METHOD FOR CONTROLLING THE AUTOMATIC STARTING OF AN INTERNAL COMBUSTION ENGINE, COMPRISING PRIORITIZATION OF THE ELECTRICAL SUPPLY OF THE SYSTEMS

Abstract

The present invention relates to a method for automatically starting an internal combustion engine in a motor vehicle. The method comprises a power supply prioritization arbitration that inhibits the starting of the internal combustion engine based on an inhibition request generated during the control of a robotic system. The method includes the detection of a first inhibition request (RQ1) for starting issued by the robotic system and a second inhibition request (Tin) for starting the internal combustion engine triggered from the moment of detection (t0). The invention relates to automatic vehicle start / stop systems and power supply prioritization management, particularly for the 12V on-board electrical system. Figure 3

Description

Title of the invention: METHOD FOR AUTOMATIC STARTING A THERMAL ENGINE COMPRISING A PRIORITIZATION OF THE ELECTRICAL SUPPLY OF THE SYSTEMS

[0001] The field of the invention relates to a method for automatically starting a combustion engine of a motor vehicle. More specifically, the method relates to the automatic stopping and restarting phases of the combustion engine.

[0002] Most motor vehicles today are equipped with an automatic start / stop system for the internal combustion engine. Typically, such a system includes a DC electric starter motor powered by the vehicle's 12V electrical system. During starting, the electrical current drawn by the starter can cause a voltage drop that may affect the vehicle's electronic systems, which are also powered by 12V.

[0003] The reliability of the vehicle's on-board power supply system is vital and increasingly critical due to the growing number of robotic systems on board vehicles. In addition to the numerous engine sensors, there are trajectory control systems, robotic braking systems, and driver assistance functions, all of which also require sensors and computers to perform their automated functions.

[0004] It is common practice to implement load shedding functions for electrical systems to ensure the supply of power to other systems considered to have priority depending on the driving situation. The applicant previously filed patent document FR3059966A1, which describes a method for controlling the internal combustion engine during an automatic maneuver to guarantee the power supply to the systems. In particular, it describes a solution for evaluating the energy requirements for carrying out the maneuver, determining whether or not the internal combustion engine needs to be started before the maneuver, and finally, controlling the freezing of the internal combustion engine's operating state throughout the maneuver. This freezing prevents the engine from stopping and restarting during the maneuver to avoid current draw affecting the power supply to the 12V systems, which could disrupt or interrupt the automatic maneuver.

[0005] Furthermore, to avoid voltage drops, a voltage maintenance device, known as a DMT, is generally used in conjunction with the starter. To achieve economies of scale, some manufacturers do not integrate this device into the power supply architecture and replace it with an intelligent priority function. Control of the power supplies of the systems. For example, automatic stop and restart strategies provide that when stopped, a load shedding is commanded for certain robotic systems, for example air conditioning or power steering, to then ensure the proper running of the start and also limit the electrical consumption.

[0006] Conversely, the prioritization function assigns other robotic systems a higher priority level than the starter. This is the case, for example, with the robotic parking brake system, whose action takes priority in a restart sequence. The protocol implementation stipulates that the brake system generates the inhibition request and transmits it to the internal combustion engine control unit, which then commands the start-up prohibition accordingly. The generation of the inhibition request depends on the internal strategy of the brake system.

[0007] Some brake system equipment manufacturers configure the activation of a start-up inhibition only when an actuator draws a significant electrical current. This is the case for a brake caliper tightening / loosening operation involving hydraulic pressure regulation by a solenoid valve. In contrast, other equipment manufacturers generate an inhibition for all pressure regulation operations in the hydraulic circuit of the actuators, including fine adjustments lasting a few milliseconds. These fine adjustments are likely to cause several consecutive restart interruptions and ultimately an engine shutdown for safety reasons and to track consecutive restart failures.

