Method for managing stall phase of internal combustion engine associated with electric motor

Abstract

A method is disclosed for managing a stall phase of a heat engine associated with an electric motor when an anomaly occurs during the course of a procedure for determining the angular position of the heat engine, the method comprising the following steps once an anomaly has been detected:-implementing a diagnostic procedure associated with a fault,-reading an indicator,-determining the angular position of the heat engine,-determining the angular position of the heat engine, and-determining the angular position of the heat engine. The indicator informs about the mechanical connection of the wheels to the heat engine,-if any wheel is not connected to the heat engine, a management device managing the electric motor commands the electric motor to switch to a predetermined motor operating mode,-the motor operating mode is maintained as long as the diagnostic procedure has not been completed, and-if the diagnostic procedure has not been completed, the indicator informs the electric motor to switch to the predetermined motor operating mode. And then-commanding the electric motor to return to an operating mode in which it operates before switching to the predetermined motor operating mode.

Description

Technical Field

[0001] The present disclosure relates to a method for managing a stall phase of an internal combustion engine associated with an electric motor.

[0002] The technical field of the present disclosure is therefore that of engine management for internal combustion engines (or thermal engines or heat engines). More particularly, the present disclosure is intended for cars and the like (motorcycles, trucks, etc.) with so-called hybrid propulsion systems, that is to say vehicles comprising both an internal combustion engine and at least one electric motor.

[0003] In a hybrid vehicle, the heat engine may drive the vehicle "directly" via a gearbox, or else the heat engine is used to generate electricity which in turn is used to power the at least one electric motor driving the vehicle.

[0004] The phase just before the internal combustion engine stops is referred to herein as the stall phase: the engine is running and then stops. This stop may be intentional: the stall phase then corresponds to the stop phase between the moment the instantaneous speed of the engine drops below a threshold value (e.g. 100 revolutions per minute) and the actual stop of the internal combustion engine. The stop may also be unintentional, triggered by an uncommanded event: the stall phase then corresponds to the last few rotational moments of the internal combustion engine before it actually stops. Background Art

[0005] In an internal combustion engine, whether it is associated with an electric motor or not, the various components need to be synchronized in order to achieve a good combustion (that is to say a combustion that limits both pollutant emissions and fuel consumption).

[0006] In an internal combustion engine, the piston slides in the cylinder and drives the flywheel in rotation via a connecting rod / crankshaft system, and this movement is transmitted to the wheels of the vehicle in order to move them. In a so-called four-stroke internal combustion engine, a complete combustion cycle occurs with two revolutions (of the flywheel), i.e. 720° (called crank degrees or °C RK). In order to control the intake and exhaust of air into and out of the cylinder, at least one camshaft controls the valves. The rotation speed of the camshaft corresponds (exactly) to half the rotation speed of the flywheel (or of the crankshaft).

[0007] (Four-stroke internal combustion) engines are usually synchronized based on two pieces of information: one about the angular position of the camshaft and the other about the angular position of the flywheel (or crankshaft). The teeth are evenly arranged at the periphery of the flywheel. A singular point (usually one or two consecutive missing teeth) provides a position reference for the flywheel. A sensor (called crankshaft sensor or crank sensor) detects the passage of each tooth of the flywheel and transmits this information to the electronic control unit to calculate the position of the internal combustion engine. As soon as the singular point is detected, the control unit is able to know the angular position of the crankshaft.

[0008] Similarly, a sensor (referred to as a camshaft sensor or cam sensor) is associated with the gear to determine the position of the corresponding camshaft.

[0009] Given the difference in rotational speed of the camshaft relative to the crankshaft, it is possible to determine the position of the heat engine module 720°.

[0010] If only one signal is defective, a diagnosis must be performed in order to detect the defective signal. A backup strategy is then implemented to make it possible to continue to ensure synchronization and thus (correct) operation of the heat engine.

[0011] The diagnosis of the signal from the crankshaft sensor or the corresponding camshaft sensor is performed by checking the other signals. If the signal from the crankshaft sensor or the corresponding camshaft sensor disappears and the signal from the camshaft sensor or the corresponding crankshaft sensor is still present, this means that the thermal engine is still turning over. It is then possible to assume a diagnosis of the loss of the crankshaft sensor or the corresponding camshaft sensor signal. This diagnosis requires that the internal combustion engine has performed a certain number of revolutions in order to confirm the absence of the signal. In order to perform the diagnosis, there is a list of symptoms, each symptom corresponding to one or more anomalies (or faults). As soon as a symptom is detected (for example, a singular point in the signal or an abnormally constant signal), a diagnostic procedure is implemented to confirm or not confirm the presence of the anomaly corresponding to the symptom.

