FR3048028A1 - THERMAL MANAGEMENT DEVICE OF A SUPERCAUTION AIR COOLER. - Google Patents

Abstract

The invention relates to a device for thermal management of a charge air cooler comprising an air charge air cooler (5) placed upstream of an internal combustion engine (1), said air cooler comprising a charge air inlet (57) from a turbocharger (3, 7), a charge air outlet (58) to the engine air intake, and a heat exchange bundle ( 51) consisting of a plurality of heat exchange surfaces (52) between a cooling air flowing through said heat exchange surfaces and the supercharging air distributed between said heat exchange surfaces. According to the invention, there are provided means for determining the temperature (T1) of the cooling air passing through said air cooler (5), a heating device (13) for said heat exchange surfaces and means for activation of said heater (13) when the temperature (T1) of the cooling air is below a predetermined temperature threshold.

Description

Thermal management device of a charge air cooler

The present invention relates to the field of turbocharged heat engines, in particular for motor vehicles. It relates more particularly to a thermal management device of a charge air cooler.

In the automotive field of internal combustion engines, it is known to use an exhaust gas recirculation circuit, called "EGR" circuit, for "Exhaust Gas Recirculation", according to English terminology, which allows to reintroduce a part of the exhaust gases to the intake of the engine. This system comprises for example a controlled valve to control the recirculation of gases in the circuit and means for cooling all or part of the recirculated gases before their readmission to the engine. The intake of exhaust gas at the intake of the engine makes it possible to significantly reduce nitrogen oxide emissions.

To improve the power of the engine, it is also brought to introduce air underpressure at the engine. For this, at least one turbocharger is used which supplies pressurized air, which is sent to the engine intake. It is then necessary to cool the charge air, from the turbocharger, by means of a charge air cooler, also commonly referred to as "RAS", arranged upstream of the engine in the charge air intake circuit. . Indeed, the air from the turbocharger is at a high temperature and it is necessary to cool before sending it to the engine inlet, so that the latter can operate in optimal conditions. The RAS, placed at the output of the turbocharger, thus reduces the temperature of the charge air at the outlet of the turbocharger, which allows in particular to improve the density of the air for the benefit of the combustion efficiency. The SARs are generally air / air or air / liquid type heat exchangers, which have a high cooling capacity (very low wall temperature).

In the case of a low-pressure exhaust gas recirculation circuit, the mixture of the recirculated exhaust gas with the fresh intake air is upstream of the charge air cooler. This gas mixture, consisting of air and a greater or lesser proportion of recirculated exhaust gas, is relatively rich in water due to the combustion of the fuel. In contact with the walls of the charge air cooler, this gas mixture generates a condensation of water. However, under certain conditions, in particular when the temperature of the cooling air passing through the cooler is too low and in particular below a temperature threshold at which the water resulting from the condensation is transformed into frost, the resulting water accumulated condensation in the charge air cooler can go as far as blocking the air passage section and thus block all or part of the engine air supply circuit, or else is likely to cause mechanical stresses that can lead to a deterioration of the operation of the charge air cooler (leakage, degradation of the rigidity, breaking of the points of attachment).

From patent document US2014083398 there is known a system for the mechanical purging of the condensed water accumulated in the charge air cooler, which is triggered according to the temperatures and pressures measured in the intake manifold. However, this system is not entirely satisfactory because it assumes that a volume of water stagnates permanently at the low point of the charge air cooler, with risks of aspiration by the engine or corrosion .

It is therefore desirable to avoid or at least limit as much as possible this phenomenon of condensation and freezing of the water present in the gaseous mixture consisting of air and recirculated exhaust gas, in the air cooler of overeating. For this purpose, the invention relates to a thermal management device of a charge air cooler comprising an air charge air cooler intended to be placed upstream of an internal combustion engine, said air cooler comprising a charge air inlet from at least one turbocharger, a charge air outlet to the engine air intake, and a heat exchange bundle comprised of a plurality of engine air surfaces; thermal exchange between a cooling air circulating through said heat exchange surfaces and the supercharging air distributed between said heat exchange surfaces, characterized in that it comprises means for determining the air temperature of cooling through said air cooler, a heater for at least a portion of said heat exchange surfaces and means for activation of said heater when the temperature of the cooling air is below a predetermined temperature threshold.

Advantageously, said heating device comprises a heat exchanger provided with a heat exchange bundle thermally coupled to at least a portion of said heat exchange surfaces of said air cooler, downstream of said air cooler with respect to the circulation. cooling air.

