FR2921115A1 - METHOD FOR CONTROLLING A CARBIDE AIR INJECTOR IN A COMBUSTION CHAMBER OF A SUPERIOR INTERNAL COMBUSTION ENGINE - Google Patents

Abstract

According to a method of controlling a carbureted air injector in a combustion chamber of a supercharged internal combustion engine, non-carbureted air is injected into the combustion chamber with the injector during the exhaust phase. .Engine implementing the method.

Description

A method of controlling a carbureted air injector in a combustion chamber of a supercharged internal combustion engine. The invention relates to a method for controlling a carburetted air injector in a combustion chamber of a supercharged internal combustion engine.

US 5,170,766 discloses an injection system for an internal combustion engine by which can be injected directly into a combustion chamber of the engine a mixture of air and fuel, also called air fuel. This mixture adds to the air already present in the combustion chamber. Such a system makes it possible to independently control the quantity of air injected and that of fuel. When operating at full load of a conventional engine, the engine power is limited by the thermal conditions in the combustion chamber and the amount of air admitted during the intake phase. When the engine is supercharged, for example using a turbocharger, the amount of air admitted is greater, but it is also limited by the performance of the turbocharger. It is therefore an object of the invention to provide a control method of an engine to obtain an increased power. With this object in view, the invention relates to a method for controlling a carbureted air injector in a combustion chamber of a supercharged internal combustion engine. According to this method, non-carbureted air is injected into the combustion chamber with the injector during the exhaust phase. By ordering an injection with a zero amount of fuel, non-carbureted air is injected. It is found that such an injection during the exhaust phase has a very positive effect on the torque delivered by the engine. The injection of air during the exhaust phase makes it possible to better evacuate the residual burned gases and to reduce the temperature in the combustion chamber. This improves the intake of air admitted into the combustion chamber. Because of this better filling, more fuel can be injected, thus increasing the power of the engine. In particular, the air injection phase starts at an angular position of the crankshaft between 170 ° and 300 ° after the passage to the top dead center, preferably between 200 ° and 260 °. It is found that the maximum torque gain is obtained in these ranges for the injection of air. The 170 ° position corresponds to the end of the relaxation phase. In order to obtain the maximum power, the method is implemented during operation at full load. The invention also relates to a supercharged engine comprising at least one combustion chamber, a carburized air injector opening into the combustion chamber and control means for controlling the injector. The control means are programmed to implement the method as described above.

The engine is for example spark ignition. The invention will be better understood and other features and advantages will appear on reading the description which follows, the description referring to the accompanying drawing in which Figure 1 is a diagram showing the torque provided by an engine according to the invention. depending on the moment of the start of injection. An engine implementing a method according to the invention conventionally comprises at least one cylinder in which a piston is slidably mounted by means of a linkage. The cylinder is closed by a cylinder head, which delimits a combustion chamber between the piston, the cylinder and the cylinder head. A spark plug is attached to the cylinder head and opens into the combustion chamber. The cylinder head also has intake and exhaust valves for admitting air and venting combustion gases from the combustion chamber.

A carburetted air injector is attached to the cylinder head and also opens into the combustion chamber. The engine operates in a four-stroke cycle, with an intake phase, a compression phase, a relaxation phase and an exhaust phase. The injector injects carbureted air, that is to say a mixture of air and fuel during the compression phase. According to the invention, it also injects air, without fuel, during the exhaust phase. Referring to FIG. 1, curve a shows the gross torque obtained on the crankshaft of the engine without applying the method according to the invention, operating at full load and at 1500 revolutions per minute. The quantity of air injected represents of the order of 5% of the quantity of air admitted into the combustion chamber. Curve b represents the raw torque obtained under similar conditions, but by applying the method according to the invention, and by varying the instant of the start of air injection. This moment is marked according to the angular position of the crankshaft after the passage of the top dead center. Between 170 ° and 300 °, there is a gain in torque, the gain being more marked between 200 ° and 260 ° and up to 9%.

Claims (5)

A method of controlling a carbureted air injector in a combustion chamber of a supercharged internal combustion engine, characterized in that non-carbureted air is injected into the combustion chamber with the injector the exhaust phase. 2. Control method according to claim 1, wherein the air injection phase starts at an angular position of the crankshaft between 170 ° and 300 ° after the passage to the top dead center, preferably between 200 ° and 260 ° . 3. Control method according to claim 1, wherein it is implemented during operation at full load. 4. Supercharged engine comprising at least one combustion chamber, a carburized air injector opening into the combustion chamber, and control means for controlling the injector, characterized in that the control means are programmed to implement the process according to one of claims 1 to 3. 5. Engine according to claim 4, characterized in that it is spark ignition.