[0012] In the case of hybrid vehicles and more particularly when the heat engine is only connected to the electric machine in order to charge the battery (and therefore not directly or indirectly connected to the wheels of the vehicle), the heat engine stops very quickly. In fact, since energy is usually recovered during deceleration, the drag torque exerted on the internal combustion engine is greater, causing it to stall more quickly. In addition, when the heat engine is not connected to the wheels, it cannot benefit from the inertia of the vehicle in order to drive the vehicle.

[0013] In addition, if the crankshaft signal disappears, the internal combustion engine loses synchronization, and combustion (fuel injection) is temporarily inhibited, and thus this accelerates the stopping of the engine.

[0014] In such adverse situations, and especially when the internal combustion engine can no longer be driven by the inertia of the vehicle, the diagnostic routine will most likely not be completed before the internal combustion engine has completely stopped. Thus, in the event of a crankshaft sensor signal failure, for example, this signal failure will not be confirmed before the internal combustion engine has stopped, and the diagnosis will not be determined and therefore will not be transmitted to the driver (signal on the instrument panel).

[0015] At the next start, it will take a long time to achieve synchronization because the fault will not be fully diagnosed during the stall phase. The diagnostic procedure is then restarted and the backup strategy is implemented thereafter (if applicable). Summary of the invention

[0016] The present disclosure aims to improve this situation. The present disclosure is particularly intended to carry out a diagnosis before the internal combustion engine is stopped so that, depending on the diagnosis, a suitable strategy can be implemented as soon as a restart command is issued.

[0017] A method is proposed for managing a stall phase of an internal combustion engine associated with an electric motor in a vehicle comprising wheels when an anomaly occurs during the course of a procedure for determining the angular position of the internal combustion engine.

[0018] According to the present disclosure, once abnormal symptoms have been detected, the method comprises the following steps:

[0019] - perform diagnostic procedures in order to confirm the anomaly and / or determine its cause,

[0020] - reading an indicator which informs about the mechanical connection of the wheel to the internal combustion engine,

[0021] - if none of the wheels of the vehicle is connected to the internal combustion engine, the management means managing the electric motor command the electric motor to switch to a predetermined motor operating mode,

[0022] - the motor operating mode is maintained as long as the diagnostic procedure is not completed, then

[0023] - the management means managing the electric motor command the electric motor to return to the operating mode in which it was operating before switching to the predetermined motor operating mode.

[0024] The novelty here is that an electric motor is used to prevent the internal combustion engine from stopping immediately or stopping very (excessively) quickly, thus keeping the engine running long enough to complete the diagnostic procedure. When the internal combustion engine stops, if it stops, the fault causing the stall is then determined and the appropriate strategy (degraded or non-degraded mode) can then be implemented from the beginning of the next start. An electric motor as meant here is any type of device capable of providing mechanical torque when driven electrically. Here, this can also be any type of reversible electric machine, which, in addition to performing its motor function, is also capable of converting mechanical energy into electrical energy (alternator-starter, reversible generator set, etc.).

[0025] The features stated in the following paragraphs can optionally be implemented independently of each other or in combination with each other:

[0026] - an anomaly affecting the signal from the sensor associated with the crankshaft or the signal from the sensor associated with the camshaft;

[0027] - The diagnostic procedure is designed to observe abnormal symptoms several times in succession, increment the index when abnormal symptoms are observed, and reset the index when the abnormal symptoms no longer occur;

[0028] - the predetermined operating mode of the electric motor is an operating mode in which a setpoint rotational speed is imposed on the electric motor: in this case, the rotational speed of the electric motor may advantageously be selected such that it allows the internal combustion engine to be driven at a low idling speed, for example between 600 and 900 revolutions per minute;

[0029] At the end of the diagnostic routine, if the anomaly is confirmed, the internal combustion engine is switched to a suitable operating mode, for example a degraded mode, whereas if the anomaly is not confirmed, the operating mode of the internal combustion engine is not modified.

