METHOD FOR CONTROLLING THE STARTING OF AN INTERNAL COMBUSTION ENGINE DURING THE START-UP PHASE OF A HYBRID VEHICLE

Abstract

The present invention relates to a method for controlling an internal combustion engine during the start-up phase of a hybrid powertrain. The method comprises a first function (MEA) controlling a start-up phase (E1) of the first and second powertrains (MT1, MT2) at vehicle start-up for their activation, a second torque structure function (SC) once the first and second powertrains (MT1, MT2) have completed their activation, the method comprising, during the start-up phase (E1), a check step (38) of the activation state of the second powertrain (MT2) from the moment (t3) of detection of the engine speed state, and the control (E2) by the second torque structure function (SC) of only the first powertrain (MT1) if the second powertrain (MT2) is not activated. Figure 3.

Description

Title of the invention: METHOD FOR CONTROLLING THE STARTING OF AN INTERNAL COMBUSTION ENGINE DURING THE START-UP PHASE OF A HYBRID VEHICLE

[0001] The field of the invention relates to a method for controlling the start-up of an internal combustion engine during the activation phase of the systems of a hybrid vehicle powertrain.

[0002] When a hybrid vehicle is started, the systems comprising the powertrain are activated. Typically, a vehicle activation function, or MEA, is configured to wake up and activate each powertrain component in a controlled sequence as soon as it receives a request from the driver via an action of the key or the vehicle start button, an action known as "Push Start." This activation sequence is completed when each system indicates that it is activated. Subsequently, a second function, called the torque structure, is responsible for controlling the internal combustion engine and the electric motors of the powertrain to respond to the driver's input and the needs of the other vehicle systems.

[0003] The applicant, for example, filed patent document FR3081011Al describing a method for distributing drive torque for a vehicle where both axles are powered. This solution aims to improve ride comfort by anticipating a change in the operating state of the internal combustion engine. Patent document FR3106107A1 describes a method for optimizing engine speed during docking, which helps to avoid noise and vibration.

[0004] In a powertrain where both axle assemblies are powered, during the start-up phase, the electric drive machines are activated in parallel as soon as they are electrically supplied. Subsequently, in this sequence, the engine is scheduled to start as soon as the drive machine of the front module has completed its activation. At the end of its start-up, the engine is declared to be running and activated. Normally, in the start-up sequence, it is the last component completing the activation of the powertrain, which allows the transition from the start-up phase to the activation of the torque structure function. The engine is then controlled by the torque structure function according to the driver's input.

[0005] However, it may happen that an event delays or even prevents the final activation of the rear electric drive machine, for example if its control unit is electronically locked, and consequently, the torque structure function is not The system is not authorized to intervene to regulate the engine speed at idle once the engine is running. Indeed, the start-up function is configured solely to drive the drive components to allow the engine to start (when starting is performed by the drive components). When starting is managed by a starter motor, the system is configured only to drive that component during startup. This situation is therefore likely to cause the engine to stall.

[0006] There is therefore a need to improve the control of the powertrain during its start-up phase. One objective of the invention is to prevent stalling of the internal combustion engine when the activation of the rear axle drive is delayed once the engine is started and running.

[0007] More specifically, the invention relates to a method for controlling an internal combustion engine of a hybrid powertrain comprising a first drive train including at least the internal combustion engine and a first electric machine capable of transmitting torque to the internal combustion engine, and a second drive train including a second electric drive machine, method in which a first function controls a phase of starting the first and second drive trains at the start of the vehicle for their activation, the start-up phase including the starting of the internal combustion engine by the first function until a running state as soon as the first electric drive machine has finalized its activation,and in which a second torque structure function controls the engine torque commands of the first and second drive trains according to the driver's torque preference once the first and second drive trains have completed their activation.

[0008] According to the invention, the method includes during the activation phase a step of verifying the activation state of the second drive train from the moment of detection of the rotating state, and a step of controlling by the second torque structure function only the first drive train to regulate the internal combustion engine at idle speed if the second drive train is not activated after the moment of detection of the rotating state.

