FR3079880A1 - DUAL FLOW ADMISSION MODULE - Google Patents

Abstract

The invention relates to a heat engine (10) comprising a high-pressure recirculated gas cooling stage (24) and a precooling stage (20) of mixed fresh air compressed with a small footprint; the two stages are housed inside a cooling casing (27) in which engine coolant circulates.

Description

HEAT ENGINE DUAL FLOW INTAKE MODULE

Technical field of the invention

The present invention relates to a heat engine of a motor vehicle.

The present invention also relates to an air and gas intake module of a heat engine.

The present invention relates more particularly to an air and burnt gas intake module with an optimized cooling system.

State of the art

In known manner, a heat engine can include a supercharging system in order to increase the performance of said engine. The supercharging system includes an air compression stage before it enters the engine to be mixed with fuel. This compression stage can be associated with a turbine stage to form together a turbocharger or be an electrical compression module. The compressed air is then sent to an engine combustion chamber. However, the air temperature is increased following compression and the density of the compressed air introduced into the combustion chamber is then which also reduces the efficiency of the engine.

It is known to pass the compressed air after the compression stage and upstream of the engine in a cooling stage commonly called "precooler" which is formed by an air-water exchanger. In said exchanger, the air circulates in contact with fins around tubes in which circulates cooling water coming from an engine cooling circuit. Such a cooling circuit can for example pass through the engine to cool parts brought to high temperature of the engine such as the cylinder blocks and the cylinder head, the cooling water then being loaded with calories, and then by a radiator to allow removal. said calories and their removal. The cooling water is circulated using a water pump generally driven by the engine.

To reduce the discharge of pollutants generated by combustion, it is known to bring burnt gases to the exhaust, that is to say downstream of combustion in the cylinders, towards the intake ducts. Said gases are called recirculated gases. There are thus different types of recirculated burnt gases:

-high pressure recirculated gases taken from the upstream exhaust circuit in the direction of flow of the gases from pollution control devices such as a catalyst or a nitrogen oxide (Nox) trap. In general, the high pressure recirculated burnt gases are taken directly from an exhaust manifold fixed to an exhaust face of the cylinder head, on the lateral side opposite to the intake face. The high pressure recirculated gases are then sent to the intake ducts or to the intake manifold. In known manner, according to different operating phases of the engine, the high-pressure recirculated gases may or may not pass through a pre-cooling module disposed upstream of the intake in said intake ducts according to the direction of circulation of the gases of the 'admission. To do this, a bypass flap is arranged upstream of said precooling module to bypass said precooling module, especially during the operating phases with a cold engine. Then, said bypass flap can therefore be brought to high temperature and it should be cooled to keep its functional efficiency.

The invention described below relates to the cooling of high pressure recirculated gases upstream of the intake into the engine in a cooling module to increase the cooling of said recirculated gases.

- low pressure recirculated burnt gases taken from the exhaust circuit and in a known manner after a pollution control device. Said low-pressure recirculated gases are returned in a known manner to the intake circuit upstream of the compressor. They are then mixed with the fresh air captured on the front of the vehicle. However after compression, the air mixture with recirculated intake gases has warmed which is detrimental to the efficiency of the engine.

To reduce the temperature of the mixture before its admission into the engine, a heat exchanger such as a WCAC acronym for "Water cooled Charge Air Coder" in English or water-air cooling module, is arranged in the intake circuit of air, between the compression element and the engine intake manifold, to cool the compressed air that enters the combustion chambers. The cooling by said WCAC heat exchanger represents the main cooling module for the intake air but it may not be optimal.

The invention described below also relates to a stage for precooling the compressed mixture of intake air with low pressure recirculated gases upstream of the water-gas exchanger to increase the cooling of the compressed intake air. Said intake air can be the mixture of low-pressure recirculated gases with captured fresh air.

Publication EP1966476-B1 thus proposes a cooling module for high pressure recirculated gases which can be a WCAC. The temperature of the recirculated gases can be further elevated before entering the engine intake circuit, which reduces the efficiency of said engine.

