FR2872550A1 - Water injecting device for e.g. spark ignition engine, has reservoir to collect water contained in exhaust gas for injection, and unique injecting device to inject mixture of water and fuel in combustion chamber of engine - Google Patents

Abstract

The device has a condenser (13) placed on an exhaust duct (12) of an engine and a reservoir (14) for collecting water contained in exhaust gas for injection. An emulsifier device (19) receives fuel and water from the reservoir, and forms a mixture of water and fuel. A unique injecting device (25) injects the mixture in a combustion chamber (3) of the engine. An independent claim is also included for a method of injecting water in a combustion chamber of an internal combustion engine of a motor vehicle.

Description

Device for injecting water into an internal combustion engine and

associated process

  The invention relates to the automotive field and more particularly to the operation of an internal combustion engine whether of the spark ignition type or the diesel type.

  Restrictions on the emission of exhaust pollutants from internal combustion engines of motor vehicles require the development of more and more effective abatement strategies.

  One of these strategies is to recirculate a portion of the exhaust gas from combustion using a partial exhaust gas recirculation (EOR) line. The reintroduction of the exhaust gases at the intake of the engine makes it possible to reduce the combustion temperature inside the cylinders and thus to define a compromise between the emission of the particles and the emission of nitrogen oxides. NOx.

  Another strategy that also makes it possible to reduce the temperature of the combustion in the cylinders and to limit the production of the NOx nitrogen oxides consists in injecting liquid water directly into the combustion chambers.

  European patent application EP-A-1 209 345 (FilterWerk Mann & Hummel) discloses a device for recovering the water in the fuel supplying the internal combustion engine. A filter placed on the fuel supply line allows the recovery of a certain amount of water which is then injected into the recirculation circuit of the exhaust gas or, alternatively, directly into the combustion chamber.

  In the French patent application FR-A-2,833,652 (Renault) the water removed from the fuel under the same conditions as in the previous document, is reinjected into the air duct at the intake of the internal combustion engine or in the exhaust pipe downstream of the engine. In this document, the purpose is essentially to remove the water in the fuel injected into the combustion chamber.

  It is also known to recover the water contained in the exhaust gases from combustion in the engine by cooling the exhaust gas and partial condensation. Thus, in the patent application WO-A-03/001046 (Alstom) the water recovered by condensation from the exhaust gas and stored in a tank, is then brought to an evaporator which vaporizes it. , the steam obtained being mixed with the air admitted into the engine.

  The patent application WO-A-01/92710 (Emitec) also provides for recovering water from the exhaust gases from the engine by condensation. The recovered water, stored in a tank, is used for direct injection into the engine to reduce emissions of CO2 and NOx nitrogen oxides.

  Given these different known devices, the object of the invention is to improve the depollution effect produced by the injection of water into the combustion chamber of a heat engine.

  The object of the invention is also to reduce the occurrence of rattling phenomena which frequently result from the introduction of water into the combustion chamber at uncontrolled times of the engine operating cycle.

  The invention also relates to an arrangement that allows an injection of water into the combustion chamber of the engine without increasing the dimensions of the combustion chamber or the cylinder head of the engine.

  The device, according to one aspect of the invention, for injecting water into a combustion chamber of an internal combustion engine, particularly for a motor vehicle, comprises a condenser mounted on the engine exhaust pipe and a reservoir for recover the water contained in the exhaust gases for injection. The device further comprises an emulsifier device receiving fuel and water from the aforementioned tank and capable of forming a mixture of water and fuel, and a device for injecting said mixture into the combustion chamber of the engine.

  Preferably, the injection device comprises a single injector for each combustion chamber. Thus, the structure of the assembly is simplified as well as the structure of the combustion chamber and the cylinder head of the engine since it is not necessary to provide separate injectors for fuel and water.

  In addition, the injection of water being made with the fuel, the injection occurs at the last moment in the cycle of the engine, thus improving the efficiency of the depollution of the exhaust gases and reducing the rattling phenomena.

  The recovery of the water contained in the exhaust gases by cooling and condensation avoids the need to provide a specific external water source for the injection.

  In addition, the tank can also be connected to a condenser device of an air-conditioning installation equipping the motor vehicle, thus increasing the quantity of water recovered during the operation of the vehicle and usable for injection into the combustion chamber of the engine. .

  In an advantageous embodiment, it is also possible to provide a means of regulating the amount of water supplied to the emulsifier device.

  The invention applies to any type of combustion engine, whether it is spark ignition or diesel type. The invention also applies to the case where the engine is equipped with a turbocharger unit. The condenser and the tank are then mounted downstream of the turbine.

  In this case also, a pressure reducer device can be mounted downstream of the tank to reduce the exhaust back pressure.

  The invention is still applicable in the case where the engine is equipped with a device for partial recirculation of the exhaust gas (EGR) in the combustion chamber.

  Another aspect of the invention consists of a method for injecting water into a combustion chamber of an internal combustion engine, in particular for a motor vehicle, the water being recovered by condensation of the exhaust gases, a process in which one makes a mixture of water and fuel that is injected directly into the combustion chamber.

  Preferably, the mixture is made in the form of a water emulsion in the fuel.

  The mixture is then injected into the combustion chamber by means of a single injection device for each combustion chamber.

  The invention will be better understood from the study of a particular embodiment taken by way of non-limiting example and illustrated by the single appended figure which shows schematically the main elements of a device according to the invention.

