FR2890697A1 - Vehicle engine has Exhaust Gas Recirculation (EGR) circuit equipped with supplementary cooler - Google Patents

Abstract

The engine (1), equipped with an EGR circuit, has a separate cooler for the EGR circuit that is supplementary to the engine cooler and in the form of a heat exchanger (7) that cools an EGR coolant fluid, a heat exchanger (6) between the coolant fluid and recirculated exhaust gases, and a pump (8) to circulate the fluid between the two heat exchangers. The two heat exchangers and the pump are connected in series to produce a coolant fluid circulation loop.

Description

2890697 1

  FIELD OF THE INVENTION The present invention relates to the field of the automobile, and more particularly to the field of engines comprising a recirculated exhaust gas circuit, operating with diesel or with gasoline.

STATE OF THE ART

  The environmental constraints relating to the exhaust emissions of a vehicle with an internal combustion engine, and in particular a diesel engine, are becoming more numerous. These environmental constraints aim in particular at reducing the amount of nitrogen oxides (NOx) contained in the exhaust gases.

  The production of nitrogen in the exhaust gas being strongly related to the temperature of the gas mixture introduced into the cylinders of the internal combustion engine of the vehicle, a solution for reducing the emissions of nitrogen oxides is therefore to act on the temperature of the introduced gas mixture. Since the amount of nitrogen oxides is greater when the temperature of the gas mixture is high, it will be necessary to reduce the temperature of the gas mixture supplied to the engine.

  In a vehicle engine comprising a recirculated exhaust gas circuit, the gas mixture supplying the engine comprises intake air and a certain amount of recirculated exhaust gas. These recirculated exhaust gases are commonly called EGR (EGR denoting the initials of Exhaust Gas Recirculation).

  Lowering the temperature of the EGR thus makes it possible to reduce the temperature of the gas mixture introduced into the engine, which reduces the production of nitrogen oxides by the same amount. Thus, to minimize the production of nitrogen oxides, the EGRs should be cooled to low temperatures. In addition, with such cooling at low temperatures, it will be possible to increase the rate of recycled gas.

  A known solution of the state of the art for reducing the temperature of the EGR is to use a heat exchanger between the EGR and the coolant of the engine cooling device (1), taken at the output of the engine or at the output of the engine. cooling radiator. Nevertheless, the reduction of the temperature of the EGR is limited, the stabilized temperature of the coolant during the use of the engine being indeed relatively high, of the order of 90 C.

  Another known solution is to use an EGR cooling circuit completely separate from the engine cooling device (1). Such a device for cooling the EGR can allow the circulation of a low temperature coolant and thus makes it possible to reduce the temperature of the EGR more significantly. However, this solution includes a number of cost and integration constraints within the engine compartment.

  EP 1 091 113 BI discloses a system for cooling EGR at two temperature levels. Indeed, the EGR cooling system comprises two heat exchangers, the first heat exchanger allowing a cooling of the EGR by a cooling liquid from a first cooling radiator, and the second exchanger allowing additional cooling of the EGR by the coolant from the radiator of the engine cooling device. However, in addition to the integration constraints, this EGR cooling system does not make it possible to obtain cooling of the EGR at low temperature, the cooling level being once again limited by the stabilized value of the temperature of the coolant. from the engine cooling device.

  An object of the present invention is therefore to provide an improved vehicle engine comprising a recirculated gas circuit cooled at low temperature. An object of the present invention is further to provide a vehicle engine to overcome at least one of the aforementioned drawbacks.

  SUMMARY OF THE INVENTION For this purpose there is provided according to the invention a vehicle engine comprising a cooling device of the engine and a recirculated gas cooling device separate from the engine cooling device, the engine being characterized in that the device gas cooling comprises means of additional cooling of the engine.