[0030] According to another aspect, the disclosure also relates to an electronic engine management system for an internal combustion engine, characterized in that the electronic engine management system comprises means for implementing each of the steps of the method described above. The engine management system according to the disclosure advantageously comprises at least one processor equipped with one or more memories, and input and output interfaces, the input and output interfaces comprising:

[0031] at least one input interface for receiving the data necessary for carrying out a diagnostic procedure in order to identify an anomaly and / or determine its cause, and for receiving data relating to an indicator informing about the mechanical connection of the wheel to the internal combustion engine, and

[0032] at least one output interface for issuing a command instructing the electric motor to switch to a predetermined motor operating mode and, once the diagnostic routine is completed, issuing a command instructing the electric motor to return to the operating mode in which it was operating before switching to the predetermined motor operating mode.

[0033] According to another aspect, a motor vehicle is also disclosed, comprising an internal combustion engine and at least one electric motor for driving at least one wheel of the vehicle, characterized in that the motor vehicle comprises the above-mentioned electronic management system.

[0034] Such a motor vehicle may include transmission means providing transmission between the internal combustion engine and at least one wheel, thereby allowing the internal combustion engine to drive the wheel.

[0035] Alternatively, the motor vehicle may have the internal combustion engine connected to a generator set intended to charge at least one battery. In this alternative embodiment, the internal combustion engine is not connected to the wheels (any of the wheels).

[0036] According to another aspect, a computer program is proposed, comprising instructions for implementing the method as described above when the program is executed by a processor, in particular an electronic control unit of an internal combustion engine.

[0037] According to another aspect, proposed is a non-transitory computer-readable recording medium having such a program recorded thereon. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Other features, details and advantages will become apparent upon reading the following detailed description and from examining the accompanying drawings, in which:

[0039] Figure 1 An example of an embodiment of the present disclosure is shown, which illustrates the speed and angular position changes of an internal combustion engine during a stall phase.

[0040] Figure 2 A logic diagram for implementing a method according to the present disclosure is shown.

[0041] Figure 3 is a schematic diagram of one embodiment of a vehicle implementing a method according to the present disclosure. DETAILED DESCRIPTION

[0042] The present description is given in relation to an internal combustion engine (e.g., of the four-stroke type). As known to those skilled in the art, such an internal combustion engine comprises one or more cylinders, inside each of which a piston slides, and a combustion chamber is present. Each piston is connected to a crankshaft associated with a flywheel by a connecting rod. The duration of a complete combustion cycle (intake, compression, ignition / power and exhaust) in the combustion chamber corresponds to two turns of the flywheel, i.e. 720°. The flywheel is toothed or inseparable from a toothed target, and a position sensor detects the passage of each tooth. The singular point makes it possible to detect a reference position of the flywheel. The sensor associated with the crankshaft is conventionally referred to as a "crankshaft" sensor and provides an electrical signal referred to as a "crank" signal. Each combustion chamber is also associated with a valve controlled via a camshaft. The rotational speed of the camshaft corresponds to half the rotational speed of the flywheel. Here again, a position sensor associated with the target makes it possible to determine the position of the camshaft (or each camshaft). The sensor associated with the camshaft is conventionally referred to as a "cam" sensor and provides an electrical signal referred to as a "cam" signal.

[0043] Therefore, the following description (see Figure 3) is given for a four-stroke internal combustion engine MT installed in a vehicle V having wheels R that can be driven in rotation using an electric motor R. The present disclosure applies to the case where it is either the electric motor ME or the internal combustion engine MT that can drive the wheels (not necessarily the same wheels of the vehicle), as well as the case where the driven wheels of the vehicle are driven only by at least one electric motor ME. In the latter case, the internal combustion engine MT is connected to a generator set intended to (re)charge a battery B that powers the at least one electric motor ME.

[0044] The corresponding vehicle V is then said to be "hybrid", since it comprises two motive power units operated by different energy sources. The following description relates to an internal combustion engine intended for such a vehicle. More particularly, it relates to situations in which the stalling of the engine is caused by an anomaly, or else to situations in which an anomaly occurs during an expected stalling phase.