In addition, additional cooling on the one hand of the recirculated gases upstream of the WCAC and on the other hand of the compressed air results in a consequent increase in the size of the powertrain comprising the engine and the various accessories necessary for its operation in the engine compartment, said engine compartment to be reduced for reasons of vehicle aesthetics.

The object of the invention presented here is an internal combustion engine with an optimized cooling circuit of said fresh and recirculated intake gases before they enter the intake circuit of the engine.

Presentation of the invention

The present invention relates more particularly to a heat engine of a motor vehicle comprising:

-a cylinder block,

-a cylinder head fixed above the cylinder block

-an air intake circuit comprising:

-a fresh air cooling stage arranged downstream of a compressor,

-a cooling stage for high pressure recirculated gases taken from an exhaust manifold fixed to the cylinder head,

Characterized in that the engine comprises a cooling casing in which circulates coolant capable of accommodating said two stages.

Advantageously, the internal combustion or internal combustion engine comprises a cooling casing in which are housed a stage for cooling compressed fresh air from a phase of compression by a compressor and a stage for cooling recirculated gases taken from a exhaust manifold fixed to the cylinder head, the two cooling stages being connected to the same engine air intake circuit and following the same operating rules. More simply, the two cooling stages must operate at the same time and stop at the same time. The cooling casing therefore makes it possible to significantly reduce the size of the powertrain comprising the engine and the elements necessary for its operation in a list comprising the coolers or heat exchangers.

According to other characteristics of the invention:

-the recirculated gas cooling stage includes a bypass or bypass flap which is housed in the cooling casing.

In known manner, the engine comprises a recirculation circuit of high pressure burnt gases taken from an exhaust manifold fixed to the cylinder head of the engine; said being at high temperatures at the exhaust and must therefore be cooled here by the cooling stage of the recirculated gases. However, during cold starts of the engine, it is necessary to quickly raise the temperature of said engine. A bypass duct is used to bypass the cooling stage to bring the burnt gases directly to the intake ducts or more commonly to the engine intake. The passage of the burnt gases through the cooling stage or through the bypass duct is controlled by a so-called bypass flap which can be mounted at high temperatures which may affect the proper functioning of said flap. Advantageously, said bypass flap is also immersed in the casing to be cooled in order to improve its efficiency and reliability.

-the engine comprises a bypass duct of the cooling circuit for the recirculated gases arranged outside the casing.

Advantageously, the engine comprises a bypass duct arranged outside the cooling casing and connected on one side to the bypass flap and on the other side to the engine intake ducts. Said bypass duct is advantageously isolated from the gas cooling stages and in particular from the engine cooling circuit.

the casing comprises an inlet face for the gases and the compressed air facing the engine exhaust face and an opposite outlet face facing the engine intake face and a lateral fixing wall disposed between the inlet and outlet faces and fixed to a wall of the engine cylinder head.

Advantageously, the cooling casing is fixed to a wall of the cylinder head of the engine by a lateral fixing wall whose shape is substantially complementary to the wall of the cylinder head. This makes it easier to assemble said casing to the heat engine. Advantageously, the casing runs along the cylinder head fixing wall and also defines a conduit for supplying recirculated gases from the exhaust face of the cylinder head to the intake face, said conduit is also perfectly maintained with respect to the cylinder head engine.

-the housing comprises a first compressed air inlet pipe connected to the compressor by a direct intake duct and a second high pressure recirculated gas inlet pipe connected directly to the exhaust manifold, both arranged at one end of the cooling housing facing the exhaust side of the engine.

Advantageously, the casing comprises a first end facing the exhaust face of the cylinder head comprising pipes which are connected in a substantially direct manner to an exhaust manifold and to the fresh air compressor by means of ducts which are of reduced length. . The overall mass of the conduits is thus optimized.

the cooling casing comprises a first compressed air outlet pipe connected upstream of a heat exchanger and a second recirculated gas outlet pipe separate from the first pipe and connected with an air intake circuit of the engine downstream of the heat exchanger.