  Preferred but non-limiting aspects of the vehicle engine according to the invention are the following: the gas cooling device comprises a heat exchange means for cooling a gas cooling fluid, a heat exchange means between the gases and the gas cooling fluid, and a pump means for circulating the gas cooling fluid in the gas cooling device, connectable in series by fluid connection means so as to form a fluid circulation loop gas cooling; the engine cooling device comprises a heat exchange means for cooling an engine cooling fluid and a pump means for circulating the engine cooling fluid in the engine cooling device, the heat exchange means for cooling the engine cooling fluid and the pump means being connected in series by fluid connection means; the engine cooling device further comprises a control valve, which may be a thermostatic valve, adapted to regulate a flow rate of the engine cooling fluid between an output of the engine and the heat exchange means for cooling the cooling fluid of the motor; the additional engine cooling means comprise a first fluid connection means between the engine cooling device and the gas cooling device, a first engine coolant control valve, the first control valve being a three-way valve; pathways, possibly thermostatic, interposed in the engine cooling device, a second valve for regulating the gas cooling fluid, the second control valve being a three-way valve, optionally thermostatic, interposed in the gas cooling device, the first and second control valves being further interconnected by a second fluid connection means; the first fluid connection means connects an outlet of the pump means of the gas cooling device to an inlet of the pump means of the engine cooling device; the first control valve of the additional cooling means of the engine comprises an input and two outputs, the input being connected to the output of the motor, and the two outputs being respectively connected to an input of the control valve of the cooling device of the motor and an inlet of the second control valve of the additional cooling means of the engine; the second control valve of the additional cooling means of the motor comprises an output and two inputs, the output being connected to an input of the heat exchange means for cooling the cooling fluid of the gases, the inputs being respectively connected to an output of the pump means of the gas cooling device and at one of the outputs of the first control valve of the additional cooling means of the engine; the control valve of the engine cooling device is adapted to allow a passage of the engine cooling fluid from the outlet of the first control valve of the additional cooling means of the engine to the inlet of the heat exchange means for the engine. cooling the engine cooling fluid, from a first temperature, for example 89 C, the first control valve of the additional cooling means of the engine is adapted to allow a passage, the output of the motor to the input of the second control valve of the additional cooling means of the engine, from a second temperature, for example 95 C, and the second control valve of the additional cooling means of the engine is adapted to allow a passage, the output of the first control valve of the additional cooling means of the motor to the inlet of the heat exchange means for cooling the cooling fluid of the gases from a first temperature, for example 96 C; the second control valve of the additional cooling means of the engine may be an electric valve, and the gas cooling device comprises a temperature measuring means for measuring a temperature at the outlet of the second control valve of the cooling means additional engine, the second control valve of the additional cooling means of the engine being controlled according to the temperature measured by the temperature measuring means; the control valve of the engine cooling device is a three-way valve comprising an output connected to the second fluid connection means connecting the output of the first control valve to the inlet of the second control valve; the heat exchange means for cooling the gas cooling fluid is a cooling radiator, the pump means of the gas cooling device is an electric water pump, the heat exchange means for cooling the cooling fluid of the engine is a cooling radiator, and the pump means of the engine cooling device is a mechanical or electric water pump; the engine cooling device further comprises a degassing means connected in shunt of the heat exchange means for cooling the engine cooling fluid; the heat exchange means between the gases and a cooling fluid comprises an inlet and an outlet for the gases, and a fluidic inlet and outlet, the fluidic inlet being connected to the outlet of the heat exchange means for cooling the a gas cooling fluid and the fluidic outlet being connected to the inlet of the pump means of the gas cooling device; the heat exchange means between the gases and the cooling fluid may further comprise a fluidic inlet and outlet for the engine coolant, the inlet for the engine coolant being connected to the engine output and the outlet for the engine cooling fluid being connected to the inlet of the pump means of the engine cooling device; the engine comprises a heat exchange means between the engine coolant and air intended to be pulsed in a passenger compartment of the vehicle, the heat exchange means being connected on the one hand to the output of the engine and on the other hand at the inlet of the pump means of the engine cooling device; the engine further comprises a cooling fluid control valve and a first and a second fluid connection means, the control valve being interposed between the engine outlet and an inlet of the heat exchange means between the cooling fluid of the motor and the air circuit and further comprising an input connected to the output of the pump means of the gas cooling device, the first fluid connection means connecting an output of the heat exchange means between the engine coolant and the air circuit and an inlet of the heat exchange means between the gases and the gas coolant, and the second fluid connection means connecting the engine outlet to the inlet of the cooling device pump means. of the motor; According to the invention, a method for controlling a vehicle engine, comprising a recirculated gas circuit, is also provided, characterized in that the engine is cooled by an engine cooling device and the gases are cooled. by a gas cooling device separate from the engine cooling device, and the engine is also cooled by the gas cooling device.

  Preferred but non-limiting aspects of the vehicle engine control method according to the invention are as follows: the engine cooling device is controlled according to a temperature at an output of the engine; beyond a first threshold value of the temperature at the output of the engine, cooling a cooling fluid of the engine cooling device; the gas cooling device is controlled as a function of a temperature at an engine output and a temperature at an output of a heat exchange means of the gas cooling device between the gases and a cooling fluid of the gas; beyond a second threshold value of the temperature at the output of the engine, preferably greater than the first threshold value, the cooling fluid of the gases is directed towards the engine; below the first threshold value of the temperature at the output of the engine, the cooling fluid of the gas is directed to a heat exchange means for heating air intended to be pulsed in a passenger compartment of the vehicle.

DESCRIPTION OF THE FIGURES

  Other features and advantages of the invention will emerge from the description which follows, which is purely illustrative and nonlimiting and should be read with reference to the accompanying drawings, in which: - Figures 1a to 1c are schematic representations of a vehicle engine according to the invention, and the operation of the latter; Figures 2a and 2b illustrate the operation of a first control valve of the vehicle engine according to the invention; Figures 3a and 3b illustrate the operation of a second control valve of the vehicle engine according to the invention; Figure 4 is a schematic representation of the operation of the first and second control valves of Figures 2a-2b and Figures 3a-3b; Figure 5 is a schematic representation of a heat exchange means according to a first embodiment of the invention; FIG. 6 is a schematic representation of a heat exchange means according to a second embodiment of the invention. FIG. 7 is a schematic representation of the operation of the gaslfluid heat exchange means of FIG. 6; Figure 8 is a schematic representation of a vehicle engine according to the invention comprising the gaslfluid heat exchange means of Figure 6; Figure 9 is a schematic representation of a vehicle engine according to a third embodiment of the invention; Figure 10 is a schematic representation of a vehicle engine according to a fourth embodiment of the invention; Figure 11a is a schematic representation of a vehicle engine according to a fifth embodiment of the invention and Figure 11b illustrates the operation of the engine according to this fifth embodiment; Figure 12a is a schematic representation of a vehicle engine according to a sixth embodiment of the invention and Figure 12b illustrates the operation of the engine according to this sixth embodiment.

  DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION FIGS. 1a-1c show a vehicle engine according to a first embodiment of the invention.

  The engine 1 is an internal combustion engine of the diesel or gasoline type. This engine 1 comprises a recirculated gas circuit, the recirculated gas circuit is not shown in Figures la to lc.

  The engine 1 further comprises a cooling system. The cooling system includes an engine cooling device and a recirculated gas cooling device.

  The engine cooling device is a cooling device using a cooling fluid (FRM) for cooling the engine. This cooling fluid (FRM) may for example be a mixture of water and ethylene glycol with additional anti-corrosion agents.

  The engine cooling device comprises a heat exchange means 2 adapted to cool the engine cooling fluid (FRM) flowing through the engine cooling device. This heat exchange means 2 may for example be a cooling radiator.

  The engine cooling device further comprises a pump means 3 for circulating the engine coolant (FRM) through the engine cooling device. This pump means 3 will be for example a mechanical water pump driven by the engine 1. It is possible to also consider the use of an electric water pump.

  The engine 1, the cooling radiator 2, and the water pump 3 are arranged in series in the engine cooling device, and 30 are interconnected by means of fluidic connection means for circulating the engine cooling fluid. (FRM). The water pump 3 will for example be placed at the inlet of the engine 1.

  The engine cooling device further comprises a degassing means 4, such as an expansion vessel, placed in shunt of the cooling radiator 2. This degassing means 4 compensates for variations in the volume of the cooling fluid, and it also allows the pressurization of the engine cooling device.

  Further provided in the engine cooling device is a control valve 5 for regulating a flow rate of the engine coolant (FRM) between the output of the engine 1 and the cooling radiator 2. This control valve 5 is interposed in the engine cooling device at the output of the engine 1. The control valve 5 will for example be a thermostatic valve whose opening is a function of the temperature of the fluid flowing through it. Its opening start temperature may for example be about 89 C.

  The cooling system recirculated gas cooling device is designed to cool the recirculated gases and that they reach a relatively low temperature.

  The recirculated gas cooling device comprises a heat exchange means 6 of fluid / gas type. This heat exchange means 6 allows a heat exchange between the gases flowing in the recirculated gas circuit and a recirculated gas cooling fluid (FREGR) circulating in the recirculated gas cooling device.

  Such a heat exchange means 6 may therefore be for example an exchanger as illustrated in FIG. 5, comprising an inlet and an outlet for the recirculated gases and an inlet and an outlet for the recirculated gas cooling fluid (FREGR). .

  The cooling fluid used may be a conventional coolant, for example a mixture of water and ethylene glycol and anticorrosion agents.

  The recirculated gas cooling device further comprises a heat exchange means 7 for cooling the recirculated gas cooling fluid (FREGR) circulating in the recirculated gas cooling device. This heat exchange means 7 is designed to cool the recirculated gas cooling fluid (FREGR) at low temperature. In practice, it will take for example a heat exchange means 7 for cooling the cooling fluid so that it reaches temperatures below 150 C.

  The heat exchange means 7 may for example be a low temperature cooling radiator.

  The recirculated gas cooling device also comprises a pump means 8 for circulating the recirculated gas cooling fluid (FREGR) through the recirculated gas cooling device. This pump means 8 may for example be an electric water pump.

  Such a pump means 8 will preferably be interposed in the cooling device of the recirculated gases at the outlet of the exchanger 6.

  The fact of using an electric water pump 8 to circulate the recirculated gas cooling fluid (FREGR) makes it possible to cool the exchanger 6 even when the engine 1 is stopped, which would not be possible with a mechanical water pump driven by the same engine 1. However, when the engine 1 stops, the exchanger 6 is still very hot and a boiling phenomenon at its walls can take place at the stoppage of the flow recirculated gas cooling fluid (FREGR). This phenomenon can then deteriorate the metal wall of the exchanger 6 during the life of the vehicle. Thus, even when the engine 1 is stopped, the electric water pump 8 makes it possible to circulate the cooling fluid within the exchanger 6 and consequently to avoid the problem of boiling within this exchanger 6.

  The recirculated gas cooling device furthermore comprises means for additional cooling of the engine 1. These additional cooling means of the engine 1 thus enable the cooling device for the recirculated gases to cool not only the recirculated gases but also, when necessary. , the engine 1.

  These additional engine cooling means in fact allow the recirculated gas cooling device to be coupled to the engine cooling device so as to combine their action with a view to cooling the engine 1.

