FR2917124A1 - Internal combustion engine cooling circuit for motor vehicle, has charge air cooler and recirculated exhaust gas coolers regrouped in same cooling module, and respectively having covers that are mutually fixed by soldering - Google Patents

Abstract

The circuit has a charge air cooler (26) and two recirculated exhaust gas coolers (40, 46) that are respectively cool recirculated exhaust gas at a lower pressure and at a high pressure. The coolers are regrouped in same cooling module (48), and respectively have covers (50, 66, 68) that respectively house heat exchange bodies, where the covers are mutually fixed by soldering. The covers (66, 68) are parallelepiped in shape, and are placed parallel to each other.

Description

Cooling circuit for charge air and gases

  The invention relates to the cooling of internal combustion engines, in particular for motor vehicles.

  It relates more particularly to a cooling circuit for an internal combustion engine, of the type comprising a first cooler which is a charge air cooler, a second cooler which is a recirculated exhaust cooler 15 at low pressure and a third cooler which is a high pressure recirculated exhaust gas cooler.

  To cool and increase the charge air density of an internal combustion engine, it is known to use a charge air cooler in which a liquid such as water is used as a fluid. coolant.

  Furthermore, to reduce the pollutant emissions of an internal combustion engine, it is known to take a portion of the exhaust gas for reinjection into the fresh air intake. To ensure proper filling of the engine cylinders and protecting the elements of the intake line, these gases are then cooled by water exchangers, referred to as recirculated exhaust gas coolers. In order to reinject hot exhaust gases with a sufficient flow rate, while limiting the circulation ducts, it is known to take high-pressure exhaust gases from the engine exhaust manifold, to cool them at the same time. using a water exchanger called high pressure exhaust gas cooler, and reinject them into the intake manifold of the engine. It is also known to bypass this heat exchanger to warm up the engine faster at startup.

  In addition, to reinject clean and cold exhaust gases, it is known to remove low pressure exhaust gases after a particulate filter, to cool them with a water exchanger called a gas cooler. exhaust at low pressure, and reinject them upstream of the turbo-compressor that provides the charge air.

  Finally, it is known to use a common module for cooling the supercharging air and the recirculated exhaust gas, this module having a common outlet box for a more efficient mixing of the gases.

  The design of a cooling system including a charge air cooler, a recirculated low pressure exhaust gas cooler and a high pressure recirculated exhaust gas cooler poses many practical difficulties.

  First of all, in order to be able to reinject clean recirculated exhaust gases upstream of the turbo-compressor, it is necessary to collect these gases after the particulate filter, which is placed in the exhaust channel under the vehicle.

  If the recirculated low-pressure exhaust gas cooler is placed near the particulate filter, this cooler must be supplied with cold water, which requires a large length of duct creating pressure losses and significant heating. . In addition, fresh gases must be brought in, which will also tend to warm up near the exhaust duct. Finally, to have enough flow in the return recirculated exhaust gas duct, it is necessary to place a counter-pressure valve after the quilting on the exhaust, which generates an additional cost and a strong counter-pressure in the exhaust pipe. exhaust manifold, and therefore a consumption of the engine.

  If the recirculated low-pressure exhaust gas cooler is placed close to the engine, it is necessary to bring back hot gases with a low flow rate, which is very difficult in practice. As in the previous case, it is necessary to artificially create a pressure drop on the exhaust line using a valve to generate flow in the recirculated exhaust gas cooler at low pressure. This loss of load penalizes the exhaust back-pressure and therefore the engine performance, not to mention its cost.

  On the other hand, with the new standards of pedestrian impact, the height under hood is reduced, while the ground clearance must remain constant. As a result, it becomes very complex to place a charge air cooler in the engine intake manifold.

  Finally, to reduce the pressure losses in the air ducts, it is preferable to convey cold air rather than hot air.

  The charge air coolers remote from the output of the turbo-compressor, penalize the intake pressure.

  The invention aims to provide a cooling circuit of the type comprising a first cooler, a second cooler and a third cooler, as defined in introduction, which overcomes the aforementioned drawbacks.

  To this end, it proposes such a circuit in which the first cooler, the second cooler and the third cooler are grouped together in the same cooling module and have respective envelopes which house respective heat exchange bodies and which are mutually fixed. , in particular by brazing.