[0008] To illustrate this situation, [Fig. 1] shows an automatic engine stop and restart scenario during which an inhibition request is generated twice successively, at times t0 and t3. The RG signal represents the engine speed. The lifting of the inhibition at time t0 corresponds to the application of the parking brakes. The inhibition is lifted for approximately 300 ms and ends at time t1. During this inhibition, an initial increase in engine speed is observed, which is then stopped. Next, at time t2, the engine speed is zero. At time t3, the engine initiates a restart, and at the same time, a second inhibition request is lifted by the parking brake system, due to fine-tuning over a period of a few milliseconds. This second inhibition causes the engine to stall at time t4 and finally shuts off the engine.

[0009] There is therefore a need to address the aforementioned problems. One objective of the invention is to prevent motor stalling resulting from untimely inhibition generated by a robotic system. Another objective of the invention is to provide improved motor control prioritization management capable of overseeing different strategies for generating restart inhibition requests.

[0010] More specifically, the invention relates to a method for starting control at The method involves the automatic start-up of a motor vehicle's internal combustion engine, comprising a power supply prioritization arbitration that inhibits the engine's start-up based on an inhibition request generated during the control of a robotic system. The method includes the detection of a first start-inhibition request issued by the robotic system. According to the invention, the method further includes a second start-inhibition request for the internal combustion engine, triggered from the moment of detection.

[0011] According to one variant, the second inhibition request is a time delay of a predetermined duration.

[0012] According to one variant, the predetermined duration is between 500ms and 1500ms.

[0013] According to one variant, the first inhibition request is generated at the instant of de Activation of a robotic parking brake tightening / loosening control.

[0014] According to one variant, the first inhibition request is generated at the moment of triggering an opening / closing command of a motorized element of a vehicle door.

[0015] Also provided is a motor vehicle comprising a thermal engine, a means for starting the thermal engine, at least one robotic system, a means for supplying electricity and an arbitration means capable of inhibiting the starting of the thermal engine according to an inhibition request generated during the control of the robotic system, in which the arbitration means is configured to implement the starting control method according to any one of the preceding embodiments.

[0016] According to one variant, the power supply means includes a battery and the starting means and the robotic system are powered solely by the voltage delivered by the battery.

[0017] According to one variant, a first robotic system is a motorized caliper parking brake system.

[0018] According to one variant, a second robotic system is a door system comprising a motorized element.

[0019] According to one variant, the starting means is an automatic stop and restart system starter.

[0020] The management method is advantageous in that it is compatible with the various start inhibition request management methods generated by robotic systems. Thanks to the invention and the generation of the inhibition signal by the motor control unit, the latter ignores untimely changes in an inhibition signal generated by a robotic parking brake system. This prevents successive start failures that could cause the engine to stall.

[0021] Other features and advantages of the present invention will become more apparent upon reading the following detailed description, which includes embodiments of the invention given by way of non-limiting examples and illustrated by the accompanying drawings, in which:

[0022] [Fig. 1] is a graphic representing a method for automatically starting a heat engine according to a prior art solution.

[0023] [Fig.2] is a simplified diagram of a motor vehicle powertrain intended to implement the control method according to the invention.

[0024] [Fig.3] is a graphic representing the start-up control method at automatic system executing the improved power supply prioritization management according to the invention.

[0025] In [Fig.2], a preferred embodiment of the invention is shown in which the powertrain comprises a drive chain including an internal combustion engine 10, an automated transmission 11 of engine torque to the wheels of the vehicle, a robotic braking system 12, an automatic stop and restart system 13 of the internal combustion engine 10, and an electrical power supply system 17.

[0026] The internal combustion engine 10 is controlled by a computer-based control unit 19, known as an ECU (Electronic Control Unit). The engine's stop and running states are controlled based on control signals, for example, based on the detection of a torque demand at the wheels from the driver's input, a need for cabin air conditioning, or a need to recharge the battery. The control unit continuously communicates status information to other systems to coordinate all the powertrain systems, such as information indicating whether the engine is running, stopped, or in the process of stopping, whether a start is being performed using the starter motor, or in autonomous mode, for example. The control unit 19 also monitors other powertrain systems, such as the electrical supply system 17.For this purpose, the powertrain includes means of communication, for example a CAN type communication bus (Controller Area Network), or a LIN communication bus (Local Interconnect Network).