Advantageously, said heat exchanger is coupled to a supply circuit for supplying said heat exchanger with a heated heat transfer fluid to supply calories transported by said heated heat transfer fluid to said heat exchange bundle of said heat exchanger.

According to one embodiment, said supply circuit is connected to the engine cooling circuit so that said heated heat transfer fluid is supplied by the coolant circulating in the engine cooling circuit at the motor output.

According to another embodiment, said supply circuit comprises an independent heat transfer fluid circulating circuit, said circulation circuit being provided with a heating means for heating the coolant flowing in it.

Preferably, said heating means consists of an electrical resistance integrated in said coolant circulation circuit.

Advantageously, said supply circuit comprises means for regulating the flow of the heated heat transfer fluid circulating in said supply circuit.

Preferably, said regulating means comprise a proportional valve.

Preferably, the charge air at the inlet of said air cooler comprises recirculated exhaust gases from the engine. The invention also relates to a motor vehicle comprising a thermal management device according to the invention. Other features and advantages of the invention will appear on reading the following description of a particular embodiment of the invention, given by way of indication but not limitation, with reference to the appended figures in which: FIG. 1 shows a general schematic representation of an internal combustion engine assembly with a charge air intake circuit, incorporating a thermal management device of the charge air cooler according to the invention; - Figure 2 is a schematic sectional view of the charge air cooler illustrated in Figure 1; FIG. 3 is a diagrammatic representation from above of the charge air cooler associated with a heating device as illustrated in FIG. 1; - Figure 4 is a schematic representation of the heater of the charge air cooler of Figure 1 according to a first embodiment; FIG. 5 is a diagrammatic representation of the heating device of the charge air cooler of FIG. 1 according to a second embodiment; FIG. 6 is a block diagram illustrating an exemplary regulation of the operation of the air cooler heater. The invention is described in the context of an internal combustion engine assembly comprising an internal combustion engine 1 and a charge air intake circuit 2 having a supercharging air compressor. The charge air intake circuit comprises an air duct 4 connecting the compressor 3 to the engine 1 and a charge air cooler 5 mounted on the air duct 4 between said compressor 3 and the engine 1 for the engine. cooling the charge air sent to the engine 1. Thus, the supercharging air, heated after compression, can be cooled through the charge air cooler 5 before being injected at the engine 1. The engine assembly further comprises an exhaust circuit comprising a compressor driving turbine 7 and an exhaust gas recirculation circuit 8 connected to the exhaust circuit downstream of the turbine 7 and to the exhaust circuit. intake 2 upstream of the compressor 3. Also, the gaseous mixture at the inlet of the charge air cooler 5 consists of intake air coming from the outside and a greater or lesser proportion of ga z recirculated exhaust. The exhaust gas recirculation circuit 8 may comprise a cooling circuit 9 of the recirculated exhaust gas.

A temperature sensor is preferably disposed at the inlet of the air intake circuit so as to be able to determine the temperature T1 of the air coming from the outside entering the air intake circuit. The temperature sensor can also be arranged at the exterior mirror to measure the outside air temperature or be coupled to another outdoor air temperature sensor on the vehicle. The engine assembly also comprises a cooling circuit 10 of the engine 1 for circulating a coolant, for example a coolant comprising glycol, through the engine 1 to remove the heat generated by the operation of the engine. The cooling circuit 10 comprises a heat transfer fluid inlet 11 for injecting the heat transfer fluid into the cooling circuit 10 and an outlet 12 for discharging the coolant heated by the engine.

The charge air cooler 5 implanted in the charge air intake circuit is an air / air type heat exchanger. As shown in FIG. 2, the air charge air cooler comprises a housing 50 in which a heat exchange beam 51 is disposed comprising a plurality of heat exchange surfaces 52 delimiting between them circuits 53, 54 alternate for the supercharging air to be cooled and for the cooling air. The heat exchange surfaces 52 may for example be flat tubes in which circulates the cooling air and between which the charge air passes. The housing includes a first side wall 55, located on the left in Fig. 1, forming a header plate through which cooling air from outside is fed into the tubes of the air cooler bundle. It further comprises a second side wall 56, located on the right in Figure 1, constituting the rear face of the beam as opposed to the front face through which the cooling air enters the heat exchange beam.

The air charge air cooler 5 has a charge air inlet 57 through which the charge air from the compressor 3 arrives, to be distributed between the heat exchange surfaces 52 between said supercharging air and cooling air. The air cooler 5 also has a charge air outlet 58 which discharges the cooled supercharging air from the heat exchange surfaces 52 to the engine 1.

