Abstract:
The present invention is a device for controlling a quantity of air introduced into an inlet of a boosted internal combustion engine with the engine having exhaust gas outlets each connected to an exhaust manifold of at least one cylinder. The device includes a boosting device comprising a turbocharger having a turbine with intakes connected to the exhaust gas outlets, an external-air compressor and a duct for partially transferring the compressed air from the compressor to the intakes. The partial transfer duct has branches connected to the turbine intakes which each have valve regulation for controlling circulation of compressed air in the branches.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    Reference is made to International Application No. PCT/EP2015/064282 filed Jun. 24, 2015 and French Application No. 14/57,141 filed Jul. 24, 2014, which are hereby incorporated herein by reference in their entirety. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    Field of the Invention 
         [0003]    This invention relates to a device for controlling the quantity of air introduced into the inlet of a boosted internal combustion engine, particularly a stationary engine or one for a motor vehicle or commercial vehicle and a method of controlling the quantity of air for such an engine. 
         [0004]    Description of the Prior Art 
         [0005]    As is widely known, the power delivered by an internal combustion engine is dependent on the quantity of air introduced into the engine&#39;s combustion chamber which is proportional to the density of this air. 
         [0006]    Therefore, it is customary to increase this quantity of air by compressing external air before it is let into this combustion chamber. This operation, which is called boosting, can be carried out by any means, such as a turbocharger or a mechanically driven compressor, which may be centrifugal or of the positive-displacement type. 
         [0007]    In the case of boosting by a turbocharger, the latter comprises a single flow or double flow rotary turbine, connected by a shaft to a rotary compressor. The exhaust gases coming from the engine pass through the turbine which is then rotatingly driven. This rotation is then transmitted to the compressor which, by its very rotation, compresses the external air before it is introduced into the combustion chamber. 
         [0008]    As is better described in French patent application 2 478 736, in order to significantly increase this quantity of compressed air in the engine combustion chamber, it is intended to increase the compression of external air by the compressor further still. 
         [0009]    This is effected more particularly by increasing the speed of rotation of the turbine and therefore of the compressor. 
         [0010]    For this, a portion of the compressed air coming out of the compressor is diverted to be let directly into the turbine intake to mix with the exhaust gases. This turbine is then crossed by a greater quantity of fluid (a mixture of compressed air and exhaust gas), whereby the speed of rotation of the turbine and consequently of the compressor can be increased. Therefore, with this compressor speed increase, it is possible to increase the pressure of the external air which will be compressed in this compressor and then introduced into the engine combustion chamber. 
         [0011]    Due to this, the compressed air is of a higher density whereby the quantity of air contained by the combustion chamber can be increased. 
         [0012]    This type of boosted engine, although satisfactory, nevertheless has some significant drawbacks. 
         [0013]    In fact, if the flow rate of the compressed air which is let into the turbine intake is not correctly controlled, this may lead to an engine malfunction. 
         [0014]    Therefore, by way of example, in the event of too great a quantity of compressed air being diverted to the turbine intake, the exhaust gases entering the turbine are cooled too much by this air and bring about a reduction in the overall performance of the boosting. 
       SUMMARY OF THE INVENTION 
       [0015]    The present invention rectifies the aforementioned drawbacks by means of a device for controlling the quantity of air introduced into the intake of a boosted internal combustion engine with which it is possible to respond to all the engine&#39;s power requirements. 
         [0016]    With the invention it is also possible to carry out a transfer of compressed air from the inlet to the exhaust even when the mean pressure of the compressed air in the inlet is lower than that of the gases in the exhaust. It is simply sufficient that there are phases during the engine operation cycle where the pressure in the inlet is higher than that in the exhaust. 
         [0017]    To this end, the present invention is to a device for controlling the quantity of air introduced into the inlet of a boosted internal combustion engine. The engine comprises two exhaust gas outlets with outlet being each connected to an exhaust manifold of at least one cylinder. The invention comprises a boosting device with a turbocharger comprising a double intake turbine connected to the exhaust gas outlets as well as an external-air compressor and a duct for partial transfer of the compressed air from the compressor to the turbine intakes wherein the partial transfer duct comprises two branches connected to the turbine intakes which each carry a valve regulator controlling the circulation of the compressed air in these branches. 
         [0018]    Advantageously, the branches can each also carry a non-return valve. 
         [0019]    One of the branches can be connected to the other branch with a connecting line. 
