FR3107930A1 - Engine computer and associated engine control method - Google Patents

Abstract

The invention relates to an engine controller (1) and an associated control method of an internal combustion engine comprising a set of cylinders and for each cylinder at least one injector suitable for injecting fuel into the cylinder, an intake valve. air in the cylinder and at least one spark plug adapted to initiate combustion of the fuel present in the cylinder, the internal combustion engine further comprising a three-way exhaust gas catalyst. The engine controller is configured, when an engine stop request is issued, to: - Command a stop of the ignition of each spark plug (S31), - Command, after the stop of the ignition of each spark plug, injecting fuel at a specified time in the engine cycle for a predetermined number of engine cycles before the engine physically stops (S32), the determined time being chosen so that the intake valve is closed when injecting fuel into the cylinder. Abstract figure: Figure 3a

Description

Engine computer and method for controlling an associated engine

The invention relates to an engine computer and a method for controlling an internal combustion engine.

In gasoline vehicles, three-way catalysts are used to reduce the amount of pollutants (hydrocarbons, carbon monoxide and nitrogen oxides) present in the exhaust gases.

During deceleration phases, the air/fuel mixture is lean in fuel and therefore contains a large quantity of oxygen which is stored in the catalyst. The presence of this large amount of oxygen in the catalyst prevents the three-way catalyst from working properly and effectively reducing the amount of nitrogen oxide present in the exhaust gases when restarting the engine.

It is known, for example when the automatic "stop and start" mode is activated, to inject surplus fuel when restarting in order to reduce the quantity of dioxygen stored by the catalyst and to restore good efficiency of the catalyst for the reduction of nitrogen oxides present in the exhaust gases as described in document JP200054826A1.

Until now, this method was sufficient to restore a good operating regime of the catalyst. However, as governmental anti-pollution standards have evolved, the quantity of residual pollutants leaving the catalyst is too high to meet current governmental anti-pollution standards.

An object of the present invention is therefore to reduce the quantity of pollutants at the output of a three-way catalyst of a gasoline engine during the automatic restarting of the engine in particular.

Another object of the present invention is to reduce the quantity of nitrogen oxide produced by the vehicle during restarting.

Another object of the present invention is to reduce the quantity of fuel used in order to reduce the quantity of dioxygen stored in the three-way catalyst.

There is proposed an engine controller of an internal combustion engine comprising a set of cylinders and for each cylinder at least one injector adapted to inject fuel into the cylinder, an air intake valve into the cylinder and at least one a spark plug adapted to initiate combustion of fuel in the cylinder, the internal combustion engine further comprising a three-way exhaust gas catalyst. The motor controller is further configured, during a motor stop for:
-order a shutdown of the ignition of each spark plug, and
- controlling, after stopping the ignition of each spark plug, a fuel injection at a determined moment of the engine cycle for at least one respective cylinder for a predetermined number of engine cycles before the physical stopping of the engine, the determined instant being chosen so that the intake valve is closed during the injection of fuel into the cylinder.

According to another aspect, there is provided an internal combustion engine comprising a set of cylinders and for each cylinder at least one injector adapted to inject fuel into the cylinder, an air intake valve into the cylinder and at least one a spark plug adapted to initiate combustion of fuel in the cylinder, the internal combustion engine further comprising a three-way exhaust gas catalyst. The motor further comprises a motor controller as described above.

According to another aspect, there is proposed a method for controlling an internal combustion engine comprising a set of cylinders and for each cylinder at least one injector adapted to inject fuel into the cylinder, an air intake valve in the cylinder and at least one spark plug adapted to initiate combustion of fuel in the cylinder, the internal combustion engine further comprising a three-way exhaust gas catalyst, the method being implemented by an engine controller and comprising, during an engine stop, the following steps:
- command to stop the ignition of each spark plug,
- control, after stopping the ignition of each spark plug, of fuel injection at a determined moment of the engine cycle for at least one respective cylinder for a predetermined number of engine cycles before the physical stopping of the engine, the determined instant being chosen so that the intake valve is closed during the injection of fuel into the cylinder.

