FR3058786B1 - THERMAL EXCHANGER AND DEVICE FOR COOLING LUBRICATING OIL IN A THERMAL ENGINE - Google Patents

Abstract

The exchanger (1) comprises a plurality of stacked plates defining between them a plurality of interplate spaces (1a, 2a, 3a, 1b, 2b, 3b, 1c, 2c, 3c), fluid inlet ducts (CE1 , CE2, CE3) and fluid outlet ducts (CS1, CS2, CS3) placing interplate spaces in communication with one another to create first and second heat exchange circuits, the first heat exchange circuit being intended lubricating oil (TBV) and the second heat exchange circuit being for a first cooling fluid (RE1). According to the invention, the exchanger comprises a third heat exchange circuit for a second cooling fluid (RE2).

Description

THERMAL EXCHANGER AND DEVICE FOR COOLING LUBRICATING OIL IN A THERMAL ENGINE

[001] The invention relates generally to the field of the automobile. More particularly, the invention relates to a heat exchanger for cooling the lubricating oil in a motor vehicle engine. The invention also relates to a lubricating oil cooling device incorporating said heat exchanger.

[002] In the context of the reduction of polluting emissions from motor vehicles, the European emission standards, known as "Euro" standards, impose sharp reductions in the acceptable limits for these discharges. Between the "Euro 1" standard and the "Euro 7" standard, for the CO2 rate in particular, emissions are expected to fall by around 80% for diesel engines and around 60% for diesel engines. gasoline engines.

[003] The loss of mechanical energy by friction in the engine of a motor vehicle is of the order of 20% of the total energy released by the combustion of the fuel. The reduction of mechanical friction in the engine is therefore a goal for car manufacturers to reduce emissions.

[004] The use of a very low viscosity oil is a solution envisaged to obtain a reduction in fuel consumption and correspondingly a decrease in pollutant emissions. However, the oil with very low viscosity poses additional constraints in terms of control of its operating temperature for the desired viscosity and to prevent premature aging. Thus, an oil with very low viscosity will typically not exceed an operating temperature of about 125 ° C to maintain a viscosity of 4cSt, while the lubricating oils currently used in heat engines can maintain a viscosity of 4cSt up to a temperature of the order of 145 ° C.

[005] By the document JP93836274 of the prior art, it is known a plate heat exchanger for cooling the lubricating oil of a heat engine. The exchanger has several stacked exchange plates and integrates two separate and distinct fluid circuits. In this heat exchanger, one of the circuits is dedicated to the lubricating oil to be cooled and the other circuit to a coolant such as that of the engine.

The exchangers of the prior art, such as that described in JP93836274, find applications in the cooling devices for the lubricating oils currently used, but are not suitable for very low viscosity oils because their cooling capacity remains limited. .

[007] It now appears desirable to provide a new type of heat exchanger with increased cooling capacity, making it suitable for cooling very low viscosity oils in thermal engines.

According to a first aspect, the invention relates to a heat exchanger for cooling the lubricating oil of a heat engine, the exchanger comprising a plurality of stacked plates defining between them a plurality of interplate spaces, ducts. fluid inlet and fluid outlet conduits interconnecting interplate spaces therebetween to create first and second heat exchange circuits, the first heat exchange circuit being for the lubricating oil and the second heat exchange circuit being intended for a first cooling fluid. According to the invention, the exchanger comprises a third heat exchange circuit for a second cooling fluid.

[009] This architecture of the exchanger according to the invention with two heat exchange circuits dedicated to two separate cooling fluids, allows the use of the exchanger for cooling a lubricating oil with very low viscosity.

According to a particular characteristic, the heat exchanger comprises first, second and third fluid inlet ducts and first, second and third fluid outlet ducts for the first, second and third heat exchange circuits, respectively.

According to another particular characteristic, the heat exchanger comprises nine interplate spaces, each of the first, second and third heat exchange circuits comprising three dedicated interplate spaces.

