FR3143506A1 - METHOD FOR CONTROLLING STARTING OF AN INTERNAL COMBUSTION ENGINE DURING THE START-UP PHASE OF A HYBRID VEHICLE - Google Patents

Abstract

The subject of the present invention is a method for controlling an internal combustion engine during the activation phase of a hybrid powertrain. The method comprising a first function (MEA) controlling an activation phase (E1) of a first and second engine train (MT1, MT2) when the vehicle starts for their activation, a second torque structure function (SC ) once the first and second motor trains (MT1, MT2) have finalized their activation, the method comprising during the activation phase (E1) a step of verifying (38) the activation state of the second motor train (MT2) from the moment of detection (t3) of the rotating speed state, and control (E2) by the second torque structure function (SC) only of the first motor train (MT1 ) if the second motor train (MT2) is not activated. Figure 3.

Description

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

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

When starting a hybrid vehicle, the systems forming the powertrain are put into action for their activation. Traditionally, a so-called activation function, or MEA, of the vehicle is configured to wake up and activate each motorization element of the powertrain according to 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 called "Push Start" in English. This activation sequence is finalized when each system indicates that it is activated. Then, a second function called torque structure is responsible for controlling the internal combustion engine and the electric machines of the powertrain to respond to the driver's wishes and the needs of the other systems of the vehicle.

For example, the applicant filed patent document FR3081011A1 describing a method for distributing drive torque for a vehicle where both axles are motorized. This solution aims to improve driving comfort by anticipating a change in the operating state of the thermal engine. Patent document FR3106107A1 describes a method for optimizing an engine speed during docking which makes it possible to avoid acoustic and vibration disturbances.

In a powertrain where both axle sets are powered, during the activation phase, the electrical drive machines are activated in parallel as soon as they are electrically powered. It is then planned in this sequence that the engine is started as soon as the drive machine of the front module has completed its activation. At the end of its startup, the engine declares itself in a running and activated state. Normally, in the activation sequence it is the last component finalizing the activation of the powertrain, which authorizes the transition from the activation phase to the activation of the torque structure function. The engine is then controlled by the torque structure function in accordance with the driver's wishes.

However, it may happen that an event delays or even prevents the finalization of the activation of the rear electric drive machine, for example if its computer is electronically locked, and consequently, the torque structure function is not authorized to intervene to regulate the engine speed at idle once it is in the rotating state. Indeed, the activation function is configured only to control the torque of the drive components to allow the engine to be torn off as part of its start-up (in the case where start-up is performed by the drive components). In the case where start-up is managed by a starter, it is configured only to control this component during start-up. This situation is therefore likely to cause the engine to stall.

There is therefore a need to improve the control of the powertrain during its activation phase. An 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.

More specifically, the invention relates to a method for controlling an internal combustion engine of a hybrid powertrain comprising a first drive train comprising 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 comprising a second electric drive machine, a method in which a first function controls a phase of activation of the first and second drive trains when starting the vehicle for their activation, the actuation phase comprising starting the internal combustion engine by the first function up to a rotating speed 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 setpoints of the first and second drive trains according to the driver's torque desire once the first and second drive trains have completed their activation.

According to the invention, the method comprises, during the actuation phase, a step of verifying the activation state of the second drive train from the instant of detection of the rotating speed 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 instant of detection of the rotating speed state.

The method according to the invention may include the following additional characteristics, alone or in combination:

- control by the second torque structure function of the first drive train is authorized after a predetermined duration following the instant of detection of the rotating speed state;

- the predetermined duration is between 40 milliseconds and 50 milliseconds;

- the regulation of the internal combustion engine at idle speed during the start-up phase is operated by torque generated by the first electric machine;

- control by the second torque structure function of the first drive train is authorized until detection of the completion of the actuation phase;

- control by the second torque structure function of the first drive train is authorized until an interruption of the actuation phase is detected;

- the first electric machine is a motor machine integrated into a robotic gearbox block;

The invention envisages an electrified vehicle comprising a hybrid powertrain comprising 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 starting it, and a second drive train comprising a second electric drive machine. This hybrid powertrain also comprises a control unit controlling a first function controlling a phase of activation of the first and second drive trains when starting the vehicle for their activation, the activation phase comprising starting the internal combustion engine by the first function up to 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 setpoints of the first and second drive trains according to the torque desire of the driver once the first and second drive trains have completed their activation, the powertrain being configured for implementing the method for controlling the internal combustion engine according to any one of the preceding embodiments.