According to another aspect, there is provided a computer program comprising instructions for the implementation of all or part of a method as defined herein when this program is executed by a processor. According to another aspect of the invention, there is provided a non-transitory, computer-readable recording medium on which such a program is recorded.

The characteristics exposed in the following paragraphs can, optionally, be implemented. They can be implemented independently of each other or in combination with each other:

In one embodiment, the fuel injection control and the ignition shutdown control are implemented in a single engine cycle.

In one embodiment, the engine controller is configured to obtain an estimate of a quantity of oxygen present in the catalyst after transmission of the engine stop request and to control the injection, at each engine cycle, of a quantity of fuel determined in at least one cylinder as a function of the estimated quantity of oxygen.

In one embodiment, the engine controller is further configured to obtain an estimate of catalyst efficiency and to determine the amount of fuel to inject each engine cycle based on the estimated catalyst efficiency.

In one embodiment, the engine controller is further configured to obtain an estimate of a temperature of the catalyst and to determine the quantity of fuel to be injected at each engine cycle further as a function of the temperature of the catalyst.

In one embodiment, the fuel injection instant is, for each cylinder, between a top dead center and a bottom dead center of an expansion phase.

Other characteristics, details and advantages of the invention will appear on reading the detailed description below, and on analyzing the appended drawings, in which:

shows a motor controller according to one embodiment of the invention;

illustrates a method of controlling a motor according to one embodiment of the invention;

shows a timing diagram comprising injection and ignition indicators for various engine control modes described with reference to Figure 2;

shows a comparison of a nitrogen oxide NOX level and a measured air/fuel ratio for engine control modes described with reference to Figures 2 and 3A;

illustrates a fuel injection instant as a function of the engine cycle according to one embodiment of the invention.

The drawings and the description below contain, for the most part, certain elements. They may therefore not only be used to better understand the present invention, but also contribute to its definition, if necessary.

Reference is now made to Figure 1.

FIG. 1 schematically represents a motor controller 1. The motor controller 1 comprises a computer 11, for example a microprocessor, a microcontroller or a processor, and a memory 12 capable of storing computer program instructions allowing the computer to implement implements in particular the steps of the method described below. The motor controller is able to manage different motor control modes according to information transmitted by different sensors and to control the motor through different actuators.

In particular, the motor controller 1 is able to communicate with a plurality of sensors and actuators 2, 3, 4, 5 via dedicated communication interfaces 22, 23, 24, 25, respectively. For example, engine controller 1 is able to read the position of the crankshaft, of one or more camshafts, to obtain the temperature and the state of the catalyst via various sensors. Furthermore, the engine controller is also capable of controlling fuel injection; the ignition of the spark plugs or the quantity of fuel to be injected through various actuators in particular.

Figure 2 illustrates a method of controlling an internal combustion engine according to one embodiment of the invention. The method is implemented by the motor controller which manages different operating modes of the motor by reading the values of different sensors and controlling different actuators. The different operating modes of the motor are managed by the motor controller through different control modes. Advantageously, these control modes are predefined during a motor controller configuration step and implemented when activation conditions are met.

It is considered here for example that the engine is in an initial mode of operation corresponding to a rolling phase during which the combustion of the air/fuel mixture is permitted. This is considered to be the case if at least one spark plug of an engine cylinder is ignited or actuated. The motor controller is then configured to control the motor according to a control mode A.

According to one embodiment, the motor controller checks during a step S10 whether an engine stop request has been issued. If an engine stop request is issued, it is possible, according to one embodiment, to check, during a step S20, whether other additional activation conditions are verified. For example, it can be checked whether the temperature of the catalyst belongs to an authorized nominal range and/or whether the catalyst is not defective. If this is the case, an engine stop step S30 is implemented according to a specific control mode B. Step S20 therefore comprises a sub-step for obtaining the temperature of the catalyst and a sub-step for obtaining the operating state of the catalyst by means of suitable sensors. It will be noted that when the specific engine stop control mode B is activated, it can be interrupted when one of the additional conditions of step S20 is no longer verified.