         [0020]    The connecting line can carry valve regulation. 
         [0021]    The valve regulation can comprise proportional valves. 
         [0022]    The transfer duct can carry heating for the compressed air circulating therein. 
         [0023]    The heating can comprise a heat exchanger. 
         [0024]    The heat exchanger can comprise an intake for exhaust gas coming from the turbocharger turbine and an exhaust gas outlet to the exhaust line. 
         [0025]    The invention also relates to a method of controlling the quantity of compressed air in the inlet of a boosted internal combustion engine. The engine comprises two exhaust gas outlets with each outlet being connected to an exhaust manifold of a at least one cylinder. The invention comprises a boosting device with a turbocharger with a double intake turbine connected to the exhaust gas outlets as well as an external-air compressor and a duct for partial transfer of the compressed air from the compressor to the turbine intakes, wherein a portion of the compressed air is introduced from the compressor into the turbine&#39;s exhaust gas intake sections. 
         [0026]    The method can divide the transfer duct into two branches and can controlling the circulation of the compressed air in each of the branches with valve regulation means. 
         [0027]    The method can connecting one of the branches to the other branch with a connecting line. 
         [0028]    The method can consist of heating the compressed air circulating in the transfer duct before intake into the turbine. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0029]    The other features and benefits of the invention will appear from reading the description which is to follow, given for solely illustrative purposes and on a non-limiting basis and to which the following are attached: 
           [0030]      FIG. 1  illustrates an internal combustion engine with a boosting device according to the invention; 
           [0031]      FIG. 2  shows a variant of the internal combustion engine with its boosting device and 
           [0032]      FIG. 3  illustrates a variant of the internal combustion engine with its boosting device according to  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0033]    In  FIG. 1 , the internal combustion engine  10  comprises at least two cylinders, which here are four cylinders referenced  12   1  to  12   4  from the left of the figure. 
         [0034]    Preferably, this engine is a direct injection internal combustion engine, particularly of the Diesel type but this in no way excludes any other type of internal combustion engine. 
         [0035]    Each cylinder comprises an inlet means  14  or inlet with at least one inlet valve  16 . Here two inlet valves each controlling an induction pipe  18 . The induction pipes  18  end at an inlet manifold  20  supplied by a supply duct  22  with inlet air, such as compressed air. 
         [0036]    This cylinder also comprises burned gas exhaust means  24  or exhaust with at least one exhaust valve  26 . Here two valves, control an exhaust tube or lines  28 . 
         [0037]    In the example illustrated, the engine is prepared for operating with a firing order of 1-3-4-2. In view of this firing order, the exhaust tubes or lines of the first cylinder  12   1  and second cylinder  12   4 , which form a first unit of at least one cylinder, are connected to a first exhaust manifold  30  with a first exhaust gas outlet  32 . The exhaust tubes or lines of the third and fourth cylinders  12   2  and  12   3 , which form a second unit of at least one cylinder, are connected to a second exhaust manifold  34  which comprises a second exhaust gas outlet  36 . 
         [0038]    The two exhaust gas outlets lead to a turbocharger  38  for compressing air and more particularly to the expansion turbine  40  of this turbocharger. 
         [0039]    As illustrated in  FIG. 1 , the turbocharger is a double intake turbocharger, better known by the term “Twin Scroll” turbocharger. 
         [0040]    This type of turbocharger comprises the expansion turbine  40  which is swept by the exhaust gases and rotatingly connected, by a shaft  42 , to a compressor  44 . 
         [0041]    At the turbine, the exhaust gas intake is divided into two sections. A first intake section  46  is connected to the first exhaust gas outlet  32  of the first manifold  30  and a second intake section  48  is connected to the second exhaust gas outlet  36  of the second exhaust manifold  34 . 
         [0042]    The gas discharge  50  of the turbine  40  is conventionally connected to the engine&#39;s exhaust line  52 . 
         [0043]    The compressor  44  of the turbocharger  38  comprises an external-air inlet  54  supplied by a supply duct  56 . This compressor&#39;s compressed air outlet  58  is connected to the supply duct  22  of the inlet manifold  20  by a duct  60 . 
         [0044]    Advantageously, it can be arranged to place a compressed air cooler  62  on the duct  60 , between the compressor and the duct  22 . 