[0045] The "crank" signal and the "cam" signal make it possible to know the angular position of the internal combustion engine precisely. These signals are used in particular to perform the injection of fuel into the engine and / or for starting the combustion of the fuel introduced into the combustion chamber. When one of these signals becomes lost or distorted, the position of the internal combustion engine is no longer precisely known, or even no longer known at all. In certain cases, fuel can no longer be injected into the engine and the engine stalls. When an abnormal symptom is detected (for example, by the absence of a signal at the moment when the signal is expected), preparations are made for starting a diagnostic procedure in a manner known to those skilled in the art in order to confirm the abnormality corresponding to the detected symptom (for example, a sensor failure) and / or in order to determine its cause.

[0046] When the internal combustion engine stalls when it is not mechanically connected to the wheels of the vehicle, the stall phase is very short and the internal combustion engine stops very quickly, since it is not driven by the inertia of the wheels and the vehicle or by any other driving force (or torque). Such a stall phase is usually (almost always) too short for the diagnostic procedure to be completed. As a result, the diagnostic procedure and / or the synchronization procedure need to be executed at the moment of a subsequent restart. Therefore, such a restart will take longer and carry a great risk of consuming more energy (electrical energy) than a normal restart.

[0047] The novel concept behind the present disclosure is to use an electric motor to drive the internal combustion engine at least during the time it takes to fully perform a diagnostic routine.

[0048] The crank signal and the cam signal are transmitted to the electronic management unit U1 (also called ECU) associated with the internal combustion engine MT. Procedures known to those skilled in the art make it possible to detect singularities in the signals received, such as, for example, a signal missing when a signal is expected, or, conversely, a signal received when no signal is expected. For example, it is necessary to observe the absence of a signal (symptom) again (usually several times) in order to confirm the presence of an anomaly. As soon as a symptom is detected, a diagnostic procedure is implemented in order to observe whether the symptom recurs, or on the other hand in order to establish that this is an isolated case and that the system is indeed operational.

[0049] The present disclosure proposes that upon detection of a symptom corresponding to the abnormality, the electric motor ME is acted upon so as to apply drive torque to the internal combustion engine experiencing the abnormality. The electric motor acts on the internal combustion engine in such a way as to prevent the internal combustion engine from stopping. The electric motor acts in such a way as to maintain, for example, an engine speed between 600 and 1000 revolutions per minute (e.g., approximately 800 revolutions per minute).

[0050] In order to (re)charge a battery that powers an electric motor driving at least one wheel of the vehicle, in the case where the wheels of the vehicle can be driven by the internal combustion engine and / or by the electric motor, and in the case where the wheels cannot be driven by the internal combustion engine (i.e., in the case where the internal combustion engine is connected to an electric machine (such as a generator set), at least one electric motor is commanded to operate in a motor operating mode (rather than as a receiver) and preferably in an operating mode in which a setpoint rotational speed is imposed on the electric motor. The above-mentioned electronic control unit (ECU) managing the internal combustion engine can, for example, generate a signal intended for the control unit U2, which controls the relevant electric motor ME so that the electric motor switches to a motor mode and preferably to a motor mode with control over the rotational speed of the (electric) motor. The rotational speed of the electric motor will depend on the transmission ratio between the electric motor and the internal combustion engine.

[0051] This strategy can also be implemented using an electric starter system for the internal combustion engine, which enables the internal combustion engine to be driven when its speed drops below a predetermined threshold (usually about 300 revolutions per minute). This type of starter system is known to those skilled in the art. Once activated, it is able to keep the internal combustion engine turning over and allow the diagnostic procedure to continue.

[0052] Thus, the internal combustion engine will not be stopped even in the absence of combustion of fuel. The diagnostic routine is completed. Depending on the results of the routine and the set points, the internal combustion engine can resume normal operation if no fault is present. The internal combustion engine can also continue to operate, but in a degraded mode suitable for the diagnosis generated by the diagnostic routine. However, if it is necessary to stop the internal combustion engine due to a fault, the detected fault is recorded in a memory provided for this purpose and the next restart is performed based on the detected fault. This restart can be a normal restart or else a restart in degraded mode. The degraded operating mode can, for example, be an operating mode without a crank signal, in which the position of the internal combustion engine is determined using only a cam signal.

[0053] Figure 1 An example of implementation of the method described above is illustrated.

