FR3096404A1 - Device for regulating the temperature of at least one element of a supercharged heat engine - Google Patents

Abstract

The invention relates to a device (10) for thermal management of an engine (1), in particular of a combustion engine for a vehicle, comprising an engine cooling circuit (2) and an independent flow circuit (3 ) a heat transfer fluid circulating in a heat exchanger (4) through which a charge air intended to supply the heat engine with intake gas, this heat exchanger (4) being crossed by a heat transfer fluid, characterized in that ' it comprises a heating means (20) of the heat transfer fluid, the operation of which makes it possible to transmit calories to the heat exchanger (4), in particular when the engine is started and / or under the condition of icing temperature of the internal walls of the exchanger thermal. The invention also relates to a vehicle having such a device. Figure for the abstract: Fig. 1

Description

Description Title of the invention: Device for regulating the temperature of at least one element of a supercharged heat engine

The invention relates to the field of turbocharged heat engines or those of hybrid technology comprising a turbocharged heat engine.

[0002] More particularly, the invention relates to the regulation of the temperature of various elements of a heat engine or of various components supplied to this heat engine in order to optimize the operation of the latter.

This regulation mainly concerns, on the one hand, the temperature of the air sent to the engine intake and, on the other hand, the temperature of the water and the oil of the heat engine to obtain a rapid rise in temperature of these two elements shortly after starting this heat engine.

It is known to equip a heat engine, whether it is a gasoline engine or a diesel engine with a turbocharger for improving the performance of this engine.

[0005] We know that such a turbocharger, driven by the exhaust gases of the engine, produces fair under pressure, called charge air or intake air, which is sent to the engine intake.

This supercharging air is brought, due to its compression, to a high temperature and it should be cooled prior to its admission to the engine, so that the latter can operate under optimal conditions.

This is done by a charge air cooler, also called RAS for short, placed at the outlet of the turbocharger in order to lower the temperature of the charge air, which mainly allows the density of the engine to be increased. air supplied to the engine in order to increase its power.

The RAS cools the charge air by heat exchange between the compressed air and a coolant, such as water.

This cooling liquid circulates through a cooling circuit which passes through the heat engine so that the engine coolant is able to participate in the cooling and heating of the compressed air according to the temperature of the engine .

When the engine coolant becomes too hot, it no longer provides sufficient charge air cooling.

This takes place when the heat engine is hot and the coolant, although cooled by the radiator of the engine coolant circuit, has not been lowered to a temperature low enough to be able to cool this charge air.

As a temperature of the charge air that is too high can lead to an increase in pollutant emissions, for example 2 nitrogen oxides, more efficient cooling of the charge air than that carried out by the coolant should be considered. of the engine, when it is fully loaded.

[0007] With regard to another aspect of the thermal management of the charge air, a traditional thermal vehicle, and even more a vehicle equipped with hybrid technology, needs an efficient but rapid rise in temperature. coolant together with engine oil to reduce its consumption.

The rise in temperature of the cooling liquid and of the oil of a heat engine is ensured solely by the dissipation of the calories resulting from the combustion by conduction through the material of the cylinder head and the cylinder block.

When the temperature rises, the thermostat of the engine cooling circuit is closed and therefore the radiator on the front of this circuit does not cool the cooling liquid.

The coolant and the oil thus rise in temperature at the same time, more quickly.

This avoids, among other things, the emission of pollutants, such as carbonic acid and carbon monoxide, and fuel consumption is reduced.

[0008] In order to improve this rise in engine temperature, more or less complex thermal regulation processes can be envisaged without, however, being entirely satisfactory.

Very often, the charge air circuit is associated with an exhaust gas recirculation circuit so that a mixture of the recirculated exhaust gases with the fresh intake air takes place upstream of the exhaust cooler. charge air.

This hot 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 cold walls of the charge air cooler, this gas mixture generates water condensation.

However, under certain conditions, in particular when the temperature of the internal walls of the charge air cooler is too low, in particular below a temperature threshold above which the water resulting from the condensation turns into frost, the water resulting from the condensation can thus go so far as to block all or part of the motor supply circuit.

Another drawback observed is a situation causing significant mechanical stresses which can lead to a degradation of the operation of the charge air cooler, such as leaks, a degradation of the rigidity of the exchanger, or even a rupture of the attachment points. of the building blocks of the RAS.

Given the fact that the condensation phenomenon appears in the presence of a temperature gradient between the charge air and the internal walls of the RAS, the risk of frost and malfunction appears under cold weather conditions at start-up of the motor.