         [0045]    As can be seen better in  FIG. 1 , with a transfer duct  64 , a portion of the compressed air coming out of the compressor  44  can be made to circulate to the turbine intakes  46  and  48 . 
         [0046]    More precisely, this partial transfer duct starts in the duct  60 , at an intersection point  66  between the compressor and the cooler  62  and is then divided, from a bifurcation point  68 , into two branches  70  and  72 . The branch  70  leads to the turbine intake  46  via its connection to the first exhaust gas outlet  32  and the branch  72  leads to this turbine&#39;s other intake  48  via its connection to the exhaust gas outlet  36 . 
         [0047]    Each branch carries valve regulation means of regulation  74  and  76 , such as a proportional valve, controlled by a control means  78 , which can be common to the two valve regulation means. Therefore, with this valve, the circulation of the compressed air in the branch can be controlled. 
         [0048]    Advantageously, each branch also comprises a non-return valve  80  and  82  which prevents the circulation of the compressed air from the branch to the compressor, while preventing the two branches from coming into communication. 
         [0049]    Therefore, with this configuration, it is possible during operation of the engine to take advantage of the zones of low exhaust pressure prevailing intermittently in the exhaust manifolds to introduce compressed air into the turbine and thus to increase the flow rate of this turbine and consequently of the compressor. With this, it is also possible to have more efficient boosting for low engine speeds. 
         [0050]    During operation, in case of a requirement for air in a large quantity in the cylinders, the valves  74  and  76  are made to open to introduce compressed air from the compressor  44  into the turbine  40 . 
         [0051]    The compressed air coming from the compressor  44  circulates in the duct  64  and then in the branches  70  and  72  to reach the exhaust gas intakes  46  and  48  of the turbine  40 , delivering surplus fluid to this turbine. 
         [0052]    Therefore, the turbine is swept not only by the exhaust gases from the outlets  32  and  36  but also by compressed air which is added to these gases. Because of this, turbine rotation is increased, which causes an increase in compressor rotation and consequently an increase in the pressure of the compressed air which comes from this compressor. 
         [0053]    Of course, the valves  74  and  76  are controlled by the control means or control  78  so as to let into the turbine the quantity of compressed air which meets the engine&#39;s boosting requirements. 
         [0054]    The variant in  FIG. 2  can be distinguished from  FIG. 1  due to the placing of a connecting duct  84  between the two branches  70  and  72 . This duct is provided with a regulation valve means or regulation  86 , such as a proportional valve which, here, is also controlled by the control means or control  78 . 
         [0055]    One of the ends of this duct is connected to the branch  70  at a point situated between the valve  74  and the exhaust gas outlet  32  and the other end is connected at a point situated between the valve  76  and the exhaust gas outlet  36 . 
         [0056]    With this duct, it is possible to control the communication of fluid between the two branches reaching the turbine. 
         [0057]    More precisely, with this connecting duct, it is possible to divert a portion of the compressed air circulating in one of the branches to introduce it into the other branch, mixing with the exhaust gases at the intakes of the turbine  40 . 
         [0058]    Furthermore, with the connecting duct, it is possible to restore in one branch of the turbine the pressure differential of the exhaust gases (or pulsating exhaust) of the other branch which is angularly offset in the engine combustion cycle. 
         [0059]    In  FIG. 3 , which essentially comprises the same elements as those in  FIG. 1 , the compressed air leaving the compressor  44  and circulating in the transfer duct  64  is heated before being introduced into the turbine  40 . 
         [0060]    For this purpose, the transfer duct  64  carries a means of heater  88  for heating the compressed air, which here is a heat exchanger in the form of a heat radiator, placed between the intersection point  66  and the bifurcation point  68  of the duct. This radiator is crossed by the compressed air which circulates in this duct while being swept by the engine exhaust gases. These exhaust gases come from the turbine discharge  50  and are conveyed by a duct  90  to the radiator intake  92 . The exhaust gases sweep this radiator, transferring the heat they contain to the compressed air, subsequently to leave this radiator again through the outlet  94 , to be directed to the engine exhaust line. 
         [0061]    Therefore, a portion of the exhaust gas energy is recovered by the compressed air which is introduced into the turbine through one or other of the intakes  46  and  48 . 
         [0062]    Therefore, with this heated compressed air, it is possible to supply extra energy to the turbine which, as a result, will rotate at a higher speed. This high speed of rotation is then transmitted to the compressor, which will carry out higher compression of external air.