[0009] The method according to the invention may include the following additional features, alone or in combination:

[0010] - the control by the second torque structure function of the first train of mo Torisation is authorized after a predetermined duration following the moment of detection of the rotating operating state;

[0011] - the predetermined duration is between 40 milliseconds and 50 milliseconds;

[0012] - the regulation of the internal combustion engine at idle speed during the phase The activation is carried out by the torque generated by the first electric machine;

[0013] - the control by the second torque structure function of the first train of mo Torisation is permitted until the finalization of the activation phase is detected;

[0014] - the control by the second torque structure function of the first train of mo Torisation is permitted until an interruption of the activation phase is detected;

[0015] - the first electric machine is a drive machine integrated into a block of automated gearbox;

[0016] According to the invention, an electrified vehicle is envisaged comprising a hybrid powertrain including a first drive train comprising at least one internal combustion engine and a first electric machine capable of transmitting torque to the internal combustion engine for its starting, and a second drive train comprising a second electric drive machine.This hybrid powertrain also includes a control unit that operates a first function controlling a start-up phase of the first and second drive trains at vehicle start-up for their activation, the start-up phase including the starting of the internal combustion engine by the first function until a running state as soon as the first electric drive machine has completed its activation, and in which a second torque structure function controls the engine torque commands of the first and second drive trains according to the driver's desired torque once the first and second drive trains have completed their activation, the powertrain being configured for the implementation of the internal combustion engine control method according to any of the preceding embodiments.

[0017] According to one variant, the first electric machine is a drive machine integrated into a robotic gearbox block.

[0018] A computer program is also envisaged comprising instructions which, when the program is executed by a control unit, lead the latter to implement any one of the embodiments of the control method.

[0019] Thanks to the invention, in the exceptional case where the rear drive train is delayed in its activation or electronically locked, the control unit is configured to anticipate the activation of the torque structure function in order to drive only the front drive train so as to keep the internal combustion engine running by means of the electric motor. This is a low-cost, implementable software solution that allows the front electric motor to be controlled to maintain the engine at its idle speed and prevent stalling.

[0020] Other features and advantages of the present invention will become apparent later clearly understood from the detailed description that follows, which includes embodiments of the invention given by way of non-limiting examples and illustrated by the attached drawings, in which:

[0021] [Fig. 1] schematically represents a hybrid powertrain intended to implement the invention.

[0022] [Fig.2] represents the functional blocks of the powertrain activation function at vehicle start-up and the torque structure function realizing the driver's will.

[0023] [Fig.3] represents a sequence of starting and activating the powertrain according to the starting control method according to the invention.

[0024] The invention applies to hybrid electrified vehicles, that is to say comprising one or more electric drive machines and power electronics, preferably motor vehicles, but not only such as a truck, bus, airplane, tractor, or even ships.

[0025] With reference to [Fig. 1], a hybrid powertrain 1 of an electrified motor vehicle is shown, capable of implementing the control method according to the invention. The powertrain 1 comprises two drive assemblies MT1 and MT2, respectively for the front drive wheels (AV) and the rear drive wheels (AR) of the vehicle. The first drive assembly MT1 comprises an internal combustion engine 2, a robotized gearbox 3 incorporating coupling elements 6 and 7 for the drive shaft of the internal combustion engine 2 with the input shaft of the gearbox 8. The gearbox 3 also incorporates an electric drive machine 4 coupled to the input shaft by a torque transmission element 14, for example, a gear or planetary gear set. The coupling elements 6 and 7 may be torque-controlled clutches.The gearbox 8 is a multi-speed automated gearbox with electrical actuation and automatic control based on gear shift control laws. The gearbox unit 3 transmits engine torque to the front drive wheels of the vehicle. Other transmission types are possible. The electric drive machine 4 is not necessarily integrated into the unit 3.

[0026] The electric drive machine 4 is designed to provide torque to the front drive wheels (AV) to move the vehicle. It can transmit torque independently or in conjunction with the internal combustion engine 2. It can also act as a regenerative brake, thereby recharging the vehicle's energy storage system 13, from which it is electrically powered. In this configuration, the electric drive machine 4 is capable of transmitting torque to the internal combustion engine 2 through the coupling element 6 when the latter is closed and in a torque transmission state, particularly for rotating the engine crankshaft during starting or for regulating its idle speed, in particular.