  By grouping the three chillers within the same module, thanks to their respective envelopes, a compact compact module is created which makes it possible to solve the problems mentioned above.

  Because the respective casings of the three chillers are mutually secured, for example by brazing, this simplifies the circulation of a cooling liquid, generally water, and reduces the number of circulation ducts of this fluid.

  Other features of the invention are indicated below.

  - The envelope of the first cooler comprises a main face against which are fixed by brazing the envelope of the second cooler and the envelope of the third cooler.

  - Said main face is of substantially rectangular shape, while the respective envelopes of the second cooler and the third cooler are substantially parallelepipedal shape and arranged parallel to each other.

  The shell of the first cooler is connected to an inlet box for the supercharging air to be cooled and to an outlet box for the cooled supercharging air, said outlet box having a lateral connection for receiving high pressure exhaust from the third cooler.

  The second cooler shell is connected to an inlet box for the low pressure exhaust gas to be cooled and to an outlet box for the cooled low pressure exhaust gas.

  A particulate filter is disposed between the inlet box and the casing to filter the low pressure exhaust gas prior to cooling in the second cooler. The third cooler shell is connected to an inlet box for the high pressure exhaust gas to be cooled and to an outlet box for the cooled high pressure exhaust gas.

  A connecting pipe connects the outlet box of the third cooler to the lateral connection of the outlet box of the first cooler to cause the cooled high-pressure exhaust gases from the third cooler to mix with the cooled supercharging air from of the first cooler. - The first cooler, the second cooler and the third cooler are cooled by the same coolant.

  - The coolant circulates in a single liquid circuit.

  - The coolant passes successively through the second cooler, the third cooler and the first cooler. The casing of the second cooler is provided with an inlet pipe for the cooling liquid and an outlet orifice; the envelope of the third cooler is provided with an inlet adapted to communicate with the outlet orifice of the second cooler and an outlet orifice; and the shell of the first cooler is provided with an inlet adapted to communicate with the outlet port of the third cooler and an outlet pipe for the coolant.

  - The heat exchange body of the first cooler consists of a stack of plates housed in the envelope, so that a coolant can circulate between the plates and that the charge air can circulate around the plates . - The heat exchange body of the second cooler is constituted by a bundle of tubes housed in the casing, so that the exhaust gas can circulate in the tubes and that the coolant can circulate around the tubes . - The heat exchange body of the third cooler consists of a bundle of tubes housed in the casing, so that the exhaust gas can circulate in the tubes and that the coolant can circulate around the tubes.

  In the detailed description which follows, made only by way of example, reference is made to the accompanying drawings, in which: FIG. 1 is a diagram of a cooling circuit of an internal combustion engine comprising a first cooler, a second cooler and a third cooler grouped together in the same ihodule according to the invention;

  FIG. 2 is a perspective view of a cooling module according to the invention; FIG. 3 is a front view of the cooling module of FIG. 2; FIG. 4 is a view of the right side of the module of FIG. 3; FIG. 5 is a view on the left side of the module of FIG. 3; FIG. 6 is a view from above of the module of FIG. 3; and

  FIG. 7 is an exploded perspective view of the module of FIG. 2 showing the circulation of the cooling fluid in the three coolers.

  Referring first to Figure 1 which shows a cooling circuit 10 associated with an internal combustion engine M of a motor vehicle. The engine M comprises a motor unit 12 provided with an intake manifold 14 and an exhaust manifold 16.

  An intake line 18 supplied with external air 25 is connected to the intake manifold 14, while an exhaust line 20 is connected to the exhaust manifold 16 for exhausting the exhaust gases to the outside.

  The air is compressed by a turbo-compressor consisting of a compressor 22 mounted on the intake line 18 and a turbine 24 mounted on the exhaust line 20. The compressed air, also called supercharging air 10 9 from the compressor 22, is cooled by a first cooler 26 also called charge air cooler 26 (abbreviated RAS). In the example, a three-way valve 28 mounted at the outlet of the compressor 22 distributes the charge air between the charge air cooler 26 and a bypass line 30. In a variant embodiment, not shown, the valve 28 and the bypass line 30 could be omitted, the charge air then being sent only to the charge air cooler 26.