  Thus, there is provided a first fluid connection means 9 between the recirculated gas cooling device and the engine cooling device. This first fluidic connection means 9 makes it possible to connect the cooling device for the recirculated gases with the engine cooling device via, for example, two 3-way connections interposed respectively at the outlet of the pump means 8 of the cooling device. recirculated gases and at the inlet of the pump means 3 of the engine cooling device.

  The additional cooling means of the engine further comprises a first control valve 10 and a second control valve 11. These first and second control valves 10 and 11 will for example be 3-way control valves.

  The first control valve 10 comprises an input and two outputs. The inlet of this control valve 10 is connected to the output of the engine 1. The two outputs of this control valve 10 are connected respectively to the inlet of the control valve 5 of the engine cooling device and at an inlet of the second control valve 11 additional cooling means of the engine. It should be noted that in FIGS. 1a to 1c, the control valves 5 and 10 have been shown quite far from the engine 1, but these control valves 5 and 10 are in fact preferably integrated within the output housing of FIG. engine water 1.

  The first regulating valve 10 is thus a 3-way valve which makes it possible to regulate the cooling fluid coming from the engine 1 and to distribute it towards the control valve 5 of the engine cooling device and / or to the second control valve 11 additional cooling means of the engine. The first control valve 10 may for example be a thermostatic valve; we can take a thermostatic valve that starts to let the cooling fluid from the motor 1 to the second control valve 11 from 95 C.

  The second control valve 11 comprises two inputs and one output. The output of this second control valve 11 is connected to an inlet of the low-temperature cooling radiator 7. The two inputs of the second control valve 11 are connected respectively to an output of the pump means 8 of the cooling device. recirculated gases and at one of the outputs of the first control valve 10 additional cooling means of the engine.

  The second regulating valve 11 is thus a 3-way valve which makes it possible to regulate the flow of cooling fluids coming respectively from the electric water pump 8 of the recirculated gas cooling device and the first regulation valve 10, to direct these controlled cooling fluids to an inlet of the low temperature cooling radiator 7. The second control valve 11 may for example be a thermostatic valve; we can take a thermostatic valve that starts to move from 96 C, that is to say it begins to close the access to the cooling fluid from the electric water pump 8 from 96 vs.

  The first and second control valves 10 and 11 may for example be wax bulb thermostats as illustrated in Figures 2a-2b and Figures 3a-3b.

  Figures 2a-2b illustrate the operation of the wax bulb thermostat 10. In Fig. 2a, the temperature of the engine coolant (FRM) flowing through the bulb bulb thermostat 10 is less than the opening temperature. of the thermostat. Thus, the cooling fluid (FRM) from the engine 1 passes through the bulb bulb thermostat 10 and is directed only towards the control valve 5 of the engine cooling device.

  Once the coolant temperature (FRM) passing through the bulb bulb thermostat 10 is greater than the opening temperature of that thermostat, then the bulb bulb thermostat 10 is actuated, i.e. it opens the passage towards the second control means 11 of the additional cooling means of the engine. In this case, the cooling fluid (FRM) from the engine 1 is directed by the thermostat 10 both towards the control valve 5 of the engine cooling device, and towards the second control valve 11 additional cooling means of the engine.

  FIGS. 3a-3b illustrate the operation of the bulb bulb thermostat 11. In FIG. 3a, the temperature of the recirculated gas cooling fluid (FREGR) passing through the bulb bulb thermostat 11 is lower than the temperature of the closing this thermostat. Thus, the recirculated gas cooling fluid (FREGR) is not blocked and can be transmitted to the inlet of the low temperature cooling radiator 7.

  As soon as the thermostat 11 is in contact with a fluid having a temperature greater than or equal to the closing temperature of the bulb thermostat of wax 11, then it closes and prevents the cooling fluid of the recirculated gases (FREGR) from pass and be transmitted to the inlet of the low temperature cooling radiator 7. On the other hand, the cooling fluid from the engine via the control valve 10 will be transmitted to the inlet of the low temperature cooling radiator 7.

  In order not to have a flow stop within the exchanger 6, it is preferable for the thermostatic control valves 10 and 11 to operate according to the opening and closing curves of FIG. 4.

  When the temperature of the cooling fluids increases, the thermostatic control valve 10 will open when the engine coolant (FRM) has reached a first temperature (for example 95 C), and the second thermostatic control valve 11 will close in contact with a fluid having a second temperature, this second temperature being higher than the first temperature (by

example 96 C).

  When the temperature of the cooling fluids decreases, the thermostatic control valve 11 must be the first to move towards its rest position, that is to say its open position. Thus, the thermostatic control valve 11 may for example move to its rest position when the temperature of the cooling fluid reaches 92 C, while the thermostatic control valve 10 will move to its rest position, that is to say say its closed position, when the temperature of the cooling fluid reaches, for example, 91 C.

  A temperature sensor 13 may further be provided at the output of the engine 1.