According to another aspect, the invention also relates to a cooling device of the lubricating oil of a motor vehicle engine. According to the invention, the lubricating oil cooling device comprises a heat exchanger as briefly described above, a first lubricating oil circulation circuit established through the exchanger and connected to a lubrication device. of the heat engine, a second circulation circuit of a first cooling fluid established through the exchanger and connected to a first cooling device of the vehicle, and a third circulation circuit of a second circulating fluid established through the exchanger and connected to a second cooling device of the vehicle.

According to another particular embodiment, the lubricating oil cooling device also comprises a thermostat device controlling the circulation in the third circuit of the second cooling fluid as a function of the temperature of the lubricating oil.

According to a first particular embodiment, the first cooling fluid is a high temperature coolant and the first cooling device of the vehicle is the cooling device of the heat engine, and the second circulation fluid is a liquid. cooling system and the second vehicle cooling device is an auxiliary cooling device thereof.

According to a second particular embodiment, the first cooling fluid is a high temperature coolant and the first cooling device of the vehicle is the cooling device of the heat engine, and the second circulation fluid is a liquid. refrigerant and the second cooling device of the vehicle is an air conditioning device thereof.

According to a third particular embodiment, the first cooling fluid is a coolant at low temperature and the first cooling device of the vehicle is an auxiliary cooling device, and the second circulation fluid is a refrigerant and the second cooling device of the vehicle is an air conditioning device thereof.

Other advantages and features of the present invention will appear more clearly on reading the description below of several particular embodiments of the invention with reference to the accompanying drawings, in which: FIG. simplified sectional view showing the architecture of a particular embodiment of a heat exchanger according to the invention; Fig.2 is a simplified top view of the heat exchanger according to the invention of Fig.1; Fig.3 is a block diagram showing a first particular embodiment of a lubricating oil cooling device according to the invention; and Fig.4 is a block diagram showing a second particular embodiment of a lubricating oil cooling device according to the invention; Referring to Figs.1 and 2, there is described below a particular embodiment 1 of a heat exchanger according to the invention.

The heat exchanger 1 is a plate heat exchanger. This type of exchanger allows a very large compactness. This facilitates its integration into the engine compartment of the motor vehicle.

In known manner, the heat exchanger 1 is formed from a stack of similar plates, typically rectangular, keeping between them interplate spaces allowing fluid circulation and heat exchange between them. Inlet ducts and fluid outlet ducts are arranged transversely to the plane of the plates and put in communication interplate spaces between them to create heat exchange circuits. The mechanical fastening of the assembly thus formed and the sealing of the heat exchange circuits are typically obtained by brazing or welding the plates together at their flanks, in their circumferences, and ducts to the plates at the orifices. crossing ducts.

According to the invention, the heat exchanger 1 is provided for the circulation of three separate fluids, namely, the lubricating oil TBV to be cooled and first and second cooling fluids RE1 and RE2.

As shown in Figs.1 and 2 in this embodiment, the heat exchanger 1 comprises a plurality of nine interplate spaces 1a, 1b, 1c, 2a, 2b, 2c and 3a, 3b, 3c, and ducts. CE1, CE2, CE3 and CS1, CS2, CS3 flow of fluids. Of course, the number of interplate spaces and the number of inlet and outlet ducts will depend on the application of the exchanger according to the invention, specifically the exchange surface required for a heat output to be evacuated.

Interplate spaces 1a, 1b and 1c are dedicated to the lubricating oil TBV. These interplate spaces 1a, 1b and 1c are in communication with each other through the inlet ducts CE1 and outlet CS1 and form a sealed thermal exchange circuit of the oil TBV with the cooling fluids RE1 and RE2.

Interplate spaces 2a, 2b and 2c are dedicated to the first cooling fluid RE1. These interplate spaces 2a, 2b and 2c are in communication with each other through the inlet ducts CE2 and outlet CS2 and form a thermal exchange circuit of the cooling fluid RE1 with the oil TBV and the cooling fluid RE2.

The interplate spaces 3a, 3b and 3c are dedicated to the second cooling fluid RE2. These interplate spaces 3a, 3b and 3c are in communication with each other through the inlet ducts CE3 and outlet CS3 and form a thermal exchange circuit of the cooling fluid RE2 with the oil TBV and the cooling fluid RE1.