[0027] Furthermore, the front drive train MT1 includes a starting device 5 coupled to the drive shaft of the internal combustion engine by a torque transmission element, in this example a belt. The starting device 5 includes an electric motor capable of generating motor torque to rotate the internal combustion engine 2 during starting. The starting device can also generate electrical energy and recharge the energy storage system 13. The starting device can be used alone or in conjunction with the electric drive machine 4 to start the internal combustion engine 2. The starting device 5 is not mandatory. Alternatively, the drive train is not equipped with it.

[0028] In this example, the energy storage system 13 comprises energy storage elements formed by electrochemical cells, for example, lithium-ion cells. It is a traction battery system intended primarily for powering the electric drive machine 4, the starting device 5, and a second electric drive machine 11 integrated into the MT2 drive train of the rear drive wheels AR of the vehicle. The traction battery system provides a supply voltage that can be greater than or equal to approximately 48 volts. The traction battery system 13 can be of the 48-volt, 400-volt, 800-volt, or higher type.

[0029] In addition, the second drive train MT2 of the rear drive wheels AR includes a transmission element for the motor torque 9 generated by the electric drive machine 11. The drive train MT2 includes a coupling element 10 of the motor shaft of the electric drive machine 11 with the transmission element 9 so as to selectively transmit motor torque to the wheels.

[0030] The powertrain 1 further includes a DC / DC voltage converter 15 for supplying a 12-volt low-voltage battery and the vehicle's on-board network, which notably supplies the electrical system control units. It also includes data communication means (not shown in [Fig. 1]), for example, of the CAN ("Controller Area Network") type, enabling data exchange between the powertrain systems, particularly for activation commands, for activation status information of the drive train systems, and for starting status and engine speed information of the internal combustion engine, for example.

[0031] With reference to [Fig. 2], a powertrain control unit 100 implements a first activation function, designated by the reference MEA, of the The MT1 and MT2 powertrains of the powertrain are activated by the MEA function when the vehicle is started, either by turning the key or pressing the start button (a "push start" action). This activation continues until all the vehicle's powertrain systems are active and operational. The activation phase begins by supplying power to the powertrain control units and the electrical systems of the internal combustion engine, the electric drive machines of the front and rear powertrains, and the engine starting system. This involves powering, waking, and activating the control units to begin their operation. Once the systems are activated, the MEA function hands over to a second function, the torque structure, which controls the operation of each torque source.

[0032] The control unit 100 implements the second torque structure function, designated by the reference SC, whose function is to determine and control the torque commands 104 to the internal combustion engine and each of the electric drive machines once the drive trains MT1 and MT2 are started and activated. The systems control signals 102 and 103 informing the start-up function MEA when they are activated so that the latter in turn triggers the SC function via an activation signal 101, for example a status signal indicating that the drive train is activated.

[0033] The instructions are determined according to the driver's intent. The driver's intent is determined according to the position of the accelerator pedal, in particular. Specifically, the SC function allows the electric drive machine of the front axle MT1 and the coupling device connecting the two rotating shafts to be controlled in order to transmit torque to the internal combustion engine shaft to regulate its speed to the idle setpoint.

[0034] In normal operation, the second SC function intervenes only once the entire powertrain is activated. However, in exceptional circumstances, when the activation of the rear electric drive unit is delayed or its control unit is electronically locked, the control method according to the invention provides an anticipation mechanism allowing the torque structure function SC to drive only the front drive train MT1 when the engine has started and is running, and before the start-up phase is complete. This allows, in particular, the electric drive unit 4 to be driven to transmit torque to the crankshaft of the engine 2. This mechanism prevents the internal combustion engine from stalling during vehicle start-up.

[0035] The control unit 100 coordinating the MEA activation and SC torque structure functions is, for example, the vehicle monitoring computer, This could be the control unit for the internal combustion engine or the front electric drive. The control unit 100 is equipped with an integrated circuit control unit and electronic memory, the control unit and memory being configured to execute the control method according to the invention. However, this is not mandatory. Indeed, the control unit could be external to the control unit 100, while still being coupled to it. In this latter case, it could itself be arranged as a dedicated control unit including, for example, a dedicated program. Consequently, the control unit, according to the invention, can be implemented in the form of software modules, electronic circuits, or hardware, or a combination of electronic circuits and software modules.