[0027] The automated transmission 11 is an automatic or semi-automatic gearbox transmission. It includes a clutch device associated with the gearbox, which are automatically controlled by a control unit for torque transmission and gear changes.

[0028] The automatic stop and restart system 13 of the internal combustion engine 10, The system, known as "STT" for "Stop and Start," includes a means for starting the internal combustion engine 10. This starting means may comprise a starter motor or an alternator-starter. The purpose of this starting means is to activate and rotate the shaft of the internal combustion engine 10. In this preferred embodiment, the starter motor includes a solenoid that engages the starter pinion with the flywheel and a DC electric motor that rotates the shaft of the internal combustion engine 10. The starter motor is electrically powered by the power supply system 17, and the power supply is controlled by the control unit 19. The starter motor control circuit may include, for example, one or more switching relays. The starter motor is described as "heavy-duty" because it is designed to withstand several hundred thousand restarts.

[0029] A start-up sequence includes, in the event of detection of a need for a running engine, the control of a switching relay of the power supply system 17 to electrically supply the starter 13 so that it drives the shaft of the internal combustion engine 10 in rotation. When the engine shaft is being stopped (life phase where the engine is running but not injecting), in a speed range compatible with an autonomous restart, the control unit of the internal combustion engine controls the fuel injection without recourse to the starter.

[0030] The electrical power system 17 includes an extra-low voltage on-board electrical network 15, operating at voltages of approximately 12V to 14V. The on-board electrical network 15 supplies power to the powertrain systems and the control unit computers, such as the automatic start / stop system 13 and the parking brake system 12, among others. A low-voltage battery system 14, with a voltage of 12V across its terminals, supplies the on-board electrical network 15. The on-board electrical network 15 further includes an Engine Fuse Relay Box 151, referred to as the BFRM, comprising controlled switching relays to selectively supply power to each of the vehicle's systems, including the starter 13.The electrical power supply system 17 further includes an alternator 16 mechanically driven in rotation by the internal combustion engine 10, whose function is to provide a supply voltage to the electrical power supply system 17. In an alternative embodiment, the starter 13 and the alternator 16 can be replaced by an alternator-starter.

[0031] It should be noted that in this embodiment, the power supply system 17 does not include a DMT usually associated with the battery 14 and the starter 13, or a voltage converter. The starter 13 is therefore powered solely by the voltage supplied by the battery 14. The positive terminal of the battery is electrically connected to the positive terminal of the starter's electric motor. The absence of the DMT and the voltage converter helps reduce the cost of the power supply system 17.

[0032] To compensate for this absence, the control unit 19 of the internal combustion engine is therefore intended to implement a power supply prioritization module 21 during automatic stop and restart sequences. It is nevertheless envisaged that the invention can be implemented even when the power supply system 17 includes a DMT or a voltage converter, without departing from the scope of the invention.

[0033] The power supply prioritization function implemented by module 21 aims to ensure compliance with the 12V onboard network voltage constraints, thereby preventing voltage drops and malfunctions that could disrupt the electrical behavior of robotic systems and microprocessor-based computers. The invention proposes a method for managing the automatic starting of the internal combustion engine based on restart inhibition requests. These requests are generated by the robotic systems of the powertrain to establish priorities in terms of power supply management. Furthermore, the prioritization module 21 includes a means for generating another inhibition request. This request is intended to cover short-duration, unintended inhibitions, resulting, for example, from fine adjustments of the actuators of robotic systems.This request is implemented as a timer or counter that triggers upon detection of an inhibition request from a robotic system. The timer is configured to reset once it has expired.

[0034] In this embodiment, the parking brake is given a higher priority level than a request to restart the internal combustion engine. It is also envisaged that other robotic systems could have priority over the starter, for example, the vehicle's robotic door system.