  The engine 1 may also include a heat exchange means 12 between the engine coolant (FRM) and an air circuit for pulsing air in the passenger compartment of the vehicle. This heat exchange means 12, which is for example a heater, is connected on the one hand to the output of the engine 1 and on the other hand to the inlet of the pump means 3 of the engine cooling device. Thus, the engine coolant (FRM) can circulate not only in the engine cooling device but also circulates through this heat exchange means 12. Thus, when the cooling fluid flows through the heater 12, a heat exchange between this fluid and the air flowing through the air circuit is achieved. It is therefore possible to heat the air to be pulsed in the passenger compartment of the vehicle with the cooling fluid from the engine 1.

  Figures la to lc also illustrate schematically the operation of the cooling system during the main operating cycles of the engine 1.

  Figure la corresponds to the cold start phase of the engine 1. In this operating phase, the control means 10 prevents the passage of the engine coolant (FRM) to the control valve 11. The control valve 11 for its part, it passes the cooling fluid recirculated gas (FREGR) from the electric water pump 8 to the inlet of the low temperature cooling radiator 7. Finally, the control valve 5 of the engine cooling device closes the passage, and thus prevents the engine coolant (FRM) from reaching the inlet of the cooling radiator 2, as well as the degassing means 4.

  In this case, the engine cooling fluid (FRM) can circulate only through the heater 12 to heat the air to be pulsed inside the passenger compartment of the vehicle. In this configuration, the recirculated gas cooling device acts only on the exchanger 6 for cooling the recirculated gases.

  As the temperature of the engine coolant (FRM) increases, the control valve 10 always closes the access towards the control valve 11 and thus allows only a passage of the cooling fluid of the engine ( FRM) to the input of the regulating means 5 of the engine cooling device. In the same way, the control valve 11 always leaves the recirculated gas cooling fluid (FREGR) coming from the electric water pump 8 to reach the inlet of the low temperature cooling radiator 7. However, the control valve 5 of the engine cooling device allows the passage of the engine cooling fluid (FRM) to the cooling radiator 2 and to the degassing means 4, as shown in Figure 1b.

  This operating solution is the solution most often encountered in steady state for conventional lightly loaded launches. According to this operating mode, the recirculated gas cooling device makes it possible to cool the recirculated gases to a low temperature. The engine 1 is cooled by the cooling device of the engine and in particular the cooling fluid of the engine (FRM) which passes through it and which was cooled by the cooling radiator 2. The heat exchange process with the circuit air to be pulsed in the cockpit is still active. According to this configuration, the recirculated gas cooling device serves only to cool the recirculated gases and not to that of the engine 1.

  Finally, when the engine cooling fluid (FRM) in particular reaches higher temperatures, for example when the engine 1 is used at high speed (for speeds greater than 130km / h for example) then the recirculated gas cooling device completes the action of the engine cooling device to cool the engine 1. Indeed, when the engine coolant temperature (FRM) exceeds the opening temperature of the control valve 10 it allows the passage cooling fluid from the engine 1 to the control valve 11 (see Figure 2b). This engine cooling fluid (FRM) thus reaches the control valve 11 at a temperature such that the control valve 11 closes the passage of the recirculated gas cooling fluid (FREGR) from the electric water pump 8 towards the low temperature cooling radiator 7 (see Figure 3b). The control valve of the engine cooling device always allows a passage of the cooling fluid towards the cooling radiator 2 and the degassing means 4.

  Thus, as illustrated in FIG. 1c, the recirculated gas cooling device participates not only in the cooling of the recirculated gases but also in the cooling of the engine, in addition to the engine cooling device. Indeed, the recirculated gas cooling fluid (FREGR) being blocked by the control valve 11, it circulates in the engine cooling device via the fluidic connection means 9. The engine 1 is cooled both by the engine coolant (FRM) and recirculated gas coolant (FREGR).

  In addition, when the engine 1 operates at high speeds (for example beyond 130km / h), the power dissipated by the exchanger 6 to cool the recirculated gas is almost zero. As a result, the recirculated gas cooling device fully participates in the cooling of the engine 1.

  According to a second embodiment of the invention, the heat exchange means intended for cooling the recirculated gases is a heat exchanger 14 with two cooling levels (see FIGS. 6 to 8), that is to say that it comprises, in addition to the inlet and the outlet for circulating the recirculated gases, two inlets and two outlets intended for the circulation of fluids for example.

  This exchanger 14 with two cooling levels uses the engine coolant (FRM) at the output of the engine 1 to cool the recirculated gases at high temperature but also the recirculated gas cooling fluid (FREGR) at the outlet of the low cooling radiator temperature 7 of the recirculated gas cooling device, in order to super-cool the recirculated gases. The advantage of this exchanger 14 at two cooling levels is not having to cool all the recirculated gases with the recirculated gas cooling fluid (FREGR) at low temperature.

  In addition, the exchanger 14 at two temperature levels makes it possible to benefit from the power dissipated by the high temperature part, that is to say the part of the exchanger in which the engine cooling fluid (FRM) circulates, for improve cabin warming and engine warm-up 1.