As shown in Fig.1, the interplate spaces are superimposed, vertically in the example of Fig.1, and in thermal contact with each other through the plates and the input ducts CE and CS output. . In this embodiment, from top to bottom in FIG. 1, the superposition of the interplate spaces is the following: - 1a (TBV oil), 2a (fluid RE1), 3a (fluid RE2), - 1b (TBV oil) , 2b (fluid RE1), 3b (fluid RE2), - 1c (oil TBV), 2c (fluid RE1), 3c (fluid RE2).

The heat exchanger 1 according to the invention can be integrated in different embodiments of a cooling device of the lubricating oil of the heat engine.

Referring also to Fig.3, there are now described three variants of a first embodiment 4A of a lubricating oil cooling device incorporating the heat exchanger 1 according to the invention.

The lubricating oil cooling device 4A comprises the heat exchanger 1 in which are established three fluid circulation circuits.

A first circuit C1 is the circulation circuit of the lubricating oil TBV to be cooled. This first circuit C1 is connected to the lubrication device 5 of the engine and allows cooling of the TBV oil. A second circuit C2 is the circulation circuit of the first circulation fluid RE1 which is connected to a first cooling device 6. A third circuit C3 is the circulation circuit of the second circulation fluid RE2 which is connected to a second cooling device 7.

According to a first variant, the first circulation fluid RE1 is a high temperature coolant and the second circulation fluid RE2 is a coolant at low temperature.

In this first variant, the high temperature coolant is typically that used for thermal management of the engine and cooled by the main radiator of the vehicle which is located on the aerothermal facade thereof. The first cooling device 6 is here the conventional pressurized cooling device of the heat engine to which the circuit C2 is connected.

The coolant at low temperature is here used in the second cooling device 7 which is connected to the circuit C3. In this first variant, the second cooling device 7 is for example an auxiliary cooling device used for cooling an electric motor in a hybrid vehicle. Typically, it is a non-pressurized cooling device equipped with a dedicated electric pump and a dedicated radiator which is located on the aerothermal facade of the vehicle.

According to a second variant, the first circulation fluid RE1 is the high temperature coolant described above and the second circulation fluid RE2 is the refrigerant flowing in the air conditioning device of the vehicle.

In this second variant, the device 6 is, as in the first variant, the conventional pressurized cooling device of the engine and the device 7 is the air conditioning device of the vehicle.

According to a third variant, the first circulation fluid RE1 is the low temperature coolant described above and the second circulation fluid RE2 is the refrigerant flowing in the air conditioning device of the vehicle.

In this third variant, the device 6 is the auxiliary cooling device described above in the first variant and the device 7 is, as in the second variant, the air conditioning device of the vehicle.

Referring now to Fig.4, there is now described a second embodiment 4B of the lubricating oil cooling device of the invention. In this embodiment 4B, the cooling of the lubricating oil TBV is regulated by an all-or-nothing type control of the circulation of the second cooling fluid RE2 in the circuit C3 of the heat exchanger 1, for example by means of a pilot thermostat of wax capsule type.

In the lubricating oil cooling device 4B, in addition to the heat exchanger 1, there is provided a thermostat device 8 for regulating the cooling of the lubricating oil TBV.

Fig.4 schematically shows the thermostat device 8. The circulation of the second cooling fluid RE2 is allowed in the circuit C3 by the device 8 (arrow path solid line) when the temperature of the oil TBV reaches a defined temperature threshold corresponding to a state switching temperature of the thermostat device 8. The circulation of the second cooling fluid RE2 is not allowed in the circuit C3 by the device 8 (dotted line arrow path) as long as the The temperature of the TBV oil remains below the set temperature threshold.

In another embodiment, the thermostat device 8 may take the form of a solenoid valve which is controlled by a control signal delivered by the engine control unit of the vehicle, said unit having a measurement of temperature of the TBV oil. Or, the solenoid valve can be driven locally from an oil temperature information provided by a sensor integrated in the heat exchanger 1. It will be noted that regardless of the embodiment of the thermostat device 8, solenoid valve controlled or controlled thermostat, the cooling can be achieved gradually.