  The exhaust gases from the turbine 24 pass successively through a catalytic converter 32 and a particulate filter 34, both mounted on the exhaust line 20. Between the catalytic converter 32 and the filter 34 is mounted a three-way valve 36 which allows to return a portion of the recirculated exhaust gas in the intake line 18 upstream of the compressor 22, via a line 37. In this last line, the recirculated exhaust gas at low pressure pass successively through a particulate filter 38 and a second cooler 40 which is a recirculated exhaust gas cooler at low pressure.

  On the other hand, another three-way valve 42 is mounted between the exhaust manifold 16 and the turbine 24 to recirculate a portion of the exhaust gas, namely the high-pressure exhaust gas, in the exhaust line. intake 18 downstream of the cooler 26. These gases flow through a line 44 on which is installed a third cooler 46 which is a cooler for the exhaust gas recirculated at high pressure.

  The general architecture of circuit 10 of FIG. 1 is in itself known. It comprises three coolers, namely the cooler 26 for the charge air and the coolers 40 and 46 for the recirculated exhaust gas. These three chillers are usually cooled by water.

  The invention provides for grouping these three chillers 26, 40 and 46 in the same cooling module 48 as shown schematically by dashed lines. The particle filter 38 is, in the example, also grouped in the module 48. However, it could, in a variant, not be part of the module 48.

  Reference will now be made to FIGS. 2 to 6 to describe an exemplary embodiment of such a cooling module 48.

  The charge air cooler 26 comprises a casing 50 of generally parallelepipedal shape housing a heat exchange body 52 (visible in part 25 in FIG. 6) and connected to an inlet box 54 for the charge air. to cool (arrow F1) and an output box 56 for cooled charge air (arrow F2).

  The inlet box 54 is provided with an inlet pipe 58, while the outlet box 56 is provided with an outlet pipe 60 and further with a lateral connection 62 for receiving exhaust gases. at high pressure from the third cooler 46, as will be seen later. The envelope 50 comprises a main face 64 against which are fixed by soldering the envelope 66 of the cooler 40 and the envelope 68 of the cooler 46.

  The main face 64 of the cooler 26 is substantially rectangular in shape, and the respective envelopes 66 and 68 of the coolers 40 and 46 are of substantially parallelepipedal shape and arranged parallel to one another. The envelopes 66 and 68 have main faces (not visible in the drawings) of generally rectangular shape, which come into contact with the main face 64, the meeting of these two faces substantially corresponding to the whole of the main face 64.

  The envelope 66 of the second cooler 40 is connected to an inlet box 70 for the low-pressure exhaust gas to be cooled (arrow F3) and an outlet box 72 for the low-pressure exhaust gas. cooled (arrow F4). The boxes 70 and 72 are located respectively on the left and right sides of the module in FIG. 2. The particulate filter 38 is disposed between the inlet box 70 and the casing 66 to filter the exhaust gases at low pressure prior to cooling in the second cooler 40. The particulate filter 38 is dedicated to the recirculated exhaust gas at low pressure. In the example, the particle filter 38 is part of the module, but it might not be part of it.

  The filter is removably mounted by means of a flange or the like for replacement.

  A main filter 34 is however maintained. The backpressure created by the latter in the exhaust line 20 will contribute to maintaining a high flow rate in the cooler 40 at low pressure of the module and this without the addition of a back pressure valve.

  The envelope 68 of the third cooler is connected to an inlet box 74 for the high-pressure recirculated exhaust gas to be cooled (arrow F5) and to an outlet box 76 for the cooled high-pressure exhaust gas ( arrow F6).

  The input box 74 and the output box 76 are situated respectively on the right side and on the left side of the module if we consider FIG. 2. An angled connecting duct 78 connects the outlet box 76 of the third cooler. 46 to the lateral connection 62 of the outlet box 56 of the cooler 26 to cause the high-pressure exhaust gas, once cooled, to mix with the cooled charge air from the cooler 26.

  In the example shown, the heat exchange body 52 of the first cooler 26 consists of a stack of plates 80 (FIG. 7) housed in the envelope 50 so that a coolant can circulate between the plates. and that charge air can circulate around the plates. Corrugated inserts 82 (Fig. 7) are located around the plates to facilitate the exchange of heat between the charge air and the coolant.