[0035] The robotic system 12 is a braking system comprising actuators for tightening and loosening the wheels when the vehicle is parked and stopped. The actuators are motorized brake calipers. The braking system further includes a computer control unit 18 for automatically supervising the actuators of the system 12 according to instructions from the driver or a driver assistance system, for example, the so-called ADAS (Advanced Driver Assistance System). An automatic parking maneuver function is capable of controlling the braking system 12. More specifically, the actuators comprise a hydraulic circuit with a solenoid valve and / or an electric motor.

[0036] More specifically, the control unit 18 includes a module 22 capable of generating status and control signals, designated by the term status streams or requests, which may include requests to inhibit the starting of the internal combustion engine 10 (RQ1). RQ1 inhibition requests are generated when controlling the brake system 12 during parking brake application / release. These requests serve, in particular, to comply with the power supply constraints of the 12V on-board network.

[0037] More specifically, a request signals a first state, "No inhibition request." Therefore, there is little or no power consumption by the actuators. The actuators are in a stable state. An inhibition request RQ1 signals a second state, "Restart inhibition request for parking brake application." An inhibition request RQ1 signals a third state, "Start inhibition request for parking brake release." These last two states draw current from the 12V on-board electrical network and require prioritization of the power supply. These requests, generated by module 22, are transmitted via the communication bus 20 to the prioritization module 21 of the control unit 19.

[0038] The prioritization module 21 of the control unit 19 is capable of receiving inhibition requests generated by other robotic systems, powered by the power supply system 17, and for which a higher priority level than the starter 13 has been established. Another robotic system 24 comprising a control unit 25 may be a vehicle door system with motorized elements. A prioritization strategy may further consist of completing the closing of a motorized door or window before starting the internal combustion engine 10. In this case, the control unit 25 is configured to generate RQ2 inhibition requests for starting the internal combustion engine 10 for the purpose of prioritizing the power supply according to the invention.

[0039] A BSI module 23 is arranged to centralize information from the powertrain's systems and sensors, including battery charge status data 14. It centralizes the collected data and transmits the information via the communication bus 20 to other systems. A low charge status of the battery 14 or a request for air conditioning triggers an engine start to recharge the battery using the alternator 16 or to drive the air conditioning compressor.

[0040] In [Fig. 3], a diagram is shown of a sequence of automatic vehicle shutdown and restart, including an operation to apply the parking brake. For safety reasons, applying the parking brake takes priority over starting the engine. During this sequence, the control unit 19 of the internal combustion engine implements the automatic start control method according to the invention. The control unit 19 is equipped with an integrated circuit computer and electronic memories, the computer and memories being configured to execute the automatic start control method according to the invention. However, this is not mandatory. Indeed, the computer could be external to the control unit 19, while still being coupled to it. In the latter case, it can itself be arranged as a dedicated computer including a possible dedicated program, for example. Consequently, the control unit, according to the invention, can be implemented in the form of software modules (or computer modules), or electronic circuits (or hardware), or a combination of electronic circuits and software modules.

[0041] The graph includes an engine speed signal RG, expressed in rpm. The x-axis represents the time axis in seconds. The dashed status signal represents a first inhibition request signal RQ1, generated in this example by the parking brake system. Alternatively, the RQ1 signal could be a signal generated by a motorized door system or any other robotic system whose power supply has priority over the starter. The solid status signal Tin represents a second inhibition request signal generated by the internal combustion engine control unit.

[0042] According to this sequence, before time t0, the internal combustion engine is stopped. The engine speed RG gradually decreases. This is, for example, a situation where the vehicle is stationary and the parking brake is released. The vehicle's energy strategy automatically shuts off the engine. At time t0, the parking brake triggers a brake application. At the same time t0, a need for the running engine is detected, which triggers the starting procedure, for example, to activate the air conditioning system or recharge the battery (also known as the system's "Change of Mind").

[0043] In accordance with the 12V power supply prioritization management, the braking system requests that the internal combustion engine be prevented from starting during the application of the brakes. The braking system generates the RQ1 inhibition request between time t0 and time tl. The signal is driven high, corresponding to "Request to inhibit engine start for parking brake application." The RQ1 request lasts, for example, approximately 300 ms.