  Figure 8 shows schematically the manner in which the two-level cooling exchanger 14 is integrated in the engine cooling system 1 according to the invention.

  With this exchanger 14 with two cooling levels, the recirculated gases first pass through the high temperature part through which the engine coolant (FRM) flows. Thus, the recirculated gases, which generally have a temperature of about 400 ° C. to 500 ° C., are cooled by this first part of the exchanger 14 with an engine cooling fluid (FRM) typically having a temperature of the order of 90 C.

  The second part of the exchanger 14, said low temperature part, is crossed by the recirculated gas cooling fluid (FREGR) which has a temperature below 60 C and which therefore allows a supercooling of the recirculated gases. This low temperature portion is separated from the high temperature portion by a fluid separation means 20, allowing the passage of recirculated gases.

  Figure 7 shows the principle of operation of the exchanger 14 at two levels of cooling. In this graph, the abscissa axis represents the distribution of the two parts of the exchanger 14 while the ordinate axis represents the temperature of the recirculated gases. It emerges from this diagram that a part of the recirculated gases is cooled at high temperature (x%) and a second part ((1-x)%) is cooled at low temperature.

  This type of exchanger 14 with two levels of cooling can also be achieved by putting in series two exchangers of gas / fluid type.

  According to a third embodiment of the invention, as illustrated in FIG. 9, a temperature sensor 15 is provided in order to more effectively drive the electric water pump 8 of the recirculated gas cooling device.

  This temperature sensor may for example be placed at the inlet of the low-temperature cooling radiator 7.

  When the temperature of the coolant at the outlet of the engine 1 is very high, and the hydraulic pressure supplied by the mechanical water pump 3 of the engine cooling device is sufficient to obtain the flow respecting the hydraulic specifications at the level of the engine. the exchanger 6, it is not useful to use the electric water pump 8.

  Thus, this temperature sensor 15 makes it possible not to operate the electric water pump 8 for this type of rolling, that is to say when the temperature of the engine cooling fluid (FRM) is very high, and thus to increase the life of the electric water pump 8, and reduce the power consumption of the vehicle.

  According to a fourth embodiment of the invention, as illustrated in FIG. 10, the control valve 10 of the additional cooling means of the motor is replaced by a simple three-way connection.

  The thermostatic control valve 11 is in turn replaced by an electric regulating valve 16. This electric regulating valve 16 is controlled by a temperature sensor 15 placed at the inlet of the low-temperature cooling radiator 7.

  The use of a single electric control valve 16 in place of the two thermostatic control valves allows more flexibility in controlling the temperature according to the speed and the load of the engine 1.

  Thus, during a cold start, for example, the electric regulation valve 16 allows a circulation of the recirculated gas cooling fluid (FREGR) in the recirculated gas cooling device, but this electric regulation valve 16 also allows have a low flow rate of the recirculated gas cooling fluid (FREGR) through the fluid connection means 9 to the engine cooling device, to create a circulation of the recirculated gas cooling fluid (FREGR) to the engine 1 and the heater 12 to improve the temperature rise of both the engine 1 but also the heating of the passenger compartment.

  According to a fifth embodiment of the invention, as illustrated in FIG. 11a, there is provided, in addition to the electric regulating valve 16, another regulating valve 17, this other regulating valve 17 being able to be example an electric control valve.

  This electric control valve 17 is a three-way valve which comprises two inputs and an output, the output being connected to the input of the heater 12, the first input being connected to the output of the motor 1, and the second input being connected to the outlet of the electric water pump 8 of the recirculated gas cooling device. In addition, two fluidic connection means 18 and 19 are provided.

  The first fluid connection means 18 connects the output of the heater 12 to the inlet of the heat exchanger 6. Thus, the loop composed of the electric control valve 17, the heater 12, the fluid connection means 18 , the exchanger 6 and the electric water pump 8 acts as an additional heating system implanted within the recirculated gas cooling device.

  Indeed, for example at the cold start as illustrated in FIG. 11 b, the electric regulation valve 17 closes the access to the cooling fluid (FRM) coming from the engine 1 and the electric regulation valve 16 also closes the passage of the cooling fluid (FRM) from the engine 1. Thus, if a request for heating to the passenger compartment is made, the recirculated gas cooling fluid (FREGR) flowing through the exchanger 6 flows through the unit heater 12 via the electric control valve 17. It can be envisaged that the electric control valve 16 is open on the outlet side of the electric water pump 8, even if there is a demand for heating the passenger compartment, for even better cool the recirculated gases.

  The fluidic connection means 19 makes it possible for it to connect the output of the engine 1 to the inlet of the mechanical water pump 3. This fluidic connection means 19 serves to circulate the engine cooling fluid (FRM) during the rise in temperature, since this engine cooling fluid (FRM) can no longer circulate via the heater 12 because of the closing of the electric control valve 17.

  The electric control valve 16 and the electric water pump 8 can be controlled more efficiently thanks to the temperature sensor 15 placed at the inlet of the means of the low-temperature cooling radiator 7. The electric water pump 8 will operate in particular according to the positioning of the electric control valve 16, but also according to the heating demand of the passenger compartment.