When the engine is started, there is significant condensation on the internal walls of the RAS cc which generates frost blocking the charge air inside the RAS, thereby preventing normal operation of the heat engine.

In addition, in the absence of icing, a large amount of water in the engine intake can cause a significant drop in engine performance, stop its operation, or even no starting.

[0010] Current heat engines have a high efficiency, which is advantageous in terms of fuel consumption but which extends their temperature rise time, so that these heat engines do not respond to the problem of RAS icing at start-up of the vehicle.

The problem at the basis of the present invention is therefore to regulate the temperature of the cooling liquid circulating through the RAS in order to bring the latter into optimal operating conditions, by reducing the phenomenon of internal icing of the RAS or evaporating the quantity of water contained in the RAS, in particular when the vehicle engine is started.

To this end, the invention relates to a thermal management device of an engine, in particular of a combustion engine for a vehicle, comprising an engine cooling circuit and an independent flow circuit. a heat transfer fluid circulating in a heat exchanger crossed by a charge air intended to supply the heat engine with intake gas, this heat exchanger being traversed by a heat transfer fluid.

11 is essentially characterized by the fact that it comprises a means for heating the heat transfer fluid, said heating means making it possible to transmit calories to the heat exchanger, in particular when the engine is started and / or under a temperature condition of icing of the internal walls of the heat exchanger.

The device of the invention can also include the following characteristics taken separately or in combination with each other: - the independent flow circuit of a heat transfer fluid comprises a main loop comprising a water pump, the heat exchanger between the charge air and the coolant, a thermostat, a cooler for the coolant, as well as a radiator bypass branch connected to the main loop by first and second junctions arranged respectively upstream of the thermostat and downstream of the cooler , according to a direction of flow of the heat transfer fluid in the flow circuit; - The heating means is arranged downstream of the heat exchanger so that the heat input is controlled by the elements of the independent heat transfer fluid flow circuit, in particular the thermostat and / or the cooler; - The heating means is arranged upstream of the heat exchanger so that the calorie input from the heating means is directly transmitted to the heat exchanger; - The heating means is implemented when the engine is started from cold; the device comprises a means for controlling said heating means integrating a storage memory in which is recorded at least one operating parameter of said heating means, in particular an operating time or a heating power of said heating means; - said control means of said heating means adjusts the duration of activation and / or the power of said heating means in a variable manner according to at least one operating parameter of the vehicle, in particular the ambient temperature and / or the temperature of the circulating coolant fluid in the charge air heat exchanger and / or the supply of recirculated exhaust gas, in particular recirculated exhaust gas at low pressure; said heating means is an electrical thermal resistance, in particular a thermal resistance, in particular an electrical resistance of the type with a positive temperature coefficient; - Said control means acts on said heating means so that the heating power delivered to the heat transfer fluid circulating in the independent flow circuit is constant; - The heat transfer fluid heating means is connected to the exhaust line of the gases of the heat engine via at least one heat exchanger taking calories from the exhaust gas.

[0015] The invention also relates to a vehicle, in particular a motor vehicle, characterized in that it comprises a device for thermal management of a charge air comprising at least any one of the aforementioned characteristics.

The invention will now be described in more detail but in a non-limiting manner with reference to the appended figures, in which: FIG. 1 is a schematic representation of an air circuit of an engine and of a device for thermal management of a charge air, according to the invention, [fig.1] FIG. 2 is a schematic representation of the device for thermal management of a charge air taken in isolation, in accordance with the invention.

In Figure 1 and Figure 2, a heat engine referenced 1 is associated with a thermal management device 10.

The engine cooling system 1 comprises a cooling circuit 2 in which a cooling liquid circulates.

In addition to the engine 1, the cooling circuit can also include an oil cooler and a gearbox (not shown) in order to perform thermal management of this equipment.

A pump (not shown) is used for circulating the coolant in the cooling circuit in order in particular to allow the coolant to flow between the inlet 5 and the outlet 6 of the engine water circuit.

The cooling circuit includes a coolant cooler which will also be qualified as a radiator because the ambient air is used for this cooling purpose.

This radiator thus allows the cooling fluid to enter into thermal exchange with the ambient air in order to be cooled there.

Such a radiator is generally placed on the front of the vehicle, at least in direct engagement with the ambient air in order to be passed through by the latter when the vehicle is moving.

A fan can also be used to force the circulation of ambient air through the radiator core.

The cooling circuit 2 is crossed by a heat transfer fluid whose temperature is between 60 and 100 ° C, preferably 90 ° C.