[0044] Simultaneously, an increase in engine speed RG is observed; the starter has initiated rotation of the engine shaft, but the inhibition request RQ1 causes it to be interrupted. The starter is electrically disconnected from the power supply system. At time t2, the engine speed drops to zero.

[0045] According to the invention, at the same instant t0, when the internal combustion engine control unit detects the inhibition request RQ1, the prioritization module commands a second inhibition request Tin between instant t0 and instant t4, shown in solid line. The second request Tin has the function of maintaining the inhibition during A predetermined duration is used to avoid the detection of short-lived, untimely inhibitions, such as those resulting from fine-tuning the brake system pressure. The Tin request has a duration at least strictly greater than the duration between the first rise, at time t0, and the second rise of the RQ1 request, at time t3. During the entire duration of the second Tin inhibition request, the prioritization arbitration suspends engine start-up.

[0046] In this preferred embodiment, the second Tin request is a timer, or counter, of a predetermined and configurable duration, in a value range of 500ms to 1500ms, for example 700ms. This duration is sufficient to cover the duration of the first rise until the appearance of fine pressure regulation, if applicable.

[0047] At time t4, after the time delay has elapsed, the Tin request is deactivated. There are then no more active inhibition requests. The engine is allowed to start. At time t5, it is assumed that a running engine requirement is still present. The engine start sequence is triggered. The starter is electrically powered and engages the torque transmission with the internal combustion engine shaft. The engine speed RG increases. Fuel injection is initiated, and then the engine enters running speed autonomously.

[0048] The sequence of the control method according to the invention applies identically to an automated release operation of the parking brake system, as well as to any other robotic system whose power supply takes priority over the starting of the internal combustion engine, such as, for example, a robotic door system. The invention finds advantageous application in on-board electrical power supply systems lacking a DMT or voltage converter. The invention applies to powertrains comprising an internal combustion engine equipped with an automatic stop-start system, but also to hybrid vehicles whose powertrain is equipped with an electric traction motor.

Claims

Claims

1. Method for controlling the automatic start of a thermal engine (10) of a motor vehicle, the method comprising an arbitration of prioritization of electrical power supply inhibiting the start of the thermal engine (10) as a function of an inhibition request generated during the control of a robotic system (12), the method comprising the detection of a first request for inhibition (RQ1) of the start emitted by the robotic system (12), characterized in that it further comprises a second request for inhibition (Tin) of the start of the thermal engine (10) triggered from the detection instant (tO).

2. Control method according to claim 1, characterized in that the second inhibition request (Tin) is a time delay of a predetermined duration.

3. Control method according to claim 2, characterized in that the predetermined duration is between 500ms and 1500ms.

4. Control method according to any one of claims 1 to 3, characterized in that the first inhibition request (RQ1) is generated at the instant (t0) of triggering of a robotic parking brake application / release command.

5. Control method according to any one of claims 1 to 3, characterized in that the first inhibition request (RQ1) is generated at the instant of triggering of an opening / closing command of a motorized element of a door of the vehicle.

6. Motor vehicle comprising a heat engine (10), a means for starting the heat engine (13), at least one robotic system (12), an electrical power supply means (17) and an arbitration means (21) capable of inhibiting the starting of the heat engine (10) as a function of an inhibition request generated during the control of the robotic system (12), characterized in that the arbitration means (21) is configured to implement the starting control method according to any one of claims 1 to 5.

7. Motor vehicle according to claim 6, characterized in that the electrical supply means (17) comprises a battery (14) and in that the starting means (13) and the robotic system (12) are supplied solely by the voltage delivered by the battery (14).

8. Motor vehicle according to claim 6 or 7, characterized in that that a first robotic system (12) is a motorized caliper parking brake system.

9. Motor vehicle according to any one of claims 6 to 8, characterized in that a second robotic system is a door system comprising a motorized element.

10. Motor vehicle according to any one of claims 6 to 9, characterized in that the starting means (13) is an automatic stop and restart system starter.

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