According to one variant, the first electric machine is a motor machine integrated into a robotic gearbox block.

Further contemplated is a computer program comprising instructions which, when the program is executed by a control unit, cause the program to implement any one of the embodiments of the control method.

By means of 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 to control only the front drive train so as to keep the internal combustion engine running using the electric machine. This is a software solution, which can be implemented at low cost, making it possible to control the front electric machine to keep the engine at its idle speed and avoid stalling.

Other features and advantages of the present invention will appear more clearly on reading the detailed description which follows, comprising embodiments of the invention given as non-limiting examples and illustrated by the appended drawings, in which:

schematically represents a hybrid powertrain intended to implement the invention.

represents the functional blocks of the powertrain activation function when starting the vehicle and the torque structure function realizing the driver's wishes.

represents a sequence of actuation and activation of the powertrain in accordance with the start-up control method according to the invention.

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

In reference to the , a hybrid powertrain 1 of an electrified motor vehicle capable of implementing the control method according to the invention is shown. The powertrain 1 comprises two drive trains MT1 and MT2 for the front drive wheels of the vehicle and the rear drive wheels AR, respectively. The first drive train MT1 comprises an internal combustion engine 2, a robotic gearbox block 3 integrating coupling members 6 and 7 of the drive shaft of the internal combustion engine 2 with the primary shaft of the gearbox 8. The gearbox block 3 also integrates an electric drive machine 4 coupled to the primary shaft by a torque transmission member 14, for example a gear or planetary gear train. The coupling members 6 and 7 may be clutches that can be controlled with transmissible torque. Gearbox 8 is a robotized multi-speed gearbox with electrical actuation and automatically controlled according to gear change control laws. Gearbox block 3 provides the function of transmitting engine torque to the front drive wheels of the vehicle. Other types of transmission are possible. Electric drive machine 4 is not necessarily integrated into block 3.

The electric drive machine 4 is intended to provide engine torque to the front drive wheels to move the vehicle. It can transmit engine torque individually or in addition to the internal combustion engine 2. It can also act in regenerative braking, thus recharging the energy storage system 13 of the vehicle by which it is electrically powered. In this architecture, the electric drive machine 4 is able to transmit torque to the internal combustion engine 2 through the coupling element 6 when the latter is closed and in a torque transmission state, in particular for rotating the crankshaft of the engine during a start or for regulating it at idle speed, in particular.

In addition, the front drive train MT1 comprises 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 comprises an electric motor capable of generating an engine torque allowing the internal combustion engine 2 to rotate 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 powertrain is not equipped with it.

In this example, the energy storage system 13 comprises energy storage elements formed by electrochemical cells, for example of the lithium-ion type. It is a traction battery system intended mainly 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 may be greater than or equal to approximately 48 Volts. The traction battery system 13 may be of the 48 Volt, 400 Volt, 800 Volt or higher type.

In addition, the second drive train MT2 of the rear drive wheels AR comprises a member for transmitting the engine torque 9 generated by the electric drive machine 11. The drive train MT2 comprises a member 10 for coupling the drive shaft of the electric drive machine 11 with the transmission member 9 so as to selectively transmit an engine torque to the wheels.

The powertrain 1 further comprises a DC/DC voltage converter 15 for supplying a low-voltage 12-volt battery as well as the vehicle's on-board network supplying in particular the computers of the electrical systems. Data communication means are also provided (not shown in ), for example of the CAN ("Controller Area Network") type allowing the exchange of data between the powertrain systems, in particular for activation commands, for activation status information of the powertrain systems, for start-up status information and operating speed of the internal combustion engine, for example.

In reference to the , a control unit 100 of the powertrain implements a first activation function, designated by the reference MEA, of the powertrain MT1 and MT2. The MEA function intervenes when the vehicle is started at the request of the driver via the action of the vehicle key or the actuation of the start button, an action called "Push Start" in English until all of the systems forming the powertrains of the vehicle are active and operational. The activation phase consists first of all in electrically supplying the computers of the powertrain and the electrical systems of the internal combustion engine, the electrical motor machines of the front and rear powertrain and the engine starting device, in particular. This therefore consists of supplying, waking up the computers and activating them to initiate their operation. Once the systems are activated, the MEA function hands over to a second function called torque structure for the operation of each of the torque suppliers.

The control unit 100 implements the second torque structure function, designated by the reference SC, the function of which is to determine and control the torque setpoints 104 intended for the internal combustion engine and each of the electrical drive machines once the drive trains MT1 and MT2 are put into action and they are activated. The systems control signals 102 and 103 informing the actuation function MEA when they are activated so that the latter in turn triggers the function SC via an activation signal 101, for example a status signal informing that the powertrain is activated.

