DEVICE AND METHOD FOR MONITORING THE INTRODUCTION OF AIR AND EXHAUST GAS TO THE INTAKE OF AN INTERNAL COMBUSTION ENGINE

The present invention relates to architectures and to a control device of a device for introduction of the quantity of air to the intake of a supercharged internal combustion engine, in particular a stationary engine or for a motor vehicle or industrial.

In particular, the present invention is suitable for engines, particularly diesel engines, equipped with a circuit exhaust gas recirculation.

As is widely known, the power delivered by an internal combustion engine is dependent upon the amount of air fed to the combustion chamber of this engine, amount of air which is itself proportional to the density of this air.

Thus, it is common to increase this amount of air by means of compression outside air before it is discharged into the combustion chamber. This operation, called supercharging, may be accomplished by any means, such as a turbocharger or a compressor driven, which may be a centrifugal or positive displacement.

In the case of a supercharging by a turbocharger, the latter comprises a rotatable turbine, single-flow or dual-flow, connected by a shaft to a rotary compressor. The exhaust gas from the internal combustion engine pass through the turbine which is then driven in rotation. This rotation is then transmitted to the compressor which, through its rotation, compresses outside air before it is introduced into the combustion chamber.

As is more fully described in the French patent application no. 2,478 736, there is, to be able to amplify significantly the amount of compressed air into the combustion chamber of the engine, to further increase the compression of the fresh air through the compressor.

This is accomplished in particular by increasing the rotational speed of the turbine and thus the compressor.

For this, it is used a circuit fluid amplifier, said circuit boosting, whereby a portion of the compressed air leaving the compressor is diverted to be admitted directly to the inlet of the turbine by mixing with the exhaust gas. The turbine is then traversed by a greater amount of fluid (mixture of compressed air and exhaust gas), thereby increasing the speed of rotation of the turbine and consequently of the compressor. This increase in compressor speed thus increases the pressure of outside air which will be compressed in the compressor and then introduced into the combustion chamber of the engine.

By this, the compressed air has a higher density and hence increasing the amount of air in the combustion chamber.

This type of supercharged engine, although satisfactory, nevertheless has significant drawbacks.

In effect, the flow rate of the compressed air which is admitted to the turbine inlet of the propellant, which may result a dysfonctionnent engine.

Thus, for example, by too large amount of compressed air diverted to the turbine inlet, the exhaust gas entering the turbine are cooled too large this air and causes a decrease in the overall efficiency of the supercharger.

In addition, one of the major difficulties with the present concept of supercharging with the boost circuit is its compatibility with the exhaust gas recirculation. Indeed, most diesel engines are equipped with a recirculating exhaust gas, said EGR flow path for "recirculating Exhaust gas beam", to limit to the source NOx emissions.

The exhaust gas recirculation is made generally by an EGR circuit the HP (high pressure recirculating Exhaust gas beam) taking the exhaust gas upstream of the turbine to return the medium downstream of the compressor intake air. The flow of recirculated exhaust gas being exactly the reverse of that of the boost air derived therefrom, is a conflict between the two circuits with a cancellation effects. It is therefore necessary to define a loop architecture specific air for rendering the circuit boost and EGR flow path the HP-compatible.

Known is the document EP is 1,138 928 that describes an EGR circuit and a circuit separate the boost at all points, thereby imposes a construction and complex commands.

On the contrary, the present invention relates to optimized architecture of the air loop and recirculation of exhaust gas from the engine for using on a same engine "the HP EGR" or "boosting", while avoiding complexity is too high for the ducts and the respective commands.

Thus, the present invention relates to a device for monitoring the amount of air introduced to the intake of a supercharged internal combustion engine comprising a supercharging system comprising a turbocharger having a turbine connected to at least one exhaust gas outlet of said motor and a compressor outside air, a conduit for partial transfer of the compressed air from the compressor to the turbine inlet, and a flue gas recirculation duct between an exhaust gas outlet and a compressed air intake line, characterized in that said transfer conduit and said conduit partial flue gas recirculation have at least one common portion.

The device may include a valving system controlled on the partial transfer circuit of compressed air and on the EGR circuit to control the exhaust gas recirculation cooler, or to control the partial transfer of compressed air to the turbine (8).