In this specific control mode B, the engine controller commands, in a step S31, a stopping of the ignition of each spark plug in each cylinder, by commanding for example the extinction of the spark plugs of each cylinder or the inhibition spark plug ignition.

Then, during a step S32, the engine controller commands fuel injection for at least one cylinder for a predetermined number of engine cycles, i.e. crankshaft revolutions, before physically stopping the engine. It should be noted that one engine cycle corresponds to two revolutions of the crankshaft, i.e. a rotation of the crankshaft target of 720°CRK with respect to its initial position. In particular, a predetermined quantity of fuel is injected at a determined instant of the engine cycle for each cylinder.

Step S32 therefore includes a step of determining the quantity of fuel to be injected for each cylinder for a predetermined number of engine cycles. The number of engine cycles during which the fuel is injected can be constant or determined according to the total quantity of fuel to be injected, for example.

Advantageously, the quantity of fuel to be injected is calculated according to one or more of the following parameters:
- a quantity of oxygen present in the catalytic converter after the engine stop request has been issued,
- the temperature of the catalyst,
- the efficiency of the catalyst.

This can be the total quantity of fuel to be injected during the engine stop phase or the quantity of fuel to be injected for each engine cycle in each cylinder.

To know the quantity of oxygen present in the catalytic converter after the engine stop request has been issued, the quantity of air introduced into the exhaust circuit during each injection cut-off is estimated. An injection cut occurs during a deceleration phase when the driver releases the accelerator, for example. By counting the number of engine cycles during which the injection into a cylinder is cut for each cylinder, it is possible to determine the quantity of air introduced into the catalyst via the exhaust circuit by admission of air into each cylinder. The quantity of oxygen present in the catalyst is obtained by multiplying the estimate of the quantity of air introduced into the catalyst by the oxygen content of the air.

Advantageously, each time the injection is resumed with ignition before the engine stop request is issued, the quantity of residual oxygen in the catalyst is determined as a function of the quantity of fuel reinjected into the catalyst. The quantity of fuel reinjected into the catalyst can be measured using the lambda probe or defined by an air/fuel ratio value to be reached, for example. It can also be determined from the amount of fuel injected into each cylinder. In this case, it is the portion of fuel in excess compared to the stoichiometric ratio allowing optimal combustion of the air introduced by the intake valve into the cylinder.

The quantity of fuel to be injected is preferably modulated according to the temperature of the catalyst and the efficiency of the catalyst.

In particular, the amount of fuel injected is reduced when the efficiency of the catalyst is reduced. The efficiency of the catalyst is estimated according to the oxygen storage capacity of the catalyst. The dioxygen storage capacity of the catalyst is measured using a probe placed downstream of the catalyst according to a method known to those skilled in the art. When the dioxygen storage capacity of the catalyst is reduced, less fuel will therefore be injected.

Advantageously, the temperature of the catalyst is also taken into account to modulate the quantity of fuel to be injected. Indeed, the temperature has an influence on the dioxygen storage capacity of the catalyst at the time of engine shutdown, the efficiency of the catalyst being evaluated most often under predefined operating conditions and with a lesser frequency than that of measurement. catalyst temperature.

The fuel injection timing that can be used is illustrated with reference to Figure 4 for a given cylinder.

Figure 4 schematically represents an engine cycle for a cylinder of a four-stroke engine. The engine cycle includes, for each cylinder, the P1 exhaust, P2 intake, P3 compression and P4 expansion phases. These different phases of the engine cycle are defined for different positions of the crankshaft corresponding to top dead centers and bottom dead centers of the piston moving in the cylinder considered. Note that the other cylinders have the same phases but shifted by a multiple of 180°CRK (i.e. for a 180° rotation of the crankshaft). The exhaust phase P1 takes place between bottom dead center PMB1 and top dead center PMH1 when the exhaust valve is open. Intake phase P2 takes place between top dead center PMH1 and bottom dead center PMB2 when the inlet valve is open. The times when the intake and exhaust valves are open are shown by the rectangles AV OP and OV OP, respectively. The compression phase P3 takes place between the bottom dead center PMB2 and the top dead center PMH2. The expansion phase P4 takes place between the top dead center PMH2 and the bottom dead center PMB1. It will be noted that the combustion of the air/fuel mixture normally takes place during the expansion phase, then called the combustion phase.

