FR3020837A1 - METHOD FOR MANAGING A MOTOR VEHICLE INTERNAL COMBUSTION ENGINE IN A PUSH MODE TO REDUCE FUEL CONSUMPTION AND EMISSIONS - Google Patents

Abstract

A method of managing an internal combustion engine of a motor vehicle, to reduce fuel consumption. The engine (1) comprises an injection plant (6) and an exhaust gas pipe (8) with a catalyst (3), equipped with at least one lambda probe (4, 5) for the lambda control of the engine. air / fuel feed mixture. During the thrust phase of the engine (1) the passage of air in the catalyst (3) is neutralized.

Description

FIELD OF THE INVENTION The present invention relates to a method for managing an internal combustion engine of a motor vehicle, for reducing its fuel consumption, the internal combustion engine comprising an injection installation and a fuel injection pipe. exhaust gas with a catalyst, the exhaust pipe being equipped with at least one lambda probe for lambda regulation of the air / fuel feed mixture. The invention also relates to an installation for controlling and / or regulating an internal combustion engine and to a vehicle internal combustion engine as defined. STATE OF THE ART In today's internal combustion engines (also known as heat engines), the objective of optimization, in particular gasoline engines, lies mainly in the reduction of fuel consumption and the reduction of material emissions. polluting. Emissions of pollutants are limited by regulations which tend to be as emission-free as possible (for example currently LEV 3 (low emission vehicles).) In many cases, reducing pollutant emissions fuel consumption and thus contradicts the objective of optimizing fuel consumption, for example, heating the catalyst to its operating temperature results in an increase in fuel consumption. fuel consumption, compliance with the latest emission limits assumes that the catalyst is still operating optimally or at least close to its optimum operation to avoid emissions of pollutants downstream of the catalyst in permanent mode (by example after the catalyst heating phase) In the case of three-way catalysts, the conversion Nitrogen oxides (NOx) strongly depend on the oxygen load and the air / fuel mixture passing through the catalyst. To avoid emissions of nitrogen oxides, the catalyst must be operated so that in no phase, if possible, it is saturated completely with oxygen, as may be the case, for example, after thrust phases. extended internal combustion engine. In a push phase, the accelerator pedal is not actuated or the clutch.

In such a pushing phase, the engine control usually cuts the injection to save fuel (this is called the "thrust cut-off") but fresh air then enters the catalytic converter. . The lambda control (regulation of the lambda coefficient) which cooperates with the control or management of the engine regulates in the exhaust gas of the internal combustion engine during its active operation, the air / fuel ratio necessary for the catalyst to optimize the conversion of the oxides of nitrogen by the catalyst. For this,] the exhaust pipe is equipped with at least one lambda probe. In order to reactivate the conversion of the nitrogen oxides after the thrust phases, it is again necessary to release the oxygen from the catalyst by a rich air / fuel mixture. This "catalyst evolution" process at least partially offsets the fuel economy previously achieved during the thrust phase. The purpose of "catalyst evolution" is to restore the conversion of nitrogen oxides by the catalyst. This process is described, for example, in DE 102 40 833 A1. The release of the catalyst and the restarting of the injection after the thrust phase are operations which are not controlled or regulated in a precise manner to avoid any emission of nitrogen oxides. Therefore, the operating mode (thrust shutdown) of internal combustion engines with positive ignition (gasoline engine) is currently prohibited when they are certified for the lowest emissions. This results in a slight increase in fuel consumption of the internal combustion engine. SUMMARY OF THE INVENTION AND ADVANTAGES OF THE INVENTION The subject of the present invention is thus a process of the type defined above, characterized in that during the pushing phase of the internal combustion engine, the passage of air in the combustion chamber is neutralized. catalyst. The invention is characterized in that during the thrust phase of the internal combustion engine, a signal of a lambda probe is used. By using the signals of the lambda probes, it is concluded that the state of the catalyst is during the thrust phase. The operation can for example be used especially for long thrust phases, to determine the beginning of the oxygen saturation of the catalyst to then switch in time thrust with engine operation. For example, we can observe when the air / fuel ratio drifts towards a lean mixture. From this observation we can then control the intensity of the catalyst release function during the thrust phases. The catalyst will thus be able to neutralize, in a known manner, the nitrogen oxides thus generated. The catalyst is preferably a three-way catalyst permanently maintained in the ready state. Thus, according to the invention, it is no longer necessary to reactivate the conversion of nitrogen oxides in the catalyst after the thrust phases. It is no longer necessary to release the oxygen from the catalyst using a rich air / fuel mixture. This eliminates the need to prohibit push switching for transmission reasons. The actual fuel consumption of the internal combustion engine will be lowered despite the lowest emissions concepts.