The system may include at least one throttling valve on the circuit for the exhaust gas recirculation cooler and a valve on the partial transfer conduit.

The transfer conduit section can be connected either upstream, or downstream of a heat exchanger on the compressed air line.

The winnowing can include at least one three-way valve.

The transfer conduit may comprise a partial exchanger for the exhaust gas recirculation.

The present invention also provides a method of monitoring the amount of air supplied to the intake of a supercharged internal combustion engine comprising a supercharging system comprising a turbocharger having a turbine connected to at least one exhaust gas outlet of said motor and a compressor outside air, a conduit for partial transfer of the compressed air from the compressor to the turbine inlet, and a conduit for recirculating exhaust gas between an exhaust gas outlet and a compressed air intake line, characterized in that there is used a common portion of duct for said partial transfer conduit and said conduit for exhaust gas recirculation.

The driving of the valving system to either perform the exhaust gas recirculation, either the partial transfer of compressed air.

Other features and advantages of the invention will appear upon reading the description which will follow, given as only illustrative and not limiting, and to which are appended:

figure 1 - that illustrates an internal combustion engine with its supercharging device and the HP EGR flow path used according to the invention;

figure 2 - which shows a variant of the internal combustion engine according to the invention;

figures 3 - 4 and which illustrate other embodiments of the internal combustion engine according to the invention.

In Figure 1, the internal combustion engine 1 comprises at least two cylinders, here four cylinder 121 to 124 referenced from the left of Figure.

Preferentially, this engine is a direct injection internal combustion engine, in particular a diesel engine, and instead moves in any way any other type of internal combustion engine.

Each cylinder includes inlet means with at least one intake valve controls an intake pipe 2. The intake pipes terminate at an intake manifold 3 powered by a supply conduit 4 in intake air, such as compressed air.

Each cylinder also comprises means exhaust burned gas with at least one exhaust valve which controls an exhaust pipe 5 leading to an exhaust manifold 6.

The exhaust manifold 7 6 results in a turbocharger for compressing air and more particularly to the expansion turbine of said turbocharger 8.

As shown in Figure 1, the turbocharger is a turbocharger to single input.

The invention is not limited to a single turbocharger inlet, it is also applicable to the turbochargers double input called " charger comprising twin>>, or even to turbochargers to n input with n greater than or equal to 2.

The gas outlet 9 of the turbine 8 is connected conventionally to the exhaust line of the engine.

The compressor 10 of the turbocharger 7 has an outdoor air inlet 11 fed by a supply line. The compressed air outlet of the compressor is connected to the supply line 4 of the intake manifold 3 by a conduit 12. 13 Noted the junction point between the conduits 4 and 12.

Advantageously, it can be proposed to a cool compressed air 14 on the conduit 12, between the compressor 10 and the pipe 4.

As best seen in Figure 1, a transfer conduit 15 is capable of circulating a portion of the compressed air exiting the compressor 10 toward the turbine inlet 8.

More specifically, the transfer pipe partial originates on the conduit 12, to a point of intersection 16 between the compressor and the cooling heat exchanger 14, and then merges, from a bifurcation point 17, 18 on a branch. The leg 18 terminates at the turbine inlet by its junction point 19 with the exhaust gas outlet 6.

A conduit 21 connects the leg 18 to the intake duct 4. It passes preferentially by heat exchanger 22 suitable for cooling exhaust gas.

Valves 23 and 24, preferably proportional, equipping the conduits respectively 15 and 21.

The branch referenced 15 also includes a check valve 20 which prevents the circulation of fluids and/or temples 18 21 to the compressor 10.

This establishes, during engine operation, enjoy low pressure areas currently prevailing exhaust in the exhaust manifold for introducing compressed air into the turbine and thereby increase the flow rate of the turbine and thus the compressor. This also have a boost more efficient for low speeds and particularly to handle transient phases with control strategies suitable proportional valves.

During operation, as required in a large amount of air into the cylinders, the valve 23 is open for introducing compressed air from the compressor into the turbine 10 8, together the valve 24 is controlled in closing.

