FR2884865A1 - Cooling device for e.g. petrol engine, has main coolant circuit with radiator, and auxiliary cooling circuit, with cooler and pump, connected to part of radiator whose cooling capacity is greater than that of another part of radiator - Google Patents

Abstract

The device has a main coolant circuit (1) traversing an engine (2) of a motor vehicle. The circuit (1) has a circulation pump (3), a thermostatic valve (4) and a radiator (10). An auxiliary cooling circuit (6) has an auxiliary cooler (7) cooling a unit of the vehicle, and an auxiliary pump (8). The circuit (6) is connected to a part (9) of the radiator whose cooling capacity is greater than that of another part (5) of the radiator. The pump (8) circulates a part of the coolant inside the cooler (7) and across the part (9) when the valve is closed. An independent claim is also included for a cooling method for a motor vehicle.

Description

Device and method for cooling the motor and a

vehicle 5

  The present invention relates to the field of motor vehicle engine cooling in particular for also cooling certain vehicle components, such as a partial exhaust gas recirculation device.

  The drive motor of motor vehicles can be cooled by circulating a heat-transfer coolant, in practice water, which passes through the main parts of the engine to be cooled. The cooling circuit essentially includes a circulation pump driven by the engine and a radiator consisting of a water / air heat exchanger capable of cooling the water circulated by the pump. A thermostatic valve is also generally provided, so as to isolate the part of the main cooling circuit which contains the radiator during the cold start period where excessive cooling of the motor is not desired. The thermostatic valve opens gradually according to the temperature of the circulating water, warmed by the engine after the start-up period.

  In addition, the exhaust gases reintroduced into the combustion chamber serve to reduce the maximum combustion temperature. The emission of nitrogen oxides increases faster than the combustion temperature, the recirculation of the gases has, as a measure of the reduction of the temperature, an effective method to decrease the emissions of oxides of nitrogen. The cooling of the recycled gases thus makes it possible to increase the effect of reducing the amount of nitrogen oxides while maintaining an unchanged particle emission.

  Generally, the recycled gases pass through a heat exchanger for cooling purposes. Patent applications FR 2 812 027 (Daimler-Chrysler) and FR 2 830 929 (Denso) deal with particular constructions of exhaust gas heat exchangers, but do not describe a link between the regulation of the cooling of the engine and the regulation of exhaust gas cooling, with a view to their depollution.

  The invention proposes a device and a method for cooling an engine and a motor vehicle member which solves these disadvantages in a particularly simple manner. The invention proposes in particular a method which promotes the rapid rise of the engine temperature, which cools the body of the vehicle especially when the engine is at low temperature, and which optimizes the cooling of the engine at high temperature.

  According to one embodiment of the invention, the cooling device for a motor vehicle comprises a main coolant circuit, passing through a motor and equipped with a circulation pump, a thermostatic valve and a radiator, said device comprising an auxiliary cooling circuit of a vehicle member comprising an auxiliary cooler and an auxiliary pump, characterized in that the auxiliary cooling circuit is connected to a second radiator whose cooling capacity is greater than that of the radiator.

  The cooling device proposed may have the following characteristics, individually or in combination: the auxiliary pump is adapted to circulate a part of the coolant in the auxiliary cooler and through the second radiator, when the thermostatic valve is closed, first radiator and the second radiator are associated in a single radiator and separated by a partition 10 provided with a second thermostatic valve, the single radiator comprises a plurality of parallel passages, and the ends of which open into two water boxes, one at least water boxes being separated by the partition, - the second radiator is traversed by the coolant, in one direction or another depending on whether the second thermostatic valve is open or closed, - the coolant is water and that the opening temperature of the radiator thermostatic valve is between 80 C and 90 C, and preferably of the order of 83 ° C., the opening temperature of the second thermostatic valve of the second radiator is greater than the opening temperature of the radiator thermostatic valve and is between 88 ° C. and 100 ° C. , and preferably of the order of 89 C, the aforementioned member is a device for partial recycling of the exhaust gas, and the aforementioned member is an alternator-starter or a gearbox.

  The present invention furthermore relates to a cooling method for a motor vehicle in which, when the engine temperature is above a high temperature threshold, a heat transfer fluid is circulated through the engine and a single radiator, characterized in that that as long as the engine temperature remains below the high temperature threshold, a part of the coolant is circulated out of the engine through an auxiliary cooler of a partial exhaust gas recirculation device, and through the second radiator.

  Advantageously, the method uses an auxiliary pump to circulate the coolant in the auxiliary cooler.

  Advantageously, the method comprises the step of, when the engine temperature is greater than a predetermined intermediate limit, less than or equal to the high temperature threshold, circulating the heat transfer fluid through the engine and through a radiator of lower heat capacity. to that of the radiator.