In this case, the engine controller does not allow ignition of the spark plugs. Fuel injection can be implemented with the intake valve closed and to some extent while the exhaust valve is open as shown by the double arrow INJ. Thus, the fuel present in the cylinder is sent to the catalyst during the exhaust phase, provided that it is not introduced too late when the piston rises. It should also be noted that the fuel is injected when the intake valve is closed in order to prevent fuel from being released into the intake circuit.

Advantageously, the injection can take place during the expansion phase P4 between the top dead center PMH2 and the bottom dead center PMB1 preceding the next exhaust phase P1. This limits the time spent by the fuel in the piston before being sent to the catalyst and limits the effect of diluting the fuel with the crankcase oil.

Moreover, since most engines are now direct injection, injection is advantageously done when the piston is not too close to the injector, that is to say from a top dead center in order to to avoid the deposit of fuel on the piston and the production of particles during the resumption of combustion.

In a particularly advantageous manner, there is a position of the crankshaft between the top dead center PMH2 and the bottom dead center PMB1 of the expansion phase P4 of a cylinder making it possible to limit the dilution and the production of particles. This is indicated schematically by a chain line positioned between 180° and 0° from the crankshaft target in the figure.

Furthermore, as illustrated in Figure 4, it will be noted that the intake and exhaust valves can be open at the same time and that in particular the exhaust valve can close while the exhaust valve is still opened. Thus, part of the fuel can pass through the intake valve at the end of the exhaust phase P1.

It will be noted that if the intake and exhaust valves are open simultaneously for a duration greater than a determined duration during the exhaust phase P1, part of the fuel injected into the valve ends up in the intake circuit. On the other hand, if the intake and exhaust valves are open simultaneously for a shorter time, the fuel present in the intake valve is reinjected into the cylinder during the following intake phase P2. Thus, step S20 may include the verification of an additional activation condition during which it is ensured that the intake and exhaust valves are not open simultaneously for a duration greater than a determined threshold. This check is relevant, for example, when the engine has variable valve timing and the opening and closing position of the intake and exhaust valves is variable (“Variable Valve Timing”).

This can be implemented for example by checking the angular offset values of each camshaft controlling the opening of the intake and exhaust valves, respectively, relative to a respective standard position. For a couple of angular offset values of the intake and exhaust camshafts, the implementation of step S30 can be authorized or prohibited.

It will also be noted that the fuel injection is preferably done when the engine speed is greater than a corresponding predetermined threshold of 150 revolutions per minute for example. This avoids injecting fuel in the event of loss of synchronization of the engine. It can be ensured that this threshold is not reached by choosing an appropriate number of engine cycles during which injection is authorized, for example.

The fuel injection can be done within the same engine cycle, as soon as the ignition of the spark plugs is stopped or later, for example when the engine speed is below a predetermined threshold, by example below 800 revolutions per minute.

Then, when the engine is stopped, the engine controller checks, during a step S40, if an engine restart request is issued.

If so, the motor controller implements a motor restart step S50.

Step S50 includes a sub-step for activating the starter and a sub-step for jointly activating the injection and the ignition in the same engine cycle. It will be noted that during step S30, the quantity of fuel injected may not be sufficient to completely purge the quantity of dioxygen stored by the catalyst. In this case, it is possible to reinject, during the restarting step S50, surplus fuel in order to consume the quantity of dioxygen remaining in the catalyst. Thus, advantageously, step S50 of restarting the engine includes an evaluation of the quantity of oxygen remaining in the catalyst on restart. The quantity of oxygen remaining in the catalyst is calculated according to the quantity of air introduced into the exhaust circuit during each injection cut-off and according to the quantity of fuel introduced during the injection, with or without ignition , similarly to what is described above with reference to step S30.