Because of this temperature value, the cooling circuit can be qualified as a high temperature circuit.

The cooling circuit also comprises a thermostat so that the coolant passes through the radiator as soon as the coolant reaches a set temperature, which makes it possible to regulate the temperature of the coolant to its nominal value only by cooling with ambient air.

The cooling circuit 2 is further connected to a heating branch in which is disposed an air heater (not shown) intended to heat the vehicle interior.

To prevent the cooling circuit from being pressurized too much, the latter includes a degassing box (not shown).

The engine 1 also has a turbocharger consisting of a turbine driven in rotation by the exhaust gases and mechanically connected in rotation by a drive shaft to a compressor making it possible to supply supercharging air to the engine I.

The turbocharger driven by the engine exhaust gases produces pressurized air, previously called charge air which circulates in a heat exchanger 4 between the charge air and a heat transfer fluid.

An independent flow circuit 3 of a heat transfer fluid comprises the heat exchanger 4.

The term “independent circuit” is understood to mean a hydraulic circuit the operation of which is not associated with that of the cooling circuit 2 of the engine.

In addition, the heat transfer fluid circulates only in independent circuit 3.

Coolant circulates in the engine cooling system.

The coolant can be water with glycol.

The heat transfer fluid can be water with glycol but also a different fluid, in particular a refrigerant.

The nominal temperature of the coolant of the independent circuit 3 is lower than the nominal temperature of the coolant, so that the independent circuit is sometimes called a low temperature circuit. 6

To regulate the temperature of the heat transfer fluid to a temperature threshold different from that of the coolant, the independent circuit comprises a radiator 35 whose beam is traversed by the ambient air to cool the heat transfer fluid.

The heat exchanger 4 comprises at least one tube 40 in which circulates the charge air which has a thermal relationship with at least one internal duct 37 of the heat exchanger 4 in which the heat transfer fluid circulates.

[0024] The heat exchanger 4 comprises an inlet 41 and an outlet 42 of charge air.

Input 41 is connected to the air compressor.

The outlet 42 is connected to the intake air manifold 7 of the engine 1.

The charge air is routed to the air manifold 7 of the engine 1 via a supply line 43 connected to the outlet 42 of the heat exchanger 4.

In nominal engine operation, after a start-up and temperature rise phase, the charge air is at a high temperature due to its compression which should be cooled by the heat exchanger 4 which is then comparable to a charge air cooler, also called RAS.

[0027] The RAS is a gas / liquid heat exchanger in which the coolant circulates when pump 33 is put into operation.

The independent circuit 3 is thus traversed by a heat transfer fluid maintained at low temperature by circulating through a radiator 35 in thermal exchange with the ambient air.

The independent circuit 3 preferably comprises a main loop 31 in which are arranged in this order the pump 33, the heat exchanger 4, the thermostat 34 and the radiator 35.

The independent circuit 3 comprises a bypass branch 32 connected to the main loop 31 by means of first and second junctions 321, 322 arranged respectively upstream of the thermostat 34 and downstream of the radiator 35.

[0030] Depending on the temperature of the heat transfer fluid at the thermostat 34, the heat transfer fluid circulates in the main loop 31 to be cooled there by the radiator 35.

As soon as the temperature reaches a predefined temperature threshold, the thermostat 34 opens the flow of heat transfer fluid to the radiator 35 to be cooled there by heat exchange with a cooling ah-.

Below the temperature threshold, the thermostat 34 is closed so that the coolant circulates through the bypass branch 32, so that the coolant rises in temperature more rapidly when the engine is started.

Such an advantage is sought after starting the engine, in particular during its temperature rise phase.

Such an advantage is also sought after in order to defrost the SAR, in particular rapidly.

The phenomenon of icing of the RAS appears when the hot supercharged air arrives on 7 of the internal walls of the RAS, causes a phenomenon of condensation and then of icing, in particular in the case where the temperature of the ambient air in which the vehicle has a negative outside temperature.

The phenomenon of icing is even more marked when the outside temperature is below -5 ° C.

To overcome the phenomenon of icing, which could be highly detrimental for the proper functioning of the engine, or even the starting of the latter, a heating means 20 is positioned in the independent circuit for the flow of the heat transfer fluid.

According to one embodiment as illustrated in Figure 1, said heating means 20 is disposed at the outlet of the heat exchanger 4.

According to an alternative embodiment, said heating means can be positioned at the inlet of the heat exchanger 4.

Said heating means may be of the type of a thermal resistance 21, more particularly an electrical resistance, as shown in FIG. 1.