In accordance with the invention, and as illustrated with reference to FIGS. 1 and 3, the air charge air cooler 5 is thermally coupled to a heater 13, designed to heat the air cooler 5 when the temperature T1 of the cooling air passing through the cooler 5 is below a temperature threshold at which the water present in the gaseous mixture constituting the supercharging air to be cooled is liable to condense in the cooler and where this water resulting from condensation risks to turn into frost. This temperature threshold is for example set at 10 ° C. Indeed, by heating the air supercharger air cooler, we obtain a lower temperature gradient between it and the gaseous mixture constituting the supercharging air therethrough and therefore a cooling of this gas mixture less important within the air cooler. In this way, the condensation in the air cooler of the water present in the gaseous mixture constituting the supercharging air to be cooled is limited or even eliminated.

The heating device is advantageously constituted by a heat exchanger 13 allowing a transfer of heat from a heated heat transfer fluid therethrough to the air supercharging cooler 5. Said heat exchanger 13 more precisely comprises a heat exchange bundle 130 thermally coupled to at least a portion of the heat exchange bundle 51 of the air supercharging air cooler 5, at the rear face 56 thereof and therefore downstream of the latter with respect to the circulation cooling air, so as not to degrade the heat exchange between the cooling air and the charge air. The bundle of the heat exchanger 13 constituting the heater of the air cooler is of substantially identical design to that of the air cooler, in terms of sizing the tubes and the spaces between the tubes. The heat exchanger 13 preferably covers only a part of the rear face 56 of the heat exchange bundle of the air cooler 5 and, in particular, the lower part of the rear face of this bundle, which constitutes in fact the zone the cooler 5 where the temperature gradient between it and the gaseous mixture constituting the supercharging air passing therethrough is the most important, insofar as the charge air inlet 57 in the air cooler 5 is arranged in the lower part of it. The heat exchanger 13 comprises a fluid inlet 14 for supplying the heat exchanger 13 with heated heat transfer fluid, so that the heat exchange bundle of the heat exchanger 13 can recover a portion of the calories transported. by the heated heat transfer fluid received at the input for transmission to the air cooler 5, and a fluid outlet 15 through which the heated heat transfer fluid is removed from the heat exchanger 13 after giving up part of its calories. The inlet 14 and the fluid outlet 15 of the heat exchanger 13 are connected to a supply circuit for supplying said heat exchanger 11 with the heated heat transfer fluid to supply the calories present in the heat transfer fluid heated to the beam heat exchanger of the heat exchanger 13.

According to a first embodiment described with reference to FIG. 4, the heated heat transfer fluid supply circuit of the heat exchanger 13 is coupled to the cooling circuit 10 of the engine 1. More precisely, the fluid outlet 15 of the the heat exchanger 13 is connected to the inlet 11 of the cooling circuit and the outlet 12 of the cooling circuit is connected to the fluid inlet 14 of the heat exchanger 13 via a proportional valve 16, for controlling the flow of fluid in the supply circuit. In this way, the heat exchanger 13 can be fed by the coolant at the output of the engine.

Thus, when a risk of condensation and / or freezing in the air cooler is detected, in other words that it is detected that the measured temperature T1 is below the predetermined temperature threshold, for example 10 ° C., the heating is activated. The valve 16 is then controlled to allow the heat exchanger 13 to be fed with the coolant coming from the engine (otherwise the valve 16 is closed). The heat exchanger 13 will then recover a portion of the calories present in the coolant for transmission to the air-cooler 5. As a result of this heat transfer, the air cooler 5 will rise in temperature. The higher the temperature of the coolant at the inlet of the heat exchanger 13, the more it will be able to transmit calories to the air cooler 5. Also, one way to optimize the efficiency of the system is to provide the engine coolant at the inlet of the heat exchanger 13 after passage of the coolant for example in the engine oil heater and / or in any other system for raising the coolant temperature.

In addition, the coupling with the engine cooling circuit makes it possible to improve the cooling of the engine occasionally when the heating device is activated. In fact, the calories present in the coolant at the outlet of the engine are dissipated through the passage in the heating device of the air cooler, which has the effect of lowering the temperature of the engine coolant at the inlet of the engine. cooling system.