It will be noted that the first, second and third variants of the lubricating oil cooling device 4A, described above, are also feasible with the lubricating oil cooling device 4B. According to that of the above three variants which is considered, it is the circulation of the cooling liquid at low temperature or that of the cooling refrigerant liquid which is controlled by the thermostat device 8.

Of course, the invention is not limited to the particular embodiments which have been described here by way of example. Those skilled in the art, according to the applications of the invention, may make various modifications and variations that fall within the scope of the appended claims.

Claims (9)

claims 1. Heat exchanger for cooling the lubricating oil of a heat engine, said exchanger (1) comprising a plurality of stacked plates defining between them a plurality of interplate spaces (1a, 2a, 3a; 1b, 2b, 3b 1c, 2c, 3c), fluid inlet ducts (CE1, CE2, CE3) and fluid outlet ducts (CS1, CS2, CS3) communicating said interplate spaces (1a, 1b, 1c, 2a; , 2b, 2c; 3a, 3b, 3c) between them to create first (1a, 1b, 1c, CE1, CS1) and second (2a, 2b, 2c, CE2, CS2) heat exchange circuits, said first circuit heat exchange (1a, 1b, 1c, CE1, CS1) being intended for said lubricating oil (TBV) and said second heat exchange circuit (2a, 2b, 2c, CE2, CS2) being intended for a first fluid cooling device (RE1), characterized in that it comprises a third heat exchange circuit (3a, 3b, 3c, CE3, CS3) intended for a second cooling fluid ent (RE2) and in that it comprises nine interplate spaces (1a, 2a, 3a; 1b, 2b, 3b; 1c, 2c, 3c), each of said first, second and third heat exchange circuits comprising three dedicated interplate spaces (1a, 1b, 1c; 2a, 2b, 2c; 3a, 3b, 3c). 2. Heat exchanger according to claim 1, characterized in that it comprises first, second and third fluid inlet ducts (CE1, CE2, CE3) and first, second and third fluid outlet ducts (CS1, CS2, CS3) for said first, second and third heat exchange circuits, respectively. 3. Device for cooling the lubricating oil of a motor vehicle engine, characterized in that it comprises a heat exchanger (1) according to any one of claims 1 to 2, a first circuit (C1). lubricating oil circulation system established through said exchanger (1) and connected to a lubrication device (5) of said engine, a second circuit (C2) for circulating a first cooling fluid (RE1) established through said exchanger (1) and connected to a first cooling device (6) of said vehicle, and a third circuit (C3) for circulating a second circulation fluid (RE2) established through said exchanger (1) and connected to a second cooling device (7) of said vehicle. 4. lubricating oil cooling device according to claim 3, characterized in that it also comprises a thermostat device (8) controlling the circulation in said third circuit (C3) of said second cooling fluid (RE2) in function the temperature of said lubricating oil (TBV). A lubricating oil cooling device according to claim 3 or 4, characterized in that said first cooling fluid (RE1) is a high temperature coolant and said first cooling device (6) of said vehicle is the cooling device of said heat engine, and said second circulation fluid (RE2) is a coolant at low temperature and said second cooling device (7) of said vehicle is an auxiliary cooling device thereof. A lubricating oil cooling device according to claim 3 or 4, characterized in that said first cooling fluid (RE1) is a high temperature coolant and said first cooling device (6) of said vehicle is the cooling device of said heat engine, and said second circulation fluid (RE2) is a refrigerant and said second cooling device (7) of said vehicle is an air conditioning device thereof. A lubricating oil cooling device according to claim 3 or 4, characterized in that said first cooling fluid (RE1) is a low temperature coolant and said first cooling device (6) of said vehicle is a auxiliary cooling device, and said second circulation fluid (RE2) is a refrigerant and said second cooling device (7) of said vehicle is an air conditioning device thereof. Lubricating oil cooling device according to one of claims 3 to 7, characterized in that said lubricating oil is a very low viscosity lubricating oil (TBV). 9. Motor vehicle characterized in that it comprises a cooling device of the lubricating oil of the engine according to any one of claims 3 to 8.