  As illustrated in the figure, an internal combustion engine shown schematically under the reference 1 comprises a cylinder head 2 and four cylinders each provided with a combustion chamber 3. In the example shown, the fresh air admitted by the air intake pipe 4 is first compressed in a compressor 5 of a turbocharger 6 comprising the compressor 5 and an expansion turbine 7 mounted on the same mechanical drive shaft 8 as the compressor so that the turbine 7 can drive the compressor in rotation 5. The compressed air heated by the compression is fed through the pipe 9 into the intake pipe 10 connected to the various combustion chambers 3.

  The exhaust pipe 11 brings the exhaust gases to the turbine 7.

  According to the invention, the exhaust gas from the turbine 7 and already partially expanded, are fed through line 12 to the inlet of a condenser 13, for example a suitable heat exchanger. The water contained in the exhaust gas passing through the condenser 13, partially condenses and is collected in a storage tank 14 also traversed by the exhaust gas. The exhaust gas issuing from the tank 14 via the pipe 15 still passes, in the example illustrated, a pressure reducing device 16 which may be for example a pump or any other means, before being fed to the exhaust pipe 17 which further comprises complementary devices such as catalytic exhaust and / or particulate filter, not shown in the figure. The expander device 16 makes it possible to reduce the counterpressure at the exhaust, thus improving the efficiency of the turbine 7.

  According to the invention, the water in liquid form, stored in the tank 14 is conveyed by the pipe 18 to an emulsifier device 19 which also receives through the inlet pipe 20 the fuel supplied by the pump 21. A means the amount of water supplied to the emulsifier device 19 is inserted into the pipe 18 and is constituted in the example illustrated by a variable flow circulation pump 22 controlled by the control block 23.

  The emulsifier device 19 is capable of mixing the fuel from line 20 with the liquid water from line 18 in a controlled amount so as to form a homogeneous mixture. Preferably this mixture is in the form of a water emulsion in the fuel. The emulsifier device may comprise, for example, agitation means or any other suitable means known in the art for producing such an emulsion. The mixture from the emulsifier 19 is fed through line 24 onto four injectors 25, each injector being capable of injecting the mixture of fuel and water into one of the combustion chambers 3. Each combustion chamber 3 comprises therefore a single injector 25 for the simultaneous injection of the mixture of water and fuel. The use of a single injector 25 per combustion chamber 3 makes it possible to obtain a considerable space saving and to simplify the architecture of the combustion chambers. In addition, the fact of using a single injector for the simultaneous injection of fuel and water makes it possible to be certain that the injection of water is at the last moment in the cycle of the combustion engine, thus ensuring a better effectiveness of the depollution effect due to the injection of water and decreasing the risk of occurrence of knocking.

  As illustrated in the figure, the water recovered in the storage tank 14 may also come in part from a condenser device 26 forming part of an air conditioning installation equipping the motor vehicle.

  The water injection which has just been described is compatible with a strategy of operation of the engine with partial recirculation of the exhaust gas as illustrated in the figure. For this purpose, a tapping 26 is provided on the exhaust pipe 11 for a bypass line 27 for partial recirculation of the exhaust gas. The amount of the recycled exhaust gas (EGR) is regulated by a controlled valve 28 connecting the bypass line 27 to the intake pipe 10. In the example illustrated, the recycled exhaust gas can be further cooled to means of a heat exchanger 29 mounted in the recirculation line 27.

  The invention can be applied to any type of combustion engine whether it is a spark ignition engine or a diesel type engine. The invention makes it possible to greatly limit the emissions of pollutants and to improve the operation of the engine by reducing the risk of rattling while maintaining an acceptable compactness for the engine. The water injected at the same time as the fuel, in the form of a mixture, into a single injection device, comes from a storage tank fed continuously by the operation of the engine itself and, incidentally, by the air-conditioning system. of the motor vehicle.

Claims (10)

  1. Device for injecting water into a combustion chamber (3) of an internal combustion engine, in particular for a motor vehicle, of the type comprising a condenser (13) mounted on the exhaust pipe (12) of the engine and a reservoir (14) for recovering the water contained in the exhaust gas for injection, characterized in that it further comprises an emulsifier device (19) receiving fuel and water from the reservoir (14) and capable of forming a mixture of water and fuel, and an injection device (25) of said mixture in the combustion chamber (3) of the engine.   2. Device according to claim 1 characterized in that the injection device comprises a single injector for each combustion chamber.   3. Device according to one of claims 1 or 2 characterized in that it comprises a means (22,23) for regulating the amount of water supplied to the emulsifier device (19).   4. Device according to any one of the preceding claims, characterized in that the reservoir (14) is also connected to a condenser device (26) of an air conditioning system equipping the motor vehicle.   5. Device according to any one of the preceding claims, characterized in that the engine is equipped with a turbocharger (5,7), the condenser (13) and the tank (14) being mounted downstream of the turbine.   6. Device according to claim 5 characterized in that a pressure reducer device (16) is mounted downstream of the tank (14) to reduce the exhaust back-pressure.   7. Device according to any one of the preceding claims, characterized in that the engine is equipped with a device (27,28) for partial recirculation of the exhaust gas in the combustion chamber (3).   8. A method of injecting water into a combustion chamber of an internal combustion engine, in particular for a motor vehicle, the water being recovered by condensation of the exhaust gas, characterized in that a mixture of water and fuel and this mixture is injected into the combustion chamber (3).   9. The method of claim 8 characterized in that one carries out a mixture in the form of an emulsion of water in the fuel.   10. Method according to one of claims 8 or 9 characterized in that the mixture is injected by means of a single injection device (25) for each combustion chamber.