A control means (not shown) controls the operation of resistor 20 in terms of duration and / or power.

The electrical resistance 20 can be self-adjusting in power.

It can be a resistor with a positive temperature coefficient.

In this case, the control means controls the electrical supply time of the resistance according to at least one parameter chosen from a predetermined operating time, an ambient temperature, a water temperature of circuit 3 or the use of recirculated gases. , for example.

[0037] The control means is connected directly or indirectly to an outside temperature sensor, to a temperature sensor 36 of the heat transfer fluid, or to a control / command computer (not shown) of the engine which notably controls the engine. operating state of a valve for recirculating all or part of the exhaust gases to the engine supply air compressor.

In the example of the device of FIG. 1 or of FIG. 2, the temperature sensor 36 of the heat transfer fluid is positioned downstream of said heating means 20, knowing that it can also be positioned upstream of the latter, or even at the inlet of the heat exchanger 4.

According to an alternative embodiment, said heating means 20 is an electrical resistance controlled by current by an appropriate control means intended to adjust the heating power according to at least one of the aforementioned parameters.

The thermal management device control method is implemented as soon as the thermal engine is started.

The implementation of the method consists of a first step of operating the water pump 33 which can be either driven by an electric motor, in particular a dedicated electric motor, or by a mechanical link connecting the pump. 8 water to a rotating part of the engine, for example a crankshaft wheel, by a drive belt.

The method of controlling the thermal management device comprises a step of measuring at least one of the aforementioned parameters.

Preferably, the ambient temperature as well as the temperature of the heat transfer fluid are operating parameters of the device which are taken continuously so that it is possible to obtain an instantaneous value of the parameters taken for controlling said heating means which are the ambient air temperature and heat transfer fluid temperature.

When the measured ambient air temperature value is less than a temperature threshold between 0 ° and 5 ° C, the control means performs a successive step of measuring the temperature of the heat transfer fluid.

When the measured value of the temperature of the heat transfer fluid is below a temperature threshold of between 0 ° and 15 ° C, simultaneously said heating means 20 is activated.

The temperature of the heat transfer fluid then being below the opening temperature threshold of the thermostat 34, the heat transfer fluid circulates in the bypass branch 32 of the radiator 35.

The calories from said heating means are sent directly to the internal ducts 37 of the heat exchanger 4 to counter the effect of icing of the condensation water provided by the circulation of a charge air in the tubes 40 of the. heat exchanger 4.

By way of example, said heating means 20 is able to supply a power of between 200 W and 800 W, preferably 500 W.

[0045] By way of example, the heating time is between 200 s and 500 s, preferably 350 s.

The implementation of the device allows evaporation of the condensation water inside the RAS of between 60 and 90%, preferably 80%.

For example, the implementation of the device of the invention allows a reduction in the amount of condensed water from 59 g to 13 g.

The main loop 31 of the device comprises a cooler, in particular a radiator 35 intended to be traversed by the heat transfer fluid when the temperature of the heat transfer fluid reaches the predetermined opening value of the thermostat 34.

Therefore this temperature value of the heat transfer fluid in the cooler so that the temperature of the heat transfer fluid is maintained at a nominal value between 30 ° C and 60 ° C, preferably 40 ° C.

Figure 2 illustrates an alternative embodiment of the device of the invention, namely that said heating means 20 of the heat transfer fluid is connected to the exhaust line 44 of the exhaust gases by means of at least one heat exchanger, part of the bundle of which consists of first heat transfer fluid circulation tubes 22 and of which a second part of the bundle consists of second exhaust gas circulation tubes 23.

Said heating means 20 is a gas exchanger intended to operate a heat exchange between heat transfer fluid and the exhaust gases.

In order to increase the calories to be transmitted, the exhaust line 44 on which said heating means 20 is partly mounted is connected to the exhaust manifold 8.

Preferably, said heating means comprises insulation means making it possible to stop the heat exchange between the heat transfer fluid and the exhaust gases when the heat transfer fluid circulates through the radiator 35.

To this end, the device comprises isolation means (not shown) such as a valve actuated between closed and open states by said control means.

According to another variant embodiment (not shown), said heating means 20 of the heat transfer fluid is connected to an air conditioning circuit of the vehicle interior, in particular to a heat pump, via a heat exchanger a part of the bundle of which consists of first heat transfer fluid circulation tubes and a second part of the bundle of which consists of second refrigerant fluid circulation tubes.

The operation of the air conditioning circuit in heat pump mode allows said heating means 20 to be likened to a water condenser in that the heat transfer fluid is heated by the refrigerant fluid.