[0054] In this figure, a first curve 2 illustrates the rotational speed of an internal combustion engine associated with an electric motor. A second curve 4, for its part, indicates the angular position of said internal combustion engine. These first 2 and second 4 curves show the stalling of the internal combustion engine: on the right side of the curves it can be seen that the rotational speed (first curve 2) reaches zero speed, while the second curve 4 tends towards a given position.

[0055] Figure 1 Reference numeral 10 in FIG. 1 corresponds to the detection of a symptom corresponding to an anomaly (e.g., the absence of a crank signal). Upon detection of this symptom, the electronic engine management unit managing the internal combustion engine issues a command to a predetermined electric motor so that the predetermined electric motor adopts an operating mode with control of the rotational speed. This command is Figure 1 It is obvious that there is a time offset between reference 10 and reference 12 because it took time to detect the symptom (admittedly a short time), and again, it took time to generate, transmit and execute the command. Figure 1 In the example, the speed of the internal combustion engine dropped by approximately 200 revolutions per minute between the time when the symptom was detected and the time when the electric motor began to drive the internal combustion engine to rotate.

[0056] When the method proposed by the present disclosure is implemented, the curve in the form of a broken line corresponds to the first curve 2. In the illustrated embodiment, when the diagnostic program runs as far as reference numeral 14, the electric motor here maintains a speed of approximately 800 revolutions per minute in the internal combustion engine.

[0057] When a diagnosis has been made, starting from reference numeral 14 the internal combustion engine will either continue to operate in its nominal mode depending on the diagnosis, or will enter a degraded operating mode or alternatively will still be stopped.

[0058] Figure 2is a logic diagram outlining a preferred embodiment of the method as described above.

[0059] According to the method proposed by way of non-limiting illustration, the first step 100 is to monitor and, if applicable, detect symptoms corresponding to an anomaly (especially a fault) on the crank signal or cam signal. Monitoring continues as long as no symptoms are detected (index 0 or no).

[0060] When a symptom is detected (index 1 or yes), a second step 200 may be implemented depending on the type of vehicle to which the method is applied. The illustrated embodiment relates to a vehicle in which at least one wheel (typically two or four) can be driven directly (that is to say, of course, via a gearbox) by an internal combustion engine. If the wheels are then connected to the internal combustion engine (index 1 or yes), provision is made to stop implementing the method (step 300: do nothing), since this is then equivalent to a "normal" situation for a non-hybrid vehicle and the inertia of the vehicle will allow the internal combustion engine to continue turning over long enough for the diagnostic routine to run to completion.

[0061] If the wheels are not connected to the internal combustion engine (index 0 or no), step 400 prepares to start at least one electric motor so that it operates as a motor and preferably in a mode with control of its rotation speed.

[0062] Progress monitoring is performed in step 500: progress monitoring continues as long as the diagnostic procedure has not been completed. For the diagnostic procedure, an incremental variable can be used. In order to ensure that the anomaly is real and not caused by an isolated specific situation (isolated symptom), preparation is made for the symptom to reappear multiple times. When the symptom reappears, the incremental variable is incremented, and if the symptom does not appear when "expected", the incremental variable is reset. The diagnostic procedure is completed when no symptoms appear within a predetermined duration (in terms of time or in terms of rotation angle, such as four engine revolutions). Of course, the diagnostic procedure is also completed if the observed symptoms reappear a predetermined number of times in succession. When the procedure has been completed (index 1 or ), step 600 analyzes the generated diagnosis.

[0063] If an anomaly or fault associated with the observed symptom is confirmed (index 1 or yes), a degraded mode appropriate to the anomaly (or fault) is implemented (step 700).

[0064] If an anomaly is not confirmed (index 0 or No), the internal combustion engine may continue to operate in its nominal mode.

[0065] In both cases (one is the switch to the degraded mode, the other is the internal combustion engine continues to operate in its nominal operating mode), the at least one electric motor mentioned above in step 400 returns (step 900) to the operating mode in which it had been operating before receiving the command to switch to the motor mode preferably with control of its rotational speed. It will be noted here that the electric motor could potentially have been in the motor mode with control of its rotational speed before it received the command from the internal combustion engine control unit, that is to say, in that case, the operating mode of the relevant electric motor would not be changed.