In one embodiment, when the additional activation conditions are not verified during step S20, the motor controller implements, during a step S60, an engine stopping step according to a control mode by defect D corresponding to that of the prior art previously described.

In this default control mode D, the engine controller commands a joint stop of the injection and the ignition in each cylinder within the same engine cycle.

Then, when the engine is physically stopped, the engine controller checks, during a step S70, if an engine restart request is issued.

If this is the case, the motor controller implements a motor restart step S80 according to a control mode C.

Step S80 comprises a sub-step of activation of the starter, and a sub-step of joint activation of the injection and the ignition for the same engine cycle in accordance with the prior art previously described. During step S80, a determined quantity of surplus fuel is injected in order to purge on restarting the dioxygen stored by the catalyst during engine stoppage in particular. In one embodiment, the restart control mode described with reference to step S50 is the same as that described here since in both control modes, the amount of excess fuel injected is calculated based on the amount of oxygen remaining in the catalytic converter on restart, when the engine restart request is issued. Since the engine shutdown implemented during step S60 does not allow the injection of fuel, the quantity of fuel to be injected is greater than the quantity of fuel injected during step S50. Moreover, the quantity of fuel to be injected during the implementation of step S80 is greater than the quantity of fuel injected during step S30 and possibly step S50. Indeed, during a standard engine stop such as that implemented during step S60, additional oxygen is stored during the engine stop.

The method described above can be applied advantageously to automatic engine stop and restart modes. The process can also be applied following a manual stopping and restarting of the engine. The engine stop and engine restart requests are then sent by the engine controller or by another dedicated computer according to the values read by the various sensors.

When the engine is stopped and restarted automatically, the engine controller or another dedicated module comprising a computer can be configured to issue an engine stop request, for example when the driver decelerates by removing his foot from the accelerator pedal, disengages and presses the brake to stop and an engine restart request can be issued when the driver releases the brake or disengages in accordance with the automatic stop and restart mode known as “stop and start” in English. In another example, the engine stop request can be sent in the absence of braking, in particular when the driver decelerates by releasing the accelerator pedal and the engine restart request can be sent when the driver presses the accelerator pedal again. acceleration, for example when the vehicle is fitted with an automatic gearbox. This is another automatic engine stop mode that occurs when there is no braking and when the engine is coasting known as “sailing stop” in English. It should also be noted that the transmission of an engine stop or engine restart request by a dedicated module is not necessarily taken into account by the engine controller and that it may be subject to the validation of additional conditions by the engine controller such as the engine temperature or the operating state of the catalytic converter, for example, before ordering the engine to stop.

When the engine is stopped and restarted manually, an engine stop/start request is sent when the driver turns the ignition key or presses the vehicle's "start/stop" button, for example. According to this variant embodiment, the restart mode may be different from that implemented during an automatic restart, in particular in that it takes into account additional parameters such as the temperature of the catalyst and may implement sub -additional steps such as for example a specific catalyst activation sub-step when the temperature of the catalyst on restarting is too low.

FIG. 3a illustrates a timing diagram representing the engine speed RM in revolutions per minute (rpm), a non-injection indicator NINJ and an ignition indicator ALLUM according to the engine stop requests ARREQ and engine restart DEMREQ emitted . The dotted line curves relate to the application of the specific stop control mode B and the associated restart mode C and the solid line curves relate to the application of the default stop control mode D and of the associated C restart mode as previously described with reference to Figure 2.

Before an engine stop request is issued (ARREQ=0), the engine is in an operating mode corresponding to a control mode A, during which fuel is injected in particular into at least one cylinder and when the spark plugs are lit to allow fuel combustion during a driving phase (NINJ=0, ALLUM=1).