Whatever the embodiment of the device of the invention, it prevents icing of the RAS, a controlled temperature rise of the engine due to optimized management of the temperature of the intake air.

The advantage is thus found in an improved operation of the supercharged engine, whatever the ambient air temperature.

The air intake line is not blocked by the presence of frost in the RAS.

The water content of the supercharged intake air is reduced, which tends to improve engine efficiency and reduce pollutant emissions.

The independent circuit 3 for the flow of a heat transfer fluid has an operating temperature lower than the engine cooling circuit, so that it is possible to use a heat transfer fluid having other property, in particular containing capsules comprising a phase change fluid to heat the RAS even more quickly.

The fact that the cooling circuits of the RAS and of the engine are dissociated from one another, the quantity of coolant circulating in the cooling circuit of the RAS is less, which opens up new perspectives of choice as regards the cooling fluid. cooling of the RAS.

The advantages of the present invention are numerous.

These include, among others: - a potential for reducing fuel consumption by the rapid rise in temperature of the engine, - at specific times, such as regeneration of the particulate filter where a high temperature is required, heating of the engine. The intake air can allow a warmer intake air favoring the operation of the various pollution control devices, - a potential for reducing carbonic acid and carbon monoxide emissions for a faster rise of the engine in its phase of temperature rise, - for cooling the charge air, a reduction potential of nitrogen oxides.

11 [Claim 1] [Claim 2] [Claim 3] [Claim 4] [Claim 5] [Claim 6]

Claims (1)

Device (10) for thermal management of an engine (1), in particular of a combustion engine for a vehicle, comprising an engine cooling circuit (2) and an independent flow circuit (3) of a fluid coolant circulating in a heat exchanger (4) through which a charge air intended to supply the heat engine with intake gas, this heat exchanger (4) being traversed by a heat transfer fluid, characterized in that it comprises a means of heating (20) of the heat transfer fluid intended to transmit calories to the heat exchanger (4), in particular when the engine is started and / or under the condition of icing temperature of the internal walls of the heat exchanger. Device (10) according to the preceding claim, characterized in that the independent flow circuit (3) of a heat transfer fluid comprises a main loop (31) comprising a water pump (33), the heat exchanger (4) between the charge air and the coolant, a thermostat (34), a cooler (35) for the coolant, as well as a bypass branch (32) of the cooler connected to the main loop by first and second junctions ( 321, 322) respectively arranged upstream of the thermostat (34) and downstream of the cooler (35), in a direction of flow of the heat transfer fluid in the flow circuit. Device (10) according to the preceding claim, characterized in that the heating means (20) is arranged downstream of the heat exchanger (4) so that the supply of calories is controlled by the elements of the independent circuit of flow of the heat transfer fluid, in particular the thermostat (34) and / or the cooler (35). Device (10) according to claim 1 or 2, characterized in that the heating means (20) is arranged upstream of the heat exchanger (4) so that the calorie supply of the heating means (20) is directly transmitted to the heat exchanger. Device (10) according to Claim 3 or 4, characterized in that the heating means (20) is implemented when the engine is started cold. Device (10) according to any one of the preceding claims, characterized in that it comprises means for controlling said heating means (20) integrating a storage memory in which is stored 12 [Claim 7] [Claim 8] [Claim 9] [Claim 10] [Claim 11] registered at least one operating parameter of said heating means, in particular an operating time or a heating power of said heating means. Device (10) according to the preceding claim, characterized in that said control means of said heating means (20) adjusts the activation time and / or the power of said heating means in a variable manner according to at least one operating parameter of the vehicle, in particular the ambient temperature and / or the temperature of the heat transfer fluid circulating in the charge air heat exchanger (4) and / or the supply of recirculated exhaust gas, in particular recirculated exhaust gas at low pressure. Device (10) according to any one of the preceding claims, characterized in that said heating means (20) is an electrical thermal resistance (21), in particular a thermal resistance, in particular an electrical resistance of the type with a positive temperature coefficient. Device (10) according to one of claims 6 to 8, characterized in that said control means acts on said heating means so that the heating power delivered to the heat transfer fluid circulating in the independent flow circuit (3) is constant. Device (10) according to any one of claims 1 to 7, characterized in that the heating means (20) of the heat transfer fluid is connected to the exhaust line (44) of the gases of the heat engine by means of 'at least one heat exchanger (23) taking calories from the exhaust gas. Vehicle, in particular motor vehicle, characterized in that it comprises at least one device (10) for thermal management of charge air according to any one of the preceding claims.