The internal combustion engine is preferably a spark ignition engine, in particular a four-stroke gasoline engine with fuel injection and a suitable control and / or regulating installation (for example an engine management installation).

The internal combustion engine preferably has variable valve control or operation at any given time to control an intake valve or an exhaust valve or both an intake valve and a valve. exhaust so that at least during a complete cycle of the internal combustion engine, no mass flow passes through the corresponding valve. This can be done for example by a variable adjustment of the valve stroke via a zero stroke setpoint or by adjusting the phase of the camshaft by sucking up or repressing the amount of fresh air.

If, according to the method of the invention, the control or management of the engine ascertains the condition for the "thrust cutoff" operating point, then before neutralizing the injection, the intake valves and / or exhaust system so that the combustion air of the intake pipe can no longer reach the exhaust pipe. When one arrives in this state, one cuts the injection. The passage is done with an active regulation of the lambda coefficient so that the most optimal conditions for the conversion of the pollutants always prevail in the catalyst. For the remainder, during the duration of the thrust mode, the intake and / or exhaust valves are adjusted so that the combustion air of the intake duct no longer reaches the throttle pipe. exhaust. According to the process of the invention, in the pumping phases the catalyst is no longer ventilated with oxygen, which has two important advantages vis-à-vis the state of the art: a) as in push mode, the combustion air is not sucked through the catalyst, it will no longer be cooled during the pushing phases. The catalyst thus retains a higher temperature level than after that of a typical thrust cut, which at least reduces the need for post-heating the catalyst and advantageously results in economy. b) as the air stream can not pass through the catalyst, it is avoided to saturate it with oxygen or at least strongly retard this saturation (especially for long thrust phases). Thus, during the first combustion after the recovery of the injection, there will be no abrupt emission of nitrogen oxides downstream of the catalyst. The catalyst release process will be completely avoided or at least greatly reduced. The emissions from the heat engine are thus reduced accordingly. Drawings The present invention will be described below in more detail using an engine management method to reduce fuel consumption and emission. of polluting material and an internal combustion engine applying this method, shown in the accompanying drawings in which: - Figure 1 is a diagram of the device of a motor vehicle implementing the method of the invention, and - the Figure 2 shows a flow chart of the method of the invention. DESCRIPTION OF EMBODIMENTS FIG. 1 schematically and very simply shows a device for carrying out the method of the invention for reducing the fuel consumption of an internal combustion engine 1 (also called a heat engine) . The method according to the invention 15 thus relates to the thrust phase of the internal combustion engine 1. In the thrust phase, for example in a descent, the accelerator pedal and the clutch of the vehicle are not actuated and only the engine brake effect is used. FIG. 1 shows, at the inlet side of the internal combustion engine 1, an intake pipe 7 equipped with an injection device 6 and at the outlet of the internal combustion engine 1, an exhaust gas pipe 8 with a Lambda probe 4 upstream of a catalyst 3, preferably a three-way catalyst, and a lambda probe 5 downstream of the catalyst 3. Alternatively, the injection plant 6 can directly equip the cylinder head of the internal combustion engine 1 and inject the fuel directly into the combustion chamber of the internal combustion engine 1. This variant is also called direct fuel injection (abbreviated BDI). This variant is not shown in FIG. 1. The signals supplied by the lambda probes 4 and 5 are applied to an electronic control and / or control system 2, for example to the engine management installation. This installation exploits the signals and correspondingly controls the injection plant 6 to provide the desired composition of the mixture supplying the internal combustion engine 1. An application using only one of the lambda probes 4 or 5 is also possible. The internal combustion engine 1 preferably has a variable operating mode of the valves and is preferably embodied in the form of a spark ignition engine, in particular a four-stroke gasoline engine. The management of the valves means in this context of the invention that the instants of opening and / or lifting of the gas exchange valves are controlled by the control and / or regulation installation 2.