[0066] Industrial Applications

[0067] The present technical solution may find application in particular in the engine control of an internal combustion engine associated with an electric motor in the event of a stall caused by an anomaly or when a fault occurs during the stall phase.

[0068] The proposed method and the corresponding device for implementing the method make it possible to complete the diagnosis when the symptoms of an abnormality are detected without waiting to restart the internal combustion engine in order to complete (or restart) the diagnosis. This allows symptoms to be treated more quickly and allows suspected abnormalities to be confirmed or not. In some cases, the internal combustion engine can be restarted instead of allowing it to stall and stop completely, and then need to be restarted. If a restart is required, the restart is faster and consumes less energy as a result. As known to those skilled in the art, any energy saving at the moment of restart is always beneficial.

[0069] The strategy proposed in the present disclosure can also be implemented in the case of an unintentional stall. For example, if the driver makes a mistake during a gear change and instead of upshifting to the next gear ratio upshifts three gear ratios in one gear change, there is a risk that the internal combustion engine will stall, and if an anomaly occurs at this moment, the electric motor will be able to allow the diagnosis to be completed and, in addition, in the case where a stall is unavoidable, will help to make the unintentional deceleration of the vehicle less abrupt.

[0070] The present disclosure is not limited to the proposed embodiments and alternative embodiments described above, which are provided by way of example only, but the present disclosure encompasses all alternative embodiments that can be envisaged by a person skilled in the art within the intended scope of protection.

Claims

1. A method for managing a stall phase of an internal combustion engine (MT) associated with an electric motor (ME) in a vehicle (V) comprising wheels (R) when an anomaly occurs during the course of a procedure for determining the angular position of the internal combustion engine (MT), characterized in that Once the symptoms of the abnormality have been detected (100), the method comprises the following steps: - carrying out diagnostic procedures in order to confirm said anomaly and / or determine its cause, - reading an indicator (200) which informs about the mechanical connection of the wheel (R) to the internal combustion engine (MT), - if none of the wheels of the vehicle is connected to the internal combustion engine (MT), the management means (U2) managing the electric motor (ME) command the electric motor (ME) to switch to a predetermined motor operating mode (400), - maintaining said motor operating mode as long as said diagnostic procedure has not yet been completed, then - the management means (U2) managing the electric motor (ME) command the electric motor to return to the operating mode (900) in which it was operating before switching to the predetermined motor operating mode.

2. The method according to claim 1, characterized in that The anomaly affects the signal from a sensor associated with the crankshaft or the signal from a sensor associated with the camshaft.

3. The method according to any one of claims 1 or 2, characterized in that The diagnostic procedure is intended to observe the symptoms of the abnormality several times in succession, to increment the index when the symptoms of the abnormality are observed, and to reset the index when the symptoms of the abnormality no longer occur.

4. The method according to any one of claims 1 to 3, characterized in that The predetermined operating mode of the electric motor (ME) is an operating mode in which a setpoint rotational speed is imposed on the electric motor (ME).

5. The method according to claim 4, characterized in that The rotation speed of the electric motor (ME) is selected such that it allows the internal combustion engine (MT) to be driven at a low idling speed, for example between 600 and 900 revolutions per minute.

6. The method according to any one of claims 1 to 5, characterized in that At the end of the diagnostic routine, if an anomaly is confirmed (600), the internal combustion engine (MT) is switched to a suitable operating mode (700), for example a degraded mode, whereas if an anomaly is not confirmed, the operating mode of the internal combustion engine (MT) is not modified (800).

7. An electronic engine management system (U1) for an internal combustion engine, characterized in that The electronic engine management system comprises means for implementing each of the steps of the method according to any one of claims 1 to 6.

8. A motor vehicle (V) comprising an internal combustion engine (MT) and at least one electric motor (ME) for driving at least one wheel of the vehicle, characterized in that The motor vehicle comprises an electronic management system according to claim 7.

9. A motor vehicle (V) according to claim 8, characterised in that The motor vehicle comprises transmission means providing transmission between the internal combustion engine (MT) and at least one wheel (R), thereby allowing the internal combustion engine (MT) to drive the at least one wheel (R).

10. The motor vehicle (V) according to claim 8, characterized in that The internal combustion engine (MT) is connected to a generator set (ME) intended to charge at least one battery (B).

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