According to the invention, illustrated by the various dotted curves, when an engine stop request is issued (ARREQ=1) and the engine is placed in a specific control mode B in which the ignition is switched off (ALLUM =0) but fuel injection is authorized (NINJ=0) for a predetermined number of engine cycles, the engine speed RM then decreases. Then, the injection is cut (NINJ=1) for the number of engine cycles remaining before the physical stopping of the engine and during the physical stopping of the engine (RM=0 rpm).

This takes advantage of the inertia of the engine to send the fuel through the exhaust circuit to the catalyst. Advantageously, when the number of engine cycles remaining before the physical stopping of the engine is sufficient, all of the fuel present in the cylinders is sent into the exhaust circuit before stopping the engine. There is therefore no fuel left in the cylinders when the engine is stopped.

When an engine start request is sent (DEMREQ=1), the engine is put in a control mode C during which the starter is operated then the spark plugs are ignited directly (IGNITION=1) and fuel injection (NINJ=0). It will be noted that, in this embodiment, the quantity of fuel injected depends on the quantity of dioxygen remaining in the catalyst at the time of the restart. This ensures that the quantity of nitrogen oxide emitted when restarting is reduced as much as possible. The association of the specific stop mode B with the restart mode C makes it possible to reduce the quantity of fuel to be injected to purge the catalyst compared to the association of the default stop mode D with the restart mode C known from the prior art.

The engine then enters operating mode A again in which ignition and injection are authorized together (IGNITION=1, NINJ=0).

The solid line curves illustrate the default stop D and associated restart C control mode that can be implemented for example when one or more of the additional activation conditions are not validated during step S20 described with reference to Figure 2.

When an engine stop request is sent, here for ARREQ=1 for example, the engine enters a default engine stop mode D in which injection and ignition are cut (NINJ=1, ALLUM° =°0) jointly for all the cylinders within the same engine cycle. The engine speed decreases to 0 revolutions per minute to reach the physical stop of the engine.

When an engine start request is issued, here for DEMREQ=1, the engine enters a restart mode C during which the starter is operated and then excess fuel is injected (NINJ=0) when the spark plugs are lit (ON=1). The hydrocarbons are then routed to the catalyst via the exhaust manifold. The hydrocarbons then react with the dioxygen stored in the catalyst, which has the effect of allowing a better reduction of nitrogen oxides by the catalyst.

Then, we proceed to a standard fuel injection, i.e. without surplus (NINJ=0) and the engine enters a default operating mode A.

FIG. 3b illustrates, in addition to the engine speed RM and the engine stop requests ARREQ and engine restart DEM REQ, an indicator of the level of nitrogen oxide NOX detected at the outlet of the muffler as well as an indicator the air/fuel ratio introduced into the catalyst measured by a probe λ.

As can be seen on the NOX curve, the quantity of Nitrogen Oxide measured represented by the dotted line curve (specific stop mode and associated restart) decreases compared to the solid line curve (stop mode by fault and associated restart). Indeed, when fuel is injected during the engine shutdown phase (control mode B, dotted line curve, NINJ=0), it reaches the catalytic converter before the engine restarts. On the other hand, when fuel is only injected in excess during the restart phase (restart mode C associated with the default stop mode D, curve in solid line, NINJ= 0), there is an oxide peak d nitrogen since the amount of stored oxygen is not partially reduced when the engine is restarted.

This is also visible on the curve λ with a solid line, where it can be seen that a mixture lean in fuel, i.e. with a high air/fuel ratio, arrives in the catalyst during the engine stop phase in the absence fuel injection (engine stop mode D) which tends to increase the quantity of oxygen stored by the catalytic converter. Injecting surplus fuel only when restarting the engine (restart mode associated with engine shutdown by default) is therefore not sufficient to reduce the quantity of oxygen present in the catalytic converter.

On the other hand, as illustrated by the dotted line curve, a fuel-rich mixture, i.e. for a low air/fuel ratio, arrives in the catalyst before the engine restarts, contributing to a drop in the quantity of oxygen present in the catalyst. Thus, the amount of nitrogen oxide produced after the engine restarts and resumes combustion is reduced.