Figure 2 shows the progress of the method 100 according to the invention. In step 110, the control and / or regulation installation 2 detects the condition of the "cut-off" operating point. At the "cut-off" operating point, the control and / or regulating installation 2 usually switches for fuel economy reasons to cut off the injection, for example in a descent. In the process step 120, before cutting the injection, the intake and / or exhaust valves of the internal combustion engine 1 are nevertheless controlled so that at least during a complete cycle of the internal combustion engine 1 the combustion air does not pass from the intake pipe 7 into the exhaust pipe 8. Only when this condition is reached does the process step 130 cut off the injection The passage is effected with active regulation of the lambda coefficient so that the optimum conditions for conversion of the pollutants always prevail in the catalyst 3. During the entire duration of the thrust mode, the combustion air passage of the intake pipe 7 in the exhaust pipe 8 will be neutralized by appropriate control of the gas exchange valves. During the course of steps 110-130 and during the entire thrust phase, in parallel, in the process step 140, the signal supplied by the lambda probes 4 and 5 is continuously evaluated. By using the signals of the lambda probes. the state of catalyst 3 is concluded during the pushing phase. The operation is used, in particular for long thrust phases, to determine a start of oxygen saturation in the catalyst 3, in order to be able to switch sufficiently in time to a triggering thrust mode. For example, it can be observed how long the air / fuel mixture drifts to a lean mixture. From this observation, the intensity of the catalyst release function is controlled during the thrust phases. The catalyst can neutralize in known manner the nitrogen oxides released. In the process 100 according to the invention, after the thrust phase, it is not necessary to form a rich fuel-air mixture, to reactivate the conversion of nitrogen oxides in the catalyst 3. fuel because the catalyst 3 is permanently maintained in its operating state.

Claims (5)

CLAIMS 1 °) A method for managing an internal combustion engine of a motor vehicle, for reducing its fuel consumption, - the internal combustion engine (1) comprising an injection system (6) and an exhaust gas pipe (8) with a catalyst (3), - the exhaust pipe (8) being equipped with at least one lambda probe (4, 5) for the lambda regulation of the air / fuel feed mixture, characterized in that during the thrust phase of the internal combustion engine (1) the passage of air in the catalyst (3) is neutralized. 2) Method according to claim 1, characterized in that, in the thrust phase is exploited the signal of at least one of lambda probes (4, 5). 3) Method according to claim 1, characterized in that, in the thrust phase, the oxygen saturation of the catalyst (3) is neutralized. Method according to Claim 1, characterized in that, in the event of a break in the thrust detected by the control and / or regulating system (2), the intake valves and / or the valves are adjusted exhaust system of the internal combustion engine (1) so that the air of the intake pipe (7) can not pass into the exhaust pipe (8). 5 °) Method according to claim 1, characterized in that lambda control is effected in the passage towards the cut-off.6 °) Control and / or regulation installation (2) of a combustion engine internal (1), characterized in that it is programmed to apply the method according to any one of claims 1 to 5, to reduce its fuel consumption, - the internal combustion engine (1) having a injection plant (6) and an exhaust pipe (8) with a catalyst (3), equipped with at least one lambda probe (4, 5) for regulating lambda of the air / fuel feed mixture , and in that during the thrust phase of the internal combustion engine (1) is neutralized the passage of air in the catalyst (3). 7 °) internal combustion engine (1) of a vehicle comprising an injection plant (6) and an exhaust pipe (8) associated with the engine (1) with a catalyst (3), characterized it comprises a control and / or regulation installation (2) programmed to apply the method according to any one of claims 1 to 5, in order to reduce its fuel consumption, - the engine (1) comprising an installation of injection (6) and an exhaust gas duct (8) with a catalyst (3), equipped with at least one lambda probe (4, 5) for the lambda control of the air / fuel feed mixture and in that during the thrust phase of the internal combustion engine (1) the passage of air in the catalyst (3) is neutralized. 8 °) internal combustion engine (1) according to claim 7, characterized in that it has variable valve management. 9 °) internal combustion engine (1) according to claim 7, characterized in that it is a four-stroke gasoline engine and spark ignition.