  According to a sixth embodiment of the invention, as illustrated in FIG. 12a, the control valve 5 of the engine cooling device is replaced by a three-way control valve 20 which comprises an additional output with respect to the control valve 5 described above. This outlet is connected to the inlet of the regulation valve 11 of the recirculated gas cooling device by a fluidic connection means 21. The control valve 11 of the additional cooling means of the engine may for example be an electric control valve 16 as described above.

  This embodiment is similar to the embodiment shown in FIG. 10, with the difference that, during the cold start of the engine 1 in particular, the recirculated gas cooling fluid (FREGR) is cooled not only by the radiator low temperature cooling of the recirculated gas cooling device but also by the cooling radiator 2 of the engine cooling device. This operating mode allowing cooling of the recirculated gases more efficient at cold start of the engine 1 is presented in FIG. 12b.

  The reader will understand that many changes can be made without materially escaping the new lessons and benefits described here. Therefore, all modifications of this type are intended to be incorporated within the range of the vehicle engine and the control method of a vehicle engine according to the invention.

Claims (34)

  A vehicle engine comprising an engine cooling device (1) and a gas cooling device (EGR) separate from the engine cooling device (1), the engine (1) being characterized in that the cooling device gas (EGR) comprises additional cooling means of the engine (1).   2. Engine according to claim 1, characterized in that the gas cooling device (EGR) comprises a heat exchange means (7) for cooling a gas cooling fluid (FREGR), a heat exchange means ( 6) between the gases (EGR) and the gas coolant (FREGR), and a pump means (8) for circulating the gas coolant (FREGR) in the gas cooling device (EGR).   3. Engine according to claim 2, characterized in that the heat exchange means (6) between the gas (EGR) and the gas cooling fluid (FREGR), the heat exchange means (7) for cooling the gas coolant (FREGR) and the pump means (8) are connected in series by fluid connection means to form a gas coolant circulation loop (FREGR).   4. Engine according to any one of claims 1 to 3, characterized in that the engine cooling device (1) comprises a heat exchange means (2) for cooling an engine cooling fluid (FRM) and a pump means (3) for circulating the engine coolant (FRM) in the engine cooling device (1), the heat exchange means (2) for cooling the engine coolant (FRM) and the pump means (3) being connected in series by fluid connection means.   5. Engine according to claim 4, characterized in that the engine cooling device (1) further comprises a control valve (5) adapted to regulate a flow of the engine cooling fluid (FRM) between an engine output (1) and the heat exchange means (2) for cooling the engine coolant (FRM).   6. Engine according to claim 5, characterized in that the control valve (5) is a thermostatic valve.   7. Motor according to any one of claims 5 or 6, characterized in that the additional cooling means of the motor (1) comprises a first fluid connection means (9) between the engine cooling device (1) and the gas cooling device (EGR), a first control valve (10) for the engine coolant (FRM), the first control valve (10) being a three-way valve interposed in the engine cooling device (1). ), a second control valve (11) of the gas coolant (FREGR), the second control valve (11) being a three-way valve interposed in the gas cooling device (EGR), the first and second valves regulating means being further connected to each other by a second fluid connection means.   8. Motor according to claim 7, characterized in that the first fluid connection means (9) connects an outlet of the pump means (8) of the gas cooling device (EGR) to an inlet of the pump means (3). of the engine cooling device (1).   9. Motor according to any one of claims 7 or 8, characterized in that the first control valve (10) of the additional cooling means of the motor (1) comprises an input and two outputs, the input being connected to the the output of the motor (1), and the two outputs respectively connected to an input of the control valve (10) of the engine cooling device (1) and to an input of the second control valve (11). additional cooling of the engine (1).   10. Engine according to claim 9, characterized in that the second control valve (11) of the additional cooling means of the engine (1) comprises an output and two inputs, the output being connected to an input of the exchange means. thermal device (7) for cooling the gas cooling fluid (FREGR), the inlets being respectively connected to an outlet of the pump means (8) of the gas cooling device (EGR) and to one of the outlets of the first control valve 5 (10) of the additional cooling means of the motor (1).   11. Motor according to any one of claims 9 to 10, characterized in that the first and second control valves of the additional cooling means of the motor (1) are thermostatic valves.   12. Motor according to claim 11, characterized in that the control valve (5) of the cooling device of the rnoteur (1) is adapted to allow a passage of the engine cooling fluid (FRM), the output of the first control valve (10) of the additional cooling means of the motor (1) to the inlet of the heat exchange means (2) for cooling the engine cooling fluid (FRM), from a first temperature, the first control valve (10) of the additional cooling means of the motor (1) is able to allow a passage from the output of the motor (1) to the inlet of the second control valve (11) of the additional cooling means of the engine (1), from a second temperature, and the second control valve (11) of the additional cooling means of the engine (1) is able to allow passage of the output of the first control valve ( 10) means s additional cooling of the engine (1) to the inlet of the heat exchange means (7) for cooling the gas cooling fluid (FREGR), from a third temperature.   