Advantageously, the cooling casing comprises a second end diametrically opposite the first end facing the intake face of the cylinder head also comprising two pipes which are connected one to air intake ducts downstream of a heat exchanger fixed to the cylinder head and covering a plenum with an air distributor, and the other to an inlet duct upstream of said heat exchanger. The lengths of the connection ducts between the cooling casing and the air intake ducts and the heat exchanger are then reduced and optimized to reduce the overall size. In addition, the gases leaving the cooling casing are at reduced temperatures, which allows the use of flexible and light materials to optimize the overall size and mass.

-the cooling case comprises a coolant inlet nozzle and a coolant outlet nozzle both connected with an engine cooling circuit.

Advantageously, the cooling casing comprises an inlet nozzle and an outlet nozzle which are connected to a cooling circuit of the engine. In this simple way, the engine coolant enters the cooling sump to take in maximum calories given off by the recirculated gases and the compressed air and then lose them at the conventional level of a radiator.

-the coolant inlet and outlet ends of the coolant are connected to the cooling circuit of the engine's cylinder blocks.

Advantageously, the coolant inlet and outlet ends of the cooling casing are connected to the cooling circuit of the engine cylinder block. In this advantageous manner, the control of the cooling of the cooling housing is similar to that of the cylinder block, in particular in the case of “split-cooling” or double cooling circuit, a first circuit of which relates to the specific cooling of the cylinder block and a second specific cooling of the cylinder head.

Brief description of the figures

Other characteristics and advantages of the invention will appear on reading the following description of particular embodiments of the invention given by way of nonlimiting examples and represented in the appended drawings, in which:

FIG. 1 is a schematic top view of an engine with a cooling circuit for the recirculated gases and the compressed air.

FIG. 2 is a schematic view of the cooling casing grouping together a stage for cooling the recirculated gases and a stage for cooling the compressed air.

Detailed description of the figures

In the following description, identical reference numerals designate identical parts or having similar functions.

The terms upstream / downstream refer to the direction of gas flow.

According to Figure 1, an internal combustion or internal combustion engine comprises a cylinder block (not shown) and a cylinder head 11 fixed to said cylinder block and above it. Intake air enters the engine 10 through the intake face 12 of the cylinder head 11. After combustion of the burnt gases are evacuated by the exhaust face 14 of the cylinder head diametrically opposite to the intake face 12 .

Said heat engine 10, here pressed turbocom, comprises a turbocharger 15 with a turbine 16 with an axis of rotation 17 coinciding with the axis of rotation of a compressor 18 of intake air. The burnt gases pass through the turbine 16 and drive it in rotation and therefore also a compression wheel of the compressor 18.

Other types of compressors, in particular an electric compressor, can be used in the context of the invention to compress the intake air before it enters the engine 10.

After passing through the compressor 18, the temperature of the intake air is appreciably high. The high temperature of the intake air reduces the efficiency of the engine. It is therefore known to cool the intake air with a water-air heat exchanger 19 or "WCAC" acronym for Water Charge Air Cooler. Said exchanger is fixed against an intake face 12 of the cylinder head 11 and may, as shown in FIG. 1, comprise an air intake distributor with its plenum (not shown) connected with air intake ducts dug in said cylinder head 11 and leading to combustion chambers, each of the chambers is delimited by a cylinder, a movable piston sliding in the cylinder and a bottom wall of the cylinder head.

To meet increasingly stringent anti-pollution standards, an additional cooling stage 20 is added to the so-called “fresh” air intake circuit upstream from the water-air heat exchanger 19. Said stage cooling is called "precooler" or pre-cooling.

Said air is said to be fresh because it is captured from outside the vehicle in general at the front of the vehicle.

To meet pollution control standards, burnt gases are re-injected at the intake. Said burnt gases are also called recirculated gases or EGRs. The acronym "EGR" stands for Exhaust Gas Recirculation for flue gas recirculation. There are two types of recirculated gases:

- low pressure recirculated gases taken from or downstream of a pollution control device 21 such as a catalyst. Said low pressure recirculated gases are then mixed with fresh air. The mixture of fresh air with low pressure recirculated gases then passes through the compressor 18 and the temperature of said mixture increases accordingly.