The compressed air flowing from the compressor 10 flows through duct 15 and into the leg 18 to arrive at the exhaust gas inlet of the turbine 8 by delivering excess fluid to the turbine.

Thus, the turbine is covered not only by the exhaust gas from the manifold 5, but also by compressed air which is added to the gas. Thus, the rotation of the turbine is increased, which leads to increase of rotation of the compressor and, consequently, an increase in the pressure of the compressed air exiting the compressor.

In this configuration, the compressed air pipe 15 does not pass through the heat exchanger 14, and free operation (the EGR) since the valve 24 is closed.

For operation with exhaust gas recirculation (EGR flow) in order to reduce combustion temperatures and thus NOx emissions, the valve 23 is closed and the valve 24 is opened. A portion of the exhaust gas is introduced into the intake duct 4 by the legs 18 and 21 after it passes through the exchanger 22. This operates when the mean pressure of the exhaust is greater than the average pressure of the inlet.

It should be noted that the valves 23 and 24 may be replaced by a valve 3 paths whose function will be equivalent to control the different streams.

In addition, it is clear that the valve 24 (referred to as EGR valve) can be placed upstream (fig. 1) or downstream (not shown) of the heat exchanger 22.

Thus, in the present invention, uses at least a portion of a duct communicating on one side with the inlet of the turbine 8 and the other with the compressed air inlet. This duct portion permits passage of exhaust gas when the EGR valve 24 is opened and the valve 23 is closed. Also, it allows the passage of compressed air when the valve 23 is opened and the EGR valve 24 is closed.

Thus, there is obtained an architecture optimized in terms of conduits.

The embodiment of Figure 2 differs from Figure 1 by placing a connecting line 15a between two connection points 17 and 25 with the conduit 21. This connecting line is provided with valve means 23, as a proportional valve, and a check valve 20.

In this embodiment, the compressed air boosting circuit passes through the heat exchanger 14 and then the exchanger 22 of EGR, the connecting duct 15a and the leg 18. One advantage is that air circulation circuit boosting the counter flow in the exchanger 22 of EGR can be cleaned and/or cleaning of the same.

Figures 3 and 4, which have substantially the same elements as those of Figure 1, disclosing variations of arrangement according to the invention, which use a throttling element 30 of spool type valve including a valve box, for performing the various functions of circulation, according to whether in EGR or in the boost. The skilled person will be able to choose suitable components.

More specifically, in Figure 3, a valve 30, for example of type 3 way ball valve, is interposed downstream of the heat exchanger the EGR 22 on the EGR pipe 21. The control of this valve 30 permits passage of exhaust gas to the air intake duct 4 compressed by the abutment 13. A conduit 15b, which connects the valve 30 to the branch 18, is then closed.

The other position of the valve 30 allows the passage of a portion of compressed air through the conduit 18 towards the branch 15b for " booster the>>the turbine 8. Thus, the air of " boosting>>has passed through the heat exchanger 14, without going through the exchanger cooler 22.

Alternatively, represented by the conduit 15c dotted lines in Figure 3, shows the valve 30 connected to the junction point 16 upstream of the heat exchanger 14 of the compressed air. The valve 30 is not here connected to the junction point 13. The boost air circuit is herein results in direct to the turbine 8. By contrast the exhaust gas from the EGR flow path passes through the exchangers 22 and 14 in joining the point of junction 16 of the compressed air line.

Figure 4 describes another embodiment wherein the valve 30 is connected to the junction point 13 for conducting fluids therethrough toward the compressed air intake duct 4. This three-way valve is supplied with air by a conduit the boost circuit connected to the junction point 16 upstream of the heat exchanger 14, and the EGR exhaust gas by the branch 18. Thus, the common duct for EGR " boosting>>comprises the leg 18 and the exchanger the EGR. Noted, as represented by the reference 22a, that the exchanger EGR can be placed downstream of the valve 30 before the junction point 13. A non-return valve 32 may be positioned downstream of the heat exchanger 14 to block the exhaust gas in the case of the EGR operation.

According to the invention described in example 1 to 4 of the drawings, at least a portion of the EGR pipe, generally integrated into the exhaust manifold but preemptible also in the cylinder head, is used to cause a portion of compressed air to the turbine inlet to provide a low " boosting>>.