  The fact of having a second radiator makes it possible to overlap the behavior of the device operating with a motor at low temperature and that operating with a motor at high temperature. At medium temperature, it is interesting to start cooling the engine, without stopping the clean-up cycle by cooling the exhaust gas for recycling.

  Other characteristics and advantages of the invention will appear on reading the detailed description of an embodiment taken by way of non-limiting example, in conjunction with the accompanying drawings, in which the single FIG. 1 is a diagrammatic representation. of a cooling device of a first embodiment of the invention, As illustrated in Figure 1, the cooling device comprises a main circuit 1 of heat transfer fluid passing through the engine 2. The heat transfer fluid is generally of the water, with anti-freeze additives. The main circuit 1 is equipped with a circulation pump 3, a first thermostatic valve 4 and a radiator 10. An auxiliary circuit 6 comprises an auxiliary pump 8 and an auxiliary cooler 7 for cooling a vehicle body. The radiator 10 comprises a plurality of parallel passages 13 whose all of the ends 15 on one side open into a downstream water box 17 and the set of ends 14 on the other side opens into an upstream water box 16. The upstream water box 16 is divided into two zones by a partition 11 provided with a second thermostatic valve 12. A first zone 18 has a first opening 21 connected to a pipe of the main circuit 1. A second zone 23, of larger dimensions at the first, has a second opening 24. The downstream water box 17 has a main opening 19 connected to the main circuit 1, and an auxiliary opening 20 connected to the auxiliary cooling circuit 6.

  The passages 13 may be cylindrical tubes, or plates of any other cross section, able to pass the heat transfer fluid. The passages are made of thermally conductive materials and are surrounded by cooling fins 22 so as to promote the heat exchange between the outside air and the coolant. The cooling capacity of the radiator 10 is all the more important that the outside air is cold and passes through the fins 22 of the radiator 10 at high speed, the heat transfer fluid is at a high temperature and the flow of heat transfer fluid through the radiator 10 is important.

  The upstream water box 16 has two portions, a portion containing the ends of the passages opening into the main zone 23 and a portion corresponding to the second zone 18. The part of the radiator 10 comprising the opening 21, the zone 18 of the box upstream water 16, the corresponding passages 13 and the corresponding portion of the downstream water box 17, forms a portion 5 of the radiator 10. Similarly, the opening 24, the main zone 23, the corresponding passages 13 and the corresponding portion of the downstream water box 17, form a second portion 9 of the radiator 10. In the embodiment illustrated in Figure 1, the upstream connection of the two parts 5 and 9 of the radiator 10 takes place inside the box. upstream water 16, and the two openings 21 and 24 make it possible to connect the two radiator parts 5 and 9 respectively to the main circuit 1 and to the auxiliary circuit 6.

  The partition 11 separates the two portions 5 and 9 of the upstream water box 16. The two portions of the upstream water box 16 are separated by a second thermostatic valve 12. This provides an additional degree of freedom to adjust the flows in the different circuits of the device.

  The invention is particularly useful when the vehicle member needs to be particularly cooled when the engine is cold. This is the case of partial exhaust gas recirculation units.

  The main circuit 1 may also comprise other elements not shown in FIG. 1, such as expansion vessels which make it possible to maintain the pressure of the heat transfer fluid inside the cooling device so that the water can flow through the device up to about 115 C without being boiling.

  In the device described, the second thermostatic valve 12 opens when the engine temperature reaches a high temperature threshold which is between 88 C and 100 C and preferably of the order of 89 C. The first thermostatic valve 4 s 'opens when the engine temperature reaches an intermediate limit of between 80 C and 90 C and preferably of the order of 83 C. For the remainder of the description, will call low temperature the temperature between the ambient temperature and the limit intermediate. The average temperature will be called the temperature between the intermediate limit and the high temperature threshold, and the temperature above the high temperature threshold.

  We will now describe the cooling process for a motor vehicle in a phase where the engine is at a low temperature. The two thermostatic valves 4 and 12 are closed so that the coolant does not flow through the engine 2, and the circulation pump 3 is inactive. Under these conditions, all the calories generated by the combustion of the engine 2 of the vehicle, whether it is a gasoline engine or a diesel engine, is used to heat the engine 2 as quickly as possible. During this phase, the auxiliary pump 8 is in operation and circulates the coolant inside the auxiliary cooler 7 and, through the opening 20, through the radiator 10. The heat transfer fluid circulates through the passages 13 of the main part 9 of the radiator 10, out of the radiator 10 by the upstream water box 16 and the opening 24, and joined the auxiliary circuit 6. It could also be conceived that the auxiliary pump 8 circulates the heat transfer fluid in the other direction , that is to say going from the opening 24 to the opening 20, then through the auxiliary cooler 7.