-high pressure recirculated gases taken directly from an exhaust manifold 22. The high pressure recirculated gases are at very high temperatures and need to be cooled before being re-admitted into air intake ducts.

The high pressure recirculated gases pass a high pressure recirculated gas recirculation circuit 23 which includes an additional cooling stage 24, before their introduction into the air intake ducts of the engine 10 downstream of the water heat exchanger. air WCAC 19.

However, during the cold start phases, it is necessary to have a rapid rise in temperature of the engine. Also it is known not to cool the cylinder block during cold starts to allow a faster rise in temperature of said cylinder block, the cylinder head 11 comprising exhaust gas exhaust pipes quickly reaches a high temperature level.

It is also known not to cool the high pressure recirculated gases during the same cold starts. The recirculation circuit 23 for the high pressure recirculated gases therefore comprises a bypass duct 25 for bypassing the cooling stage 24. A bypass flap 26 is disposed upstream of the bypass duct 25 to allow the passage of the high pressure recirculated gases either by the bypass conduit 25 or by the cooling stage 24. Said bypass flap 26 being in contact with the recirculated gases is also brought to high temperature which can adversely affect its operation.

The invention relates to the heat engine 10 comprising an additional cooling stage for high-pressure recirculated gases 24 and a cooling stage 20 for the fresh air mixed and compressed with a reduced bulk.

According to FIG. 1, the engine 10 comprises a cylinder block (not shown), a cylinder head 11 fixed to said cylinder block and above the latter and an air intake circuit 50 which comprises:

the fresh air cooling stage 20 arranged downstream of the compressor 18,

-the cooling stage 24 of high-pressure recirculated gases taken from the exhaust manifold 22.

Said cooling stages 20, 24 are grouped together and housed inside a cooling casing 27. Said cooling stages are formed for example by coils (not shown) in which circulate the recirculated gases and the fresh air and which are immersed in a volume of coolant. Said volume of liquid is contained in the cooling casing 27. Said casing 27 is substantially of parallelepipedal shape with a lateral fixing wall 28 comprised between an end face 29 of the gas inlet facing the exhaust face 14 of the cylinder head 11 and an outlet end face 30 facing the inlet face 12 of said cylinder head. The lateral wall for fixing the casing 27 is substantially complementary to a transverse wall for fixing the cylinder head 37.

According to one embodiment of the invention, the cooling housing is fixed against the transverse wall of the cylinder head.

According to FIG. 2, the cooling casing 27 therefore comprises a first inlet pipe 31 for the compressed fresh air and a second inlet pipe 32 for the high pressure recirculated gases. The inlet pipes are advantageously arranged at the end of the casing 27 facing the inlet end face 29 of the air and the burnt gases. The pipes can, according to one embodiment, open out from the gas inlet end face 29. As a result, the connection of said casing 27 with the compressor which is also disposed on the side of the exhaust face of the cylinder head 11 is reduced length. It is the same for the connection of said casing 27 with a nozzle in the exhaust manifold 22 to collect the burnt gases. The reductions in link lengths allow on the one hand to reduce the size of the engine with the air cooling circuit 50 and on the other to reduce the overall mass.

The cooling casing also comprises a first outlet pipe for compressed fresh air 33 and a second outlet pipe for the burnt gases disposed at the opposite end of the casing 27 facing the outlet end face 30 of the casing 27. According to one embodiment of the invention, the outlet pipes open from the outlet end face 30 of the casing 27. The connection between the outlet pipe 33 of fresh air and the WCAC heat exchanger 19 is of length scaled down. It is the same for the connection between the outlet pipe 34 of the burnt gases and the air intake distributor. Reductions in connection lengths allow on the one hand to reduce the size of the engine with the air cooling circuit 50 and on the other hand to reduce the overall mass.

According to a preferred embodiment, the cooling casing 27 is able to accommodate the bypass flap 26 to ensure cooling and avoid high temperatures of said flap. The bypass duct 25 connected to said flap 26 opens out from the cooling casing to the outside to join the outlet pipe 34 of the burnt gases upstream of the intake manifold.