According to another embodiment, with reference to FIG. 5, the heat exchanger heat exchanger supply circuit 13 comprises an independent heat transfer fluid circulation circuit 17, arranged between the inlet and the outlet of the heat exchanger. heat exchanger 13, and this circulation circuit 17 is provided with a pump 18 for circulating the fluid and a heating means 19, for example an electrical resistance integrated in the circuit, for heating the coolant flowing in that in order to supply a heated heat transfer fluid at the inlet 14 of the heat exchanger 13. The proportional valve 16, for controlling the flow rate of the fluid in the circuit, is disposed in the circuit between the electrical resistance 18 and the inlet 14 of the heat exchanger 13.

According to an alternative embodiment not shown, the heat transfer fluid may be the lubricating oil of the engine 1, so that the heat exchanger 13 is an oil cooler. In this case, the supply circuit of the heat exchanger 13 is connected to the engine lubrication circuit.

With reference to FIG. 6, a regulation of the operation of the heating device of the air cooler 5 can also be implemented, depending on the conditions of the temperature of the outside air or of the inlet air of the intake circuit. and charge air cooled at the outlet of the air cooler 5. A temperature sensor is disposed at the outlet of the air cooler 5 so as to be able to determine the temperature T2 of the charge air cooled at the outlet of the air cooler 5. Thus, the regulation firstly comprises measuring the temperature T1. If this temperature is greater than the predetermined temperature threshold, for example 10 ° C, referenced "a" in Figure 6, then the proportional valve 16 is closed. If the temperature T1 is below the predetermined critical threshold and / or the temperature T2 is less than a second temperature threshold, for example 10 ° C., referenced "b" in FIG. 6, then the valve 16 is opened. valve 16 is kept open as long as this condition is fulfilled. When this condition is no longer achieved, the valve 16 is closed.

In the case of the second embodiment described with reference to FIG. 5 with an independent heated heat transfer fluid circulation circuit, a temperature probe may be arranged at the outlet of the heat exchanger 13, so as to be able to determine the temperature T3 of the heat transfer fluid at the outlet of the heat exchanger 13. This measurement of the temperature T3 makes it possible to regulate the temperature of the heat transfer fluid at the outlet of the heat exchanger 13 by means of the electrical resistance 19 integrated in the circuit circulation 17 of the coolant. For example, the electrical resistance is controlled when the temperature T3 is less than or equal to 3 ° C.

Claims (10)

A device for thermal management of a charge air cooler comprising an air charge air cooler (5) to be placed upstream of an internal combustion engine (1), said air cooler ( 5) comprising a charge air inlet (57) from at least one turbocharger (3, 7), a charge air outlet (58) to the engine air intake, and a charge engine harness heat exchange (51) consisting of a plurality of heat exchange surfaces (52) between a cooling air flowing through said heat exchange surfaces and the supercharging air distributed between said heat exchange surfaces, characterized by comprising means for determining the temperature (T1) of the cooling air passing through said air cooler (5), a heater (13) of at least a portion of said exchange surfaces thermal e t activation means of said heater (13) when the temperature (T1) of the cooling air is below a predetermined temperature threshold. 2. Device according to claim 1, characterized in that said heating device comprises a heat exchanger (13) provided with a heat exchange bundle thermally coupled to at least a portion of said heat exchange surfaces of said cooler to air (5), downstream of said air cooler with respect to the circulation of the cooling air. 3. Device according to claim 2, characterized in that said heat exchanger (13) is coupled to a supply circuit (10, 17) for supplying said heat exchanger (13) with a heat transfer fluid heated to provide calories transported by said heated coolant to said heat exchange bundle of said heat exchanger. 4. Device according to claim 3, characterized in that said supply circuit is connected to the cooling circuit (10) of the engine so that said heated heat transfer fluid is supplied by the coolant circulating in the engine cooling circuit. at the motor output. 5. Device according to claim 3, characterized in that said supply circuit comprises an independent coolant circulation circuit (17), said circulation circuit (17) being provided with a heating means for heating the heat transfer fluid. circulating in this one. 6. Device according to claim 5, characterized in that said heating means comprises an electrical resistor (19) integrated in said coolant circulation circuit (17). 7. Device according to any one of claims 3 to 6, characterized in that said supply circuit comprises means for regulating the flow of heated heat transfer fluid circulating in said supply circuit. 8. Device according to claim 7, characterized in that said regulating means comprise a proportional valve (16). 9. Device according to any one of the preceding claims, characterized in that the supercharging air at the inlet of said air cooler comprises recirculated exhaust gas from the engine. 10. Motor vehicle characterized in that it comprises a thermal management device according to any one of the preceding claims.