The instructions are determined according to the driver's wishes. The driver's wishes are determined according to the position of the accelerator pedal, in particular. In particular, the SC function is used to control the electric motor of the front axle MT1 and the coupling device connecting the two rotating shafts so as to transmit torque to the shaft of the internal combustion engine to regulate its speed at the idle setpoint.

In nominal operation, the second SC function intervenes only once the entire powertrain is activated. However, exceptionally, when the activation of the rear electric drive machine is delayed or its computer is electronically locked, the control method according to the invention provides an anticipation mechanism authorizing the torque structure function SC to control only the front drive train MT1 when the engine is started and brought into a rotating state and the actuation phase is not yet finalized. This makes it possible in particular to control the electric drive machine 4 to transmit torque to the crankshaft of the engine 2. This mechanism makes it possible to prevent the internal combustion engine from stalling when starting the vehicle.

The control unit 100 coordinating the MEA actuation and SC torque structure functions is, for example, the vehicle supervision calculator, which may be the calculator of the internal combustion engine or of the front electric drive machine. The control unit 100 is equipped with an integrated circuit calculator and electronic memories, the calculator and the memories being configured to execute the control method according to the invention. However, this is not mandatory. Indeed, the calculator could be external to the control unit 100, while being coupled to the latter 100. In the latter case, it may itself be arranged in the form of a dedicated calculator comprising a possible dedicated program, for example. Consequently, the control unit, according to the invention, may be produced in the form of software modules (or computer modules (or even “software”)), or electronic circuits (or “hardware”), or a combination of electronic circuits and software modules.

In , an actuation sequence has been described for a powertrain as described in and controlled by the control method according to the invention, during which the activation of the rear electric motor is abnormally delayed and occurs after the internal combustion engine has started. On the abscissa, the time axis is represented, expressed in seconds, on which the time t0 represents the triggering of the starting of the vehicle by the driver from the vehicle key or the "Push Start" button. From the time t0, the actuation phase E1 of the powertrain is initiated. This phase is executed by the actuation function.

Before time t0, the driver has entered the passenger compartment of the vehicle. Opening the doors can trigger the activation of electrical systems. In this embodiment, when the doors are opened the vehicle supervisor is awakened and once activated, the robotic gearbox is activated. These initial steps, not shown in , are normally carried out within a period of approximately 2 to 3 seconds prior to the driver's start request at t0.

From this instant t0, the powertrain control method controls a closing step 30 of the coupling device connecting the drive shaft of the internal combustion engine and the primary shaft of the gearbox and a confirmation step 31 of the vehicle start request. If the start is confirmed, the control method controls the closing 32 of the high-voltage contactors connecting the traction battery with the electrical systems of the vehicle, in particular the front and rear electrical drive machines and the starting device, as well as the DC/DC voltage converter.

From time t1, the electrical systems of the vehicle are electrically powered. At this time, the control method comprises the step 35 of activating the DC/DC voltage converter transforming the voltage of the traction battery (48 volts or more) into a 12-volt voltage of the on-board network.

Furthermore, at time t1, the control method commands the activation 33 of the front electric motor, the activation 34 of the thermal engine starting device and finally the activation 36 of the rear electric motor. These activation steps provide for the performance of diagnostics and learning allowing energy transfers. Activations 33, 34, 35 and 36 are performed in parallel and are executed by the MEA activation function.

At time t2, the activation of the front electric drive machine and the starting device is finalized. In this scenario, the activation of the rear electric machine is not yet finalized. At this time t2, the control method controls the activation and starting 37 of the internal combustion engine. This step 37 provides for the rotation of the engine shaft by the starting device and/or by the electric drive machine of the front drive train.

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 loop state and the ignition activation state. An information signal is commanded to inform the MEA activation function of the vehicle supervision control unit.

In normal conditions, at this time t3, all powertrain systems would be declared activated and the torque structure function SC would intervene within a period of 10 milliseconds to a maximum of 50 milliseconds. The torque structure function is intended to determine the torque setpoints and control the powertrain in its entirety and the available torque capacities according to the driver's wishes. The internal combustion engine could possibly be kept running autonomously by fuel injection by the torque structure function SC.

However, in this scenario, the activation of the rear electric drive machine is still not finalized and the MEA activation function remains active. However, this function is not intended to control the engine and the front electric machine to maintain the idle speed. To avoid stalling of the internal combustion engine, the control method provides for a check 38, by the activation function, of the activation state of the rear drive train, in particular of the rear electric drive machine and/or of the coupling device connecting it to the rear drive wheels.

