at a manifold 22 for distribution of the inlet gas in the engine 1.

Said air supply circuit comprises, for example, a valve 23 for controlling the flow of air, ensuring, in particular, a regulation of the air flow and / or participating in the regulation of the flow of EGR, in common with the valve 2 of the circuit 21 for recirculating the exhaust gas.

Said system may further comprise a turbo compressor 24 having a turbine 25, located in the path 26 for passing the exhaust gases from the engine 1 and driven by them, and a compressor 27, driven by said turbine 25, for compress the air circulating in the supply circuit. Said exhaust gas recirculation circuit 21 draws the exhaust gases upstream of the turbine 25 and introduces them into the air supply circuit 20 downstream of the compressor 27.

In said air supply circuit 20, the charge air cooler 19 and the air flow control valve 23 are provided, for example, in series, in this order, according to the direction of flow. air in said intake circuit 20, this between the turbine 27 and the injection point of the EGR in said supply circuit 20.

Claims (10)

1. A cooling device for an engine (1), notably motor vehicle engine, exhaust gas recirculation circuit (21), said circuit comprising a valve (2) for controlling the circulation of said gas, said device comprising a heat exchanger (3), known as an EGR exchanger, intended to allow an exchange of heat between the exhaust gases passing through said recirculation circuit (21) and a cooling fluid, and means (4) for cooling said valve, characterized in that said device comprises a cooling loop (5), known as a high-temperature loop, configured so that said valve cooling means (4) have a first fluid passing through them and a second cooling loop (12), known as a low-temperature loop, configured so that a second fluid, intended to be at a temperature lower than that of the first fluid, passes through the EGR exchanger (3).
2. The device as claimed in claim 1, in which said high-temperature and low-temperature loops (5, 12) each comprise a heat exchanger (6, 13) known respectively as a high-temperature and a low-temperature cooling radiator, allowing an exchange of heat between a stream of ambient air and, respectively, said first and second fluids.
3. The device as claimed in claim 2, in which the low-temperature loop comprises an intercooler (19), said intercooler allowing an exchange of heat between the air that passes through an engine air supply circuit and the fluid of said low-temperature loop.
4. The device as claimed in claim 3, in which the intercooler (19), the EGR exchanger (3) and the low-temperature radiator (13) are mounted in series in the direction in which the fluid flows in the low-temperature loop.
5. The device as claimed in any one of the preceding claims, in which the high-temperature loop comprises a heating radiator (15), said loop being configured to allow an exchange of heat between air passing through said heating radiator (15) and the first fluid leaving said valve cooling means (4), so as to heat up the air that passes through said heating radiator.
6. An assembly of an exhaust gas recirculation circuit (21) comprising a valve (2) for controlling the circulation of said gas, and of a device for cooling said circuit, as claimed in any one of the preceding claims.
7. The assembly as claimed in claim 6, in which said valve (2) comprises a body and said means (4) of cooling the valve (2) consist of ducts, formed in said body so as to allow the first fluid to flow through said valve.
8. A system for supplying an engine, notably a supercharged diesel engine, with inlet gas, comprising a circuit (10) for supplying said engine with air and an assembly as claimed in either one of claims 6 and 7, the exhaust gas recirculation circuit (21) opening into said air supply circuit (20).
9. The system as claimed in claim 8, in which said air supply circuit comprises a valve (23) for controlling the circulation of the air.
10. The system as claimed in either one of claims 8 and 9, comprising a turbocharger (24) having a turbine (25) driven by the exhaust gases from the engine, and a compressor (27) driven by said turbine (25) to compress the air flowing through the supply circuit (20), said exhaust gas recirculation circuit (21) bleeding exhaust gases off upstream of the turbine (25) and introducing them into the air supply circuit downstream of the compressor (27).

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