  The casing 66 of the second cooler 40 houses a heat exchange body 84 (see FIG. 4) which consists of a bundle of tubes so that the exhaust gases can circulate in the tubes and the coolant can circulate around the tubes.

  Similarly, the envelope 68 of the third cooler 46 houses a heat exchange body 86 (see FIG. 4) consisting of a bundle of tubes, so that the exhaust gases can circulate in the tubes and the coolant can circulate around the tubes.

  In the example shown, the same cooling liquid, advantageously water with an antifreeze, successively passes through the second cooler 40, the third cooler 46 and the first cooler 26. The circulation of the coolant will now be made in reference to Figure 7.

  The casing 66 of the second cooler 40 is provided with an inlet pipe 88 for the coolant, which is located close to the outlet box 72. The coolant then circulates in the casing, against the flow relative to the direction of flow of the recirculated exhaust gas, and leaves the casing through an outlet port 90 disposed near the particle filter 38. This outlet port 90 is arranged in a side face of the casing 66 which is opposite an adjacent side face of the envelope 68 of the third cooler 46.

  The envelope 68 is provided with an inlet orifice 92 (FIG. 7) able to communicate with the aforementioned outlet orifice 90. The coolant then circulates inside the casing 68 against the current relative to the direction of circulation of the recirculated exhaust gas and leaves the casing through an outlet orifice 94 formed in one face of the casing 68 located vis-à-vis the main face 64 of the casing 50 of the first cooler 26.

  The envelope 50 is provided with an inlet orifice (FIG. 7) capable of communicating with the aforementioned outlet orifice 94 and an outlet pipe 98 for the cooling liquid which is situated on a second main face 100 the envelope 50, opposite the main face 64. The circulation of the coolant in the three coolers is shown schematically by the arrows in Figure 7. As the respective envelopes of the three coolers are adjacent and they communicate two to two for the circulation of coolant, this circuit is optimized which reduces the length of the connecting ducts and, therefore, potential risks of leakage.

  The three coolers in the module form a single component that can be brazed at one time. A flange makes it easy to attach the particulate filter 38 to the module for mounting or replacement. The invention is not limited to the embodiment described above and other variants are conceivable within the scope of the invention.

  In a second embodiment (not shown), the cooler 46 for the high-pressure exhaust gas may be plate-mounted and mounted under the charge air cooler 26 and be supplied in parallel with the coolant of the engine. cooler 26 or independently with a liquid for cooling the motor M by means of a stitching on the engine block 12.

  The charge air cooler 26 can also be plates, which allows to have a complete plate module formed by the cooler 26 and the cooler 46.

  In this case, the cooler 40 of the low-pressure gases may consist of tubes placed at 90 with respect to the stacking direction of the plates of the cooler 26 in order to place a maximum of tubes in the depth. The supply valve 42 (FIG. 1) of the high-pressure cooler 46 can then be directly mounted at the outlet of the exhaust manifold.

  In a third embodiment (not shown), in the case where the supply circuit of the cooler 46 of the high-pressure exhaust gas is independent, and / or to reduce the thickness of the module, it is possible to place this cooler 46 under the particulate filter 38. It is then preferred a tube cooler configuration to take advantage of the thickness of the 16 charge air cooler. The outlet box 56 remains common to the cooler 26 and the cooler 46 to ensure good mixing of the gases.

  The aforementioned three coolers module may consist of plates or tubes and have disrupters on the air or gas and / or water.

  The charge air cooler 26 may be bypassed or not as needed.

  The valve 28 and the bypass duct 30 (Figure 1) may be optionally integrated in the module.

  The cooling of each cooler can be performed by the same liquid circuit as shown in the previous example or by separate circuits.

  For common cooling of the module, the liquid used may be cooled by an independent low-temperature radiator or a part or all of a high-temperature radiator.

  For separate cooling, the installation of the high pressure cooler on the crankcase allows a supply of the latter by the engine coolant through a simple tapping on the water circuit of the crankcase.