It can also be seen that by injecting fuel when the engine is stopped (control mode B when the vehicle is stopped), the quantity of fuel to be injected to reduce nitrogen oxide emissions on restart is lower than that injected after a standard engine shutdown.

Claims (13)

Engine controller (1) of an internal combustion engine comprising a set of cylinders and for each cylinder at least one injector adapted to inject fuel into the cylinder, an air intake valve into the cylinder and at least one spark plug ignition adapted to initiate the combustion of fuel in the cylinder, the internal combustion engine further comprising a three-way exhaust gas catalyst,
characterized in that it is further configured, during an engine stop for:

1. Command a shutdown of the ignition of each spark plug (S31), and
2. Controlling, after stopping the ignition of each spark plug, a fuel injection at a determined instant of the engine cycle for at least one respective cylinder for a predetermined number of engine cycles before the physical stopping of the engine (S32 ), the determined instant being chosen so that the intake valve is closed during the injection of fuel into the cylinder.

An engine controller (1) according to claim 1, wherein the fuel injection control and the ignition shutdown control are implemented in a single engine cycle. Engine controller (1) according to any one of the preceding claims, in which the engine controller is configured to obtain an estimate of a quantity of oxygen present in the catalyst after the engine stop request has been issued and to control the injection , at each engine cycle, of a determined quantity of fuel in at least one cylinder as a function of the estimated quantity of oxygen. An engine controller (1) according to claim 3, wherein the engine controller is further configured to obtain an estimate of an efficiency of the catalyst and to determine the amount of fuel to be injected at each engine cycle based on the efficiency of the catalyst estimated. An engine controller (1) according to any of claims 3 or 4, wherein the engine controller is further configured to obtain an estimate of a temperature of the catalyst and to determine the amount of fuel to be injected each engine cycle further depending on the temperature of the catalyst. Engine controller (1) according to any one of the preceding claims, in which the instant of injection of the fuel is, for each cylinder, between a top dead center and a bottom dead center of an expansion phase. Internal combustion engine comprising a set of cylinders and for each cylinder at least one injector adapted to inject fuel into the cylinder, an air intake valve into the cylinder and at least one spark plug adapted to initiate combustion fuel into the cylinder, the internal combustion engine further comprising a three-way exhaust gas catalyst, the engine further comprising an engine controller according to any preceding claim. Method for controlling an internal combustion engine comprising a set of cylinders and for each cylinder at least one injector adapted to inject fuel into the cylinder, an air intake valve into the cylinder and at least one ignition adapted to initiate the combustion of fuel in the cylinder, the internal combustion engine further comprising a three-way exhaust gas catalyst, the method being implemented by an engine controller and comprising, during an engine stop, the following steps:

1. Command to stop the ignition of each spark plug (S31),
2. Control, after the ignition of each spark plug has stopped, of a fuel injection at a determined instant of the engine cycle for at least one respective cylinder for a predetermined number of engine cycles before the physical stopping of the engine (S32), the determined timing being chosen such that the intake valve is closed when injecting fuel into the cylinder.

A method according to claim 8, wherein the steps of fuel injection control and ignition shutdown control are implemented in a single engine cycle. A method according to any of claims 8 or 9, wherein said method further comprises obtaining an estimate of a quantity of oxygen present in the catalyst after issuing the engine stop request and an injection command , at each engine cycle of a determined quantity of fuel in at least one cylinder as a function of the estimated quantity of oxygen. Method according to any one of Claims 8 to 10, in which the instant of fuel injection is between a top dead center (PMH2) and a bottom dead center (PMB1) of an expansion phase (P4). Computer program comprising instructions for implementing the method according to any one of Claims 8 to 11 when this program is executed by a computer (11). Non-transitory recording medium readable by a computer on which is recorded a program for implementing the method according to claim 12 when this program is executed by a computer (11).