The cooling casing 27 comprises a first coolant inlet nozzle and a second outlet nozzle 36 for said liquid, the two tips are connected to an engine cooling circuit (not shown). According to one embodiment, two holes are made in a wall of the engine to reach the ducts of the engine cooling circuit. In said holes are driven pipes connected with the inlet and outlet nozzles 35, 36 of the cooling casing 27.

Preferably, the holes are drilled in a wall of the cylinder block to reach conduits of the cooling circuit of the cylinder block. The coolant inlet and outlet fittings 35, 36 of the cooling casing 27 are connected to the cooling circuit of the engine crankcase. The cooling control by the two cooling stages 20,24 is analogous to the cooling of the cylinder block. Particularly for engines with double cooling separate from the cylinder head and the cylinder block or “split cooling”, during the cold engine start-up phases, the two cooling stages 20,24 can easily be avoided by controlling only the cooling of the cylinder block. The coolant does not circulate in the cylinder block to allow a faster rise in temperature of said cylinder block, does not also circulate in the cooling block 27, which allows to keep a sufficiently high temperature of the recirculated gases and fresh intake air before admission to the engine 10.

The objective is achieved: the heat engine 10 comprises an air intake circuit composed of an additional cooling stage for high-pressure recirculated gases 24 and a cooling stage 20 for the fresh air mixed and compressed with a space requirement reduced and a reduction in the overall mass of the whole. Said air intake circuit can also easily bypass / stop the two stages of cooling of high pressure recirculated gases and compressed fresh air.

The invention relates to the heat engine 10 comprising an additional cooling stage for high-pressure recirculated gases 24 and a cooling stage 20 for the fresh air mixed and compressed with a reduced bulk.

Claims (8)

1. Motor vehicle heat engine (10) comprising -a cylinder block, -a cylinder head (11) fixed above the cylinder block -an air intake circuit (50) comprising: a fresh air cooling stage (20) arranged downstream of a compressor (18), -a cooling stage (24) of high pressure recirculated gases taken from an exhaust manifold (37), Characterized in that the engine (10) comprises a cooling casing (27) in which coolant circulates, capable of accommodating said two cooling stages (20,24). 2. Heat engine (10) according to claim 1, characterized in that the cooling stage of the recirculated gases (24) comprises a bypass flap (26) which is housed in the cooling housing (27). 3. A thermal engine (10) according to claim 1 or 2, characterized in that the engine (10) comprises a bypass duct (25) of the cooling circuit of the recirculated gases (23) arranged outside the cooling casing (27). 4. Heat engine (10) according to any one of claims 1 to 3, characterized in that the casing (27) comprises an inlet face (29) of the gases and of the compressed air turned towards the face of engine exhaust (14) and a diametrically opposite outlet face (30) facing the engine inlet face (12) and a fixing side wall (28) disposed between the inlet and outlet faces and fixed to a wall of the engine cylinder head. 5. Heat engine (10) according to any one of claims 1 to 4, characterized in that the casing (27) comprises a first inlet manifold (31) of compressed air connected to the compressor (18) by a conduit direct intake and a second high pressure recirculated gas inlet pipe (32) connected directly to the exhaust manifold (37), the two pipes are arranged at one end of the cooling casing (27) facing the exhaust side (14) of the cylinder head. 6. Heat engine (10) according to any one of claims 1 to 5, characterized in that the cooling housing (27) comprises a first outlet pipe (33) of compressed air connected upstream of a heat exchanger heat (19) and a second outlet pipe (34) for recirculated gases separate from the first pipe (33) and connected with an engine air intake circuit downstream of the heat exchanger (19). 7. A heat engine (10) according to any one of claims 1 to 6, characterized in that the cooling housing (27) comprises an inlet nozzle (35) of coolant and an outlet nozzle (36) coolant, both connected with an engine cooling circuit. 8. A heat engine (10) according to claim 7, characterized in that the inlet and outlet nozzles (35, 36) of coolant from the cooling housing (27) are connected to the cooling circuit of the cylinder housing. of the motor.