[0036] In [Fig. 3], a start-up sequence for a powertrain as described in [Fig. 1] and controlled by the control method according to the invention is described, during which the activation of the rear electric drive machine is abnormally delayed and occurs after the internal combustion engine has started. The time axis, expressed in seconds, is represented on the x-axis, where time t0 represents the activation of the vehicle by the driver using the vehicle key or the "Push Start" button. From time t0, the powertrain start-up phase El is initiated. This phase is executed by the start-up function.

[0037] Before time t0, the driver has entered the vehicle's passenger compartment. Opening the doors can trigger the activation of electrical systems. In this embodiment, upon opening the doors, the vehicle supervisor is awakened, and once activated, the automated gearbox is engaged. These initial steps, not shown in [Fig. 3], normally occur within approximately 2 to 3 seconds prior to the driver's start request at t0.

[0038] From this instant t0, the powertrain control process drives a closing step 30 of the coupling device connecting the internal combustion engine's drive shaft and the gearbox's input shaft, and a confirmation step 31 of the vehicle start request. If the start is confirmed, the control process commands the closing 32 of the high-voltage contactors connecting the traction battery with the vehicle's electrical systems, including the front and rear electric drive machines and the starter device, as well as the DC / DC voltage converter.

[0039] From time t1, the vehicle's electrical systems are powered. At this time, the control process includes the activation step 35 of the DC / DC voltage converter transforming the traction battery voltage (48 volts or more) into a 12-volt type voltage of the on-board network.

[0040] Furthermore, at time t1, the control process commands the activation 33 of the front electric drive machine, the activation 34 of the internal combustion engine starting device, and finally the activation 36 of the rear electric drive machine. These activation steps include diagnostic and learning operations enabling energy transfers. Activations 33, 34, 35, and 36 are performed in parallel and are executed by the activation function MEA.

[0041] At time t2, the activation of the front electric drive machine and the starting device is complete. In this scenario, the activation of the rear electric drive machine is not yet complete. At this time t2, the control method commands the activation and starting 37 of the internal combustion engine. This step 37 involves rotating the engine shaft by the starting device and / or by the electric drive machine of the front drive train.

[0042] At time t3, the internal combustion engine is running. The running state is detected from a parameter representing the engine shaft speed, the air loop closure state, and the ignition activation state. An information signal is triggered to inform the MEA activation function of the vehicle's supervisory control unit.

[0043] Under normal conditions, at time t3, all powertrain systems would be declared activated, and the torque structure function SC would intervene within a period of 10 to 50 milliseconds. The torque structure function is designed to determine torque setpoints and control the entire powertrain and available torque capabilities according to the driver's input. The internal combustion engine could optionally be kept running autonomously by fuel injection via the torque structure function SC.

[0044] However, in this scenario, the activation of the rear electric drive machine is still not complete, and the MEA activation function remains active. This function is not designed to control the engine and the front electric drive machine to maintain idle speed. To prevent stalling of the internal combustion engine, the control method includes a check 38, by the activation function, of the activation status of the rear drive train, in particular the rear electric drive machine and / or the coupling device connecting it to the rear drive wheels.

[0045] If the rear drive train is not activated at time t3 of the detection of the operating speed, then the control method provides for the control E2, by the second torque structure function, of the front drive train only, to regulate the internal combustion engine at idle speed. This early intervention of the torque structure function prevents the engine from stalling. internal combustion.

[0046] Preferably, the E2 control of the front drive train by the torque structure function SC is executed after a predetermined time D following the time t3 of detection of the rotating state. The predetermined time D is between 40 milliseconds and 50 milliseconds. This is a sufficiently short time following the rotating state declaration to avoid stalling.

[0047] During step E2, maintaining the idle speed of the internal combustion engine's drive shaft is achieved by torque delivered by the front electric drive unit. The coupling device connecting them is closed and allows the transmission of torque. This is advantageous because the reaction time for the electric drive unit to provide the necessary torque is short. Furthermore, fuel injection is avoided. In addition, the electric drive unit is sized to provide the necessary torque at low speeds and for extended periods. Alternatively, maintaining the idle speed can be achieved by torque delivered by the front electric drive unit in conjunction with the electric motor of the starter device. Alternatively, the starter device alone delivers the torque required for maintaining the idle speed.