If the rear drive train is not activated at the instant t3 of detection of the rotating speed state, 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 makes it possible to avoid the internal combustion engine stalling.

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

In step E2, the idle speed maintenance of the drive shaft of the internal combustion engine is implemented by torque delivered by the front electric drive machine. The coupling device connecting them is closed and allows the transmission of the torque. This is advantageous because the reaction time for providing the necessary torque by the electric machine is short. In addition, fuel injection is avoided. Furthermore, the electric drive machine is dimensioned to provide the necessary torque at low speed and over a long period. Alternatively, the idle speed maintenance can be carried out by torque delivered by the front electric drive machine together with the electric motor of the starting device. Alternatively, only the starting device delivers the torque necessary for maintaining the idle speed.

Then, the step E2 of maintaining the idle speed by the front electric motor is controlled until the detection of the completion of the actuation phase, i.e. at time t5 when the rear electric motor informs that it is activated. Alternatively, the step E2 of maintaining the idle speed by the front electric motor is controlled until the detection of an interruption of the actuation phase E1.

Then, from time t5, the entire powertrain is declared in an activated state, i.e. the thermal engine is in a rotating state, driven by the front electric machine, the front electric machine is activated, the rear electric machine is activated, as well as the starting device. The supervision control unit ends the MEA activation function and during step E3 the torque structure function then becomes master. It determines and controls the torque setpoints of each torque supplier of the powertrain according to the driver's wishes, i.e. the position of the accelerator pedal, in particular.

The invention is described in the foregoing by way of example. It is understood that the person skilled in the art is able to produce different variant embodiments of the invention by associating, for example, the different characteristics above taken alone or in combination, without departing from the scope of the invention.

Claims (10)

Method for controlling an internal combustion engine (2) of a hybrid powertrain (1) comprising a first drive train (MT1) comprising 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) comprising a second electric drive machine (11), method in which a first function (MEA) controls an actuation phase (E1) of the first and second drive trains (MT1, MT2) when starting the vehicle for their activation, the actuation phase (MEA) comprising starting the internal combustion engine (2) by the first function (MEA) up to a running state as soon as the first electric drive machine (4) has completed its activation, and a second torque structure function (SC) controls the engine torque setpoints of the first and second drive trains (MT1, MT2) as a function of the driver's torque desire once the first and second drive trains (MT1, MT2) have been activated. MT2) have completed their activation, the method being characterized in that it comprises during the actuation phase (E1) a verification step (38) of the activation state of the second drive train (MT2) from the detection time (t3) of the rotating 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 time (t3) of the rotating speed state. Method according to claim 1, in which the control by the second torque structure function (SC) of the first drive train (MT1) is authorized after a predetermined duration (D) following the instant (t3) of detection of the rotating speed state. The method of claim 2, wherein the predetermined duration (D) is between 40 milliseconds and 50 milliseconds. Method according to any one of claims 1 to 3, in which the regulation of the internal combustion engine (2) at idle speed during the actuation phase (E1) is carried out by torque generated by the first electric machine (4). Method according to any one of claims 1 to 4, in which the control by the second torque structure function (SC) of the first drive train (MT1) is authorized until the detection of the completion of the actuation phase (E1). Method according to any one of claims 1 to 4, in which the control by the second torque structure function (SC) of the first drive train (MT1) is authorized until the detection of an interruption of the actuation phase (E1). Method according to any one of claims 1 to 6, in which the first electric machine (4) is a drive machine integrated into a robotic gearbox block (3). 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 starting it, and a second drive train (MT2) comprising a second electric drive machine (11), in which a control unit (100) controls a first function controlling an actuation phase (E1) of the first and second drive trains (MT1) when starting the vehicle for activating them, the actuation phase (E1) comprising starting the internal combustion engine (2) by the first function (MEA) up to a running state as soon as the first electric drive machine (4) has completed its activation, and in which a second torque structure function (SC) controls the engine torque setpoints of the first and second drive trains (MT1, MT2) as a function of the driver's torque desire once the first and second drive trains (MT1, MT2) have been activated. (MT1, MT2) have completed their activation, the powertrain (1) being characterized in that it is configured for implementing the method for controlling the internal combustion engine (2) according to any one of claims 1 to 7. Vehicle according to claim 8 in which the first electric machine (4) is a drive machine integrated into a robotic gearbox block (3). 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.