  When the engine temperature reaches the intermediate limit, the thermostatic valve 12 is always closed while the thermostatic valve 4 opens. The circulation pump 3 then circulates the heat transfer fluid through the main circuit 1 and the part 5 of the radiator 10 so that the heat transfer fluid reaches the main circuit 1 through the opening 19. During this average temperature phase, the engine 2 is only cooled by the part 5 of the radiator 10. the auxiliary pump 8 is still in action and the main part 9 of the radiator 10 is used to cool the coolant circulating inside the auxiliary cooler 7.

  When the engine temperature is above the high temperature threshold, the two thermostatic valves 4 and 12 are open and the flow inside the main circuit 1 enters the upstream water box 16 of the radiator 10. heat transfer fluid is shared through the thermostatic valve 12 located on the partition 11 in the radiator 10, and through the parts 5 and 9 of the radiator 10 to exit through the opening 19 and join the main circuit 1. When the auxiliary cooler 7 is associated with a partial exhaust gas recycling device, the coolant no longer crosses the auxiliary circuit 6 and the auxiliary pump 8 is stopped, so that the entire heat capacity of the radiator 10 is fully used to cool the engine 2.

  In the embodiment illustrated in FIG. 1, the main part 23 is used when the engine 2 is at low temperature, for cooling exhaust gases intended to be recycled at the intake of the engine while the engine is isolated for allow its warming as fast as possible.

  The optimized heating of the engine can also be used to power a heater for heating the passenger compartment and for which it is desired to obtain as quickly as possible an increase in the temperature of the coolant at 70 C. At high temperature, the radiator 10 is then used mainly to cool the engine 2.

  The cooler 7 may be used for cooling high temperature vehicle components such as a device for recovering part of the exhaust gas (EGR) for recycling at the intake of the engine or another organ of the vehicle such as an alternator-starter. It could also be conceived to cool other organs such as the vehicle gearbox.

Claims (11)

  1. Cooling device for a motor vehicle comprising a main circuit (1) of coolant, passing through the engine (2) and equipped with a circulation pump (3), a thermostatic valve (4) and a radiator (5), said device comprising an auxiliary cooling circuit (6) of a vehicle member comprising an auxiliary cooler (7) and an auxiliary pump (8), characterized in that the auxiliary cooling circuit (6) is connected a second radiator (9) whose cooling capacity is greater than that of the radiator (5).   2. Cooling device according to claim 1, characterized in that the auxiliary pump (8) is adapted to circulate a portion of the coolant in the auxiliary cooler (7) and through the second radiator (9), when the valve thermostatic (4) is closed.   3. Cooling device according to one of claims 1 or 2, characterized in that the first radiator (5) and the second radiator (9) are associated in a global radiator (10) and separated by a partition (II) provided a second thermostatic valve (12).   4. Cooling device according to one of the preceding claims, characterized in that the global radiator (10) comprises a plurality of parallel passages (13), and whose ends (14, 15) open into two water boxes (16). , 17), at least one (16) of the water boxes (16, 17) being separated by the partition (11).   5. Cooling device according to one of the preceding claims, characterized in that the second radiator (9) is traversed by the coolant in one direction or another depending on whether the second thermostatic valve (12) is open or closed .   Cooling device according to one of the preceding claims, characterized in that the coolant is water and that the opening temperature of the thermostatic valve (4) of the radiator (5) is between 80 C and 90 C, and preferably of the order of 83 C.   Cooling device according to one of the preceding claims, characterized in that the opening temperature of the second thermostatic valve (12) of the second radiator (9) is greater than the opening temperature of the thermostatic valve (4). ) of the radiator (5) and is between 88 C and 100 C, and preferably of the order of 89 C.   8. Cooling device according to one of the preceding claims, characterized in that the aforementioned member is a device for partial recycling of the exhaust gas.   9. Cooling device according to one of claims 1 to 7, characterized in that the aforementioned member is an alternator-starter or a gearbox.   10. A cooling method for a motor vehicle in which, when the temperature of the engine (2) is above a high temperature threshold, a heat transfer fluid is circulated through the engine (2) and a global radiator (10). ), characterized in that as long as the engine temperature remains below the high temperature threshold, a part of the coolant is circulated out of the engine through an auxiliary cooler (7) of a device for partial recycling of the heat transfer medium. exhaust gas, and through the second radiator (9).   11. The method of claim 10, characterized in that an auxiliary pump (8) is used to circulate the coolant in the auxiliary cooler (7).   2. Method according to one of claims 1 0 or 1 1, characterized in that when the temperature of the motor (2) is greater than a predetermined intermediate limit, less than or equal to the high temperature threshold, the fluid is circulated. coolant through the engine (2) and through a radiator (5) of heat capacity less than that of the radiator (9).