[0048] Next, step E2, which maintains the idle speed using the front electric drive machine, is controlled until the completion of the activation phase is detected, i.e., at time t5 when the rear electric drive machine signals that it is activated. Alternatively, step E2, which maintains the idle speed using the front electric drive machine, is controlled until an interruption of the activation phase EL is detected.

[0049] Then, from time t5, the entire powertrain is declared to be in an activated state, meaning that the internal combustion engine is running, driven by the front electric motor, the front electric motor is activated, the rear electric motor is activated, as is the starter device. The supervisory control unit terminates the MEA activation function, and during step E3, the torque structure function then becomes dominant. It determines and controls the torque setpoints of each torque provider in the powertrain according to the driver's input, i.e., the accelerator pedal position, in particular.

[0050] The invention is described above by way of example. It is understood that a person skilled in the art is able to carry out different variant embodiments of the invention by combining, for example, the different features above taken alone or in combination, without departing from the scope of the invention.

Claims

Demands

1. A method for controlling an internal combustion engine (2) of a hybrid powertrain (1) comprising a first drive train (MT1) including at least the internal combustion engine (2) and a first electric machine (4) capable of transmitting torque to the internal combustion engine, and a second drive train (MT2) including a second electric drive machine (11), wherein a first function (MEA) commands a start-up phase (El) of the first and second drive trains (MT1, MT2) at vehicle start-up for their activation, the start-up phase (MEA) including the starting of the internal combustion engine (2) by the first function (MEA) until a running state as soon as the first electric drive machine (4) has completed its activation, and a second torque structure function (SC) drives the engine torque commands of the first and second drive trains (MT1,MT2) depending on the driver's torque preference once the first and second drive trains (MT1, MT2) have completed their activation, the method being characterized in that it comprises during the activation phase (E1) a verification step (38) of the activation state of the second drive train (MT2) from the detection instant (t3) of the running speed state and a control step (E2) by the second torque structure function (SC) only of the first drive train (MT1) to regulate the internal combustion engine (2) at idle speed if the second drive train (MT2) is not activated after the detection instant (t3) of the running speed state.

2. Method according to claim 1, wherein the control by the second torque structure function (SC) of the first drive train (MT1) is allowed after a predetermined time (D) following the instant (t3) of detection of the rotating operating state.

3. A method according to claim 2, wherein the predetermined duration (D) is between 40 milliseconds and 50 milliseconds.

4. A method according to any one of claims 1 to 3, wherein the regulation of the internal combustion engine (2) at idle speed during the start-up phase (El) is operated by torque generated by the first electric machine (4).

5. A method according to any one of claims 1 to 4, wherein the control by the second torque structure function (SC) of the first drive train (MT1) is permitted until the finalization of the activation phase (El) is detected.

6. A method according to any one of claims 1 to 4, wherein the control by the second torque structure function (SC) of the first drive train (MT1) is allowed until the detection of an interruption of the activation phase (El).

7. A method according to any one of claims 1 to 6, wherein the first electric machine (4) is a drive machine integrated into a robotic gearbox block (3).

8. Electrified vehicle comprising a hybrid powertrain (1) comprising a first drive train (MT1) comprising at least one internal combustion engine (2) and a first electric machine (4) capable of transmitting torque to the internal combustion engine (2) for its starting, and a second drive train (MT2) comprising a second electric drive machine (11), in which a control unit (100) drives a first function controlling an activation phase (El) of the first and second drive trains (MT1) at vehicle start-up for their activation, the activation phase (El) comprising the starting of the internal combustion engine (2) by the first function (MEA) until a running state as soon as the first electric drive machine (4) has completed its activation,and wherein a second torque structure (SC) function drives the engine torque commands of the first and second drive trains (MT1, MT2) according to the driver's torque intent once the first and second drive trains (MT1, MT2) have completed their activation, the powertrain (1) being characterized in that it is configured for the implementation of the method for controlling the internal combustion engine (2) according to any one of claims 1 to 7.

9. Vehicle according to claim 8 in which the first electric machine (4) is a drive machine integrated into a robotized gearbox block (3).

10. Computer program comprising instructions which, when the program is executed by a control unit (100), cause the latter to implement the control method according to any one of claims 1 to 7.

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