13. Engine according to claim 12, characterized in that the first, second and third temperatures are respectively 89 C, 95 C and 96 C.   14. Motor according to claim 10, characterized in that the second control valve (11) of the additional cooling means of the motor (1) is an electric valve.   15. Motor according to claim 14, characterized in that the gas cooling device (EGR) comprises a temperature measuring means (15) for measuring a temperature at the outlet of the second control valve (11) means additional cooling of the engine (1), the second control valve (11) of the additional cooling means of the engine (1) being controlled according to the temperature measured by the temperature measuring means (15).   16. Motor according to any one of claims 14 or 15, characterized in that the control valve (5) of the engine cooling device (1) is a three-way valve comprising an output connected to the second connecting fluidic connecting means. the output of the first control valve (10) at the inlet of the second control valve (11).   17. Engine according to any one of claims 2 to 16, characterized in that the heat exchange means (7) for cooling the gas cooling fluid (FREGR) is a cooling radiator.   18. Motor according to any one of claims 2 to 17, characterized in that the pump means (8) of the gas cooling device (EGR) is an electric water pump.   19. Motor according to any one of claims 3 to 18, characterized in that the heat exchange means (2) for cooling the engine cooling fluid (FRM) is a cooling radiator.   20. Motor according to any one of claims 3 to 19, characterized in that the pump means (3) of the engine cooling device (1) is a mechanical water pump.   21. Motor according to any one of claims 3 to 19, characterized in that the pump means (3) of the engine cooling device (1) is an electric water pump.   22. Motor according to any one of claims 3 to 21, characterized in that the cooling device of the engine (1) further comprises a degassing means (4) connected in shunt of the heat exchange means (2) for cool the engine coolant (FRM).   23. Motor according to any one of claims 2 to 22, characterized in that the heat exchange means (6) between the gases (EGR) and a cooling fluid comprises an inlet and an outlet for gases (EGR). , and a fluidic inlet and outlet, the fluidic inlet being connected to the outlet of the heat exchange means (7) for cooling the gas cooling fluid (FREGR) and the fluidic outlet being connected to the inlet of the means pump (8) of the gas cooling device (EGR).   24. Motor according to claim 23, characterized in that the heat exchange means (14) between the gases (EGR) and the cooling fluid further comprises a fluidic inlet and outlet for the engine cooling fluid (FRM). ).   25. Motor according to claim 24, characterized in that the inlet for the engine cooling fluid (FRM) is connected to the output of the engine (1) and the output for the engine coolant (FRM) is connected. at the inlet of the pump means (3) of the engine cooling device (1).   26. Motor according to any one of the preceding claims, characterized in that it comprises a heat exchange means (12) between the engine cooling fluid (FRM) and air intended to be pulsed in a passenger compartment. of the vehicle, the heat exchange means (12) being connected on the one hand to the output of the engine (1) and on the other hand to the inlet of the pump means (3) of the engine cooling device (1). ).   27. Motor according to claim 26, characterized in that it further comprises a cooling fluid control valve (17) and a first and a second fluid connection means, the control valve (17) being interposed between the motor output (1) and an input of the heat exchange means (12) between the engine coolant (FRM) and the air circuit and further comprising an input connected to the output of the pump means (8). ) of the gas cooling device (EGR), the first fluid connection means (18) connecting an output of the heat exchange means (12) between the engine cooling fluid (FRM) and the air circuit and a input of the heat exchange means (6) between the gases (EGR) and the gas cooling fluid (FREGR), and the second fluid connection means (19) connecting the output of the engine (1) to the inlet of the pump means (3) of the engine cooling device (1) - 28. A method of controlling a vehicle engine, comprising a recirculated gas circuit (EGR), characterized in that the engine (1) is cooled by a cooling device of the engine (1) and the gases are cooled. (EGR) by a gas cooling device (EGR) separate from the engine cooling device (1), and the engine (1) is also cooled by the recirculated gas cooling device (EGR).   29. The method of claim 28, characterized in that one controls the cooling device of the motor (1) according to a temperature at an output of the engine (1).   30. The method according to claim 29, characterized in that, beyond a first threshold value of the temperature at the output of the engine (1), a cooling fluid (FRM) of the engine cooling device is cooled ( 1).   31. A method according to any one of claims 28 to 30, characterized in that the recirculated gas cooling device (EGR) is controlled as a function of a temperature at an output of the engine (1) and a temperature at an outlet of a heat exchange means (6) of the gas cooling device (EGR) between the gases (EGR) and a gas cooling fluid (FREGR).   32. The method according to claim 31, characterized in that, beyond a second threshold value of the temperature at the output of the engine (1), the cooling fluid of the gases (FREGR) is directed towards the engine (1). ).   33. The method of claim 32, characterized in that the second threshold value of the temperature at the output of the motor (1) is greater than the first threshold value of the temperature at the output of the motor (1).   34. Process according to any one of claims 31 to 33, characterized in that, below the first threshold value of the temperature at the outlet of the engine (1), the cooling fluid of the gases (FREGR) is directed towards heat exchange means (12) for heating air to be pulsed in a passenger compartment of the vehicle.