  To cool the exhaust gas cooler (s), it is also possible to use the coolant of the turbo-compressor if it is cooled by such a liquid. In fact, the liquid circuit use pads 17 for the turbo-compressor and the exhaust gas coolers are not superimposed and this limits the length of the water pipes. The invention is particularly applicable to motor vehicles.

Claims (15)

claims   A cooling circuit for an internal combustion engine, of the type comprising a first cooler (26) which is a charge air cooler, a second cooler (40) which is a low pressure recirculated exhaust gas cooler and a third cooler (46) which is a high pressure recirculated exhaust gas cooler, characterized in that the first cooler (26), the second cooler (40) and the third cooler (46) are combined in a single cooling module (48) and have respective shells (50; 66; 68) which house respective heat exchange bodies (52; 84; 86) and which are mutually secured, in particular by brazing.   2. Cooling circuit according to claim 1, characterized in that the casing (50) of the first cooler (26) comprises a main face (64) against which are fixed by soldering the envelope (66) of the second cooler (40). ) and the envelope (68) of the third cooler (46).   3. Cooling circuit according to claim 2, characterized in that said main face (64) is of substantially rectangular shape, and in that the respective envelopes (66, 68) of the second cooler (40) and the third cooler (46). ) are of substantially parallelepipedal shape and arranged parallel to each other. 18   Cooling system according to one of claims 1 to 3, characterized in that the casing (50) of the first cooler (26) is connected to an inlet box (54) for the charge air to be cooled. and an outlet box (56) for the cooled charge air, said outlet box (56) having a side connection (62) for receiving high pressure exhaust gas from the third cooler (46).   Cooling system according to one of Claims 1 to 4, characterized in that the casing (66) of the second cooler (40) is connected to an inlet box (70) for the low-temperature exhaust gases. pressure to be cooled and an outlet box (72) for cooled low pressure exhaust gas.   Cooling system according to claim 5, characterized in that a particulate filter (38) is arranged between the inlet box (70) and the casing (66) for filtering the low pressure exhaust gas. before being cooled in the second cooler (40).   Cooling system according to one of Claims 1 to 6, characterized in that the casing (68) of the third cooler (46) is connected to an inlet box (74) for the high-pressure exhaust gases. pressure to be cooled and an outlet box (76) for the cooled high pressure exhaust gas.   8. Cooling circuit according to claim 7, taken in combination with claim 4, characterized in that a connecting pipe (78) connects the outlet box (76) of the third cooler (46) to the lateral connection (62). the outlet box (56) of the first cooler (26) for causing the cooled high pressure exhaust gas from the third cooler (46) to mix with the cooled charge air from the first cooler (26).   9. Cooling circuit according to one of claims 1 to 8, characterized in that the first cooler (26), the second cooler (40) and the third cooler (46) are cooled by the same coolant.   Cooling circuit according to claim 9, characterized in that the coolant circulates in a single liquid circuit.   11. Cooling circuit according to one of claims 9 and 10, characterized in that the coolant passes successively through the second cooler (40), the third cooler (46) and the first cooler (26).   Cooling system according to claim 11, characterized in that the casing (66) of the second cooler (40) is provided with an inlet pipe (88) for the coolant and a coolant port. output (90); in that the envelope (68) of the third cooler (46) is provided with an inlet (92) adapted to communicate with the outlet (90) of the second cooler (40) and a outlet port (94); and in that the shell (50) of the first cooler (26) is provided with an inlet port adapted to communicate with the outlet (94) of the third cooler (48) and an outlet pipe ( 98) for the coolant.   Cooling circuit according to one of claims 1 to 12, characterized in that the heat exchange body (52) of the first cooler (26) consists of a stack of plates (80) housed in the envelope (50), so that coolant can circulate between the plates and the charge air can circulate around the plates.   Cooling circuit according to one of claims 1 to 13, characterized in that the heat exchange body (84) of the second cooler (40) consists of a bundle of tubes housed in the casing (66). ), so that the exhaust gases can circulate in the tubes and that the coolant can circulate around the tubes.   Cooling circuit according to one of claims 1 to 14, characterized in that the heat exchange body (86) of the third cooler (46) consists of a bundle of tubes housed in the casing (68). ), so that the exhaust gases can circulate in the tubes and that the coolant can circulate around the tubes.