FR3052190A1 - METHOD FOR AUTHORIZING THE STOPPING OF THE THERMAL MOTOR OF A MOTOR VEHICLE - Google Patents

Abstract

The invention relates to a method for authorizing the stopping of the engine of a motor vehicle prior to a circulating mode of said motor vehicle with the engine stopped, said vehicle comprising a starting member (AD) of the engine and at least one battery (B) for supplying electrical power to said starting member (AD), the method comprising a step of testing the capacity of the battery (B) to feed the starting member (AD) and a authorization step of stopping the engine if the battery (B) is able to supply the starting member (AD) to start the engine.

Description

METHOD FOR AUTHORIZING THE STOPPING OF THE THERMAL MOTOR OF A

MOTOR VEHICLE

[001] The invention relates, in general, the management of the power supply of a vehicle, in particular in a motor vehicle.

[002] The invention relates more particularly to a method for authorizing the "high speed" stop of the engine of a motor vehicle according to an evaluation of the available electrical power.

[003] A motor vehicle comprises in known manner different electrical equipment that may be necessary for the safety of the vehicle, such as braking, steering, airbag, etc., or be called "comfort", such as only heated seats, the heating of the passenger compartment, etc. These electrical equipment are supplied with electricity by electrical energy produced by the heat engine and by electrical energy stored in an electrochemical storage, such as a battery.

[004] Today, it is known a function called "sailing" in English terminology, meaning "cruise", to reduce the discharge of polluting gases, such as carbon dioxide emitted by the engine of the vehicle, in stopping said engine and opening the drive chain, in particular the clutch, while the vehicle is traveling, in particular during a deceleration phase of the vehicle. The vehicle then advances thanks to its inertia.

[005] However, following the shutdown of the engine, this stop also causing the stop of the production of electrical energy by the engine, only the battery supplies the electrical equipment of the vehicle.

In this context, it is known from US2014 / 0067241 A1 to monitor the state of charge of the battery when the "cruise" function is implemented. The restart of the engine is then controlled when the state of charge is below a safety threshold, which ensures the power supply of the various electrical equipment of the vehicle during the "cruise" mode.

[007] However, when starting the heat engine, a large amount of electrical energy must be delivered by the battery to power the starter system of the motor vehicle. Also, the "cruise" mode is generally activated only for a low vehicle speed (less than 20 km / h) in order, in particular, to limit the risks in the event of a problem with the battery preventing restarting the engine.

[008] To activate the "cruise" mode at a speed greater than 20 km / h, it is known to integrate a backup electrochemical energy storage system in the vehicle to ensure the restart of the engine at the end of "cruise" mode as well as the power supply of safety electrical equipment during "cruise" mode. However, the use of such a backup system requires the diagnosis of the latter as well as a switching system of the supply of electrical equipment, which has the disadvantage of inducing an increase in the number of components present in the motor vehicle and therefore the mass of said vehicle.

[009] The invention therefore aims to overcome these disadvantages by providing a method for authorizing the stopping of the engine of a vehicle, in particular at a speed greater than 20 km / h, to ensure the proper operation of the motor vehicle in "cruise" mode and to guarantee the restart of the engine at the end of cruise mode.

To achieve this result, the present invention relates to a method for authorizing the stopping of the engine of a motor vehicle, prior to a circulating mode of said motor vehicle with the engine stopped, said vehicle comprising a starting member of the heat engine and at least one electric power supply battery of said starting member, the method comprising: a step of receiving a stop command of the heat engine, a step of testing the capacity of the battery to supply the starting member, and - a step of authorizing the stopping of the engine if the battery is adapted to supply the starting member to start the engine.

With the method according to the invention, the battery is tested before shutdown of the engine to check the capacity of the latter to supply the starting member of the engine and the consumers powered during the engine stop thermal and vehicle safety functions. Thus, when launching the "cruising" mode of operation of the vehicle, it is possible to check the capacity of the battery to allow the restart of the engine at the end of the "cruise" mode while supplying the consumers powered during operation. shutdown of the engine and the safety functions of the vehicle. Such a verification of the battery also makes it possible to switch to "cruising" mode at high speed of the vehicle and thus to further reduce the discharges of pollutant gases. Advantageously, the method does not require additional equipment in the vehicle, which limits the cost and bulk.

The term "cruising mode" of the vehicle means a mode of operation of the vehicle during which the vehicle is traveling with the engine stopped and clutch open.

Advantageously, the motor vehicle comprising a capacitor connected in series with the battery by an initially open switch, the test step comprises: - a substep of closing said switch during a predetermined time interval, and - a sub measurement step during the predetermined time interval of the value of the voltage across the battery and the value of the current flowing through the starting device.

Advantageously, the stopping of the thermal engine is allowed if, during the entire predetermined time interval, the value of the measured voltage is greater than a predetermined voltage threshold and the value of the measured current is less than a threshold of predetermined current.

Advantageously, the predetermined voltage threshold is of the order of 11.7 volts.

Advantageously, the predetermined current threshold is of the order of 10 amperes.

Advantageously, the test step comprises a substep of opening the switch at the end of the predetermined time interval.

[0018] Advantageously, the predetermined time interval is of the order of 0.5 s.

Advantageously, the motor vehicle comprising a second switch connected in parallel with the switch and the capacitor, the second switch being initially closed, the test step comprises a sub-step of opening said second switch during the predetermined time interval.

The invention also relates to a motor vehicle comprising a heat engine, a starting member of said engine, a feed battery of said starting member and a computer configured to implement the method as described above.

Other features and advantages of the invention will appear on reading the detailed description of the embodiments of the invention, given by way of example only, and with reference to the drawings which show: FIG. 1 , a simplified circuit diagram of a motor vehicle, according to the invention, comprising a system for testing the vehicle battery. • Figure 2, test results curves by the system of Figure 1.

In what follows, the described embodiments focus more particularly on an implementation of the invention within a motor vehicle. However, any implementation in a different context, in particular in any type of vehicle, is also covered by the present invention.

A motor vehicle comprises electrical equipment and a system for supplying electrical energy to said electrical equipment.

Electrical equipment are modules of the motor vehicle that are adapted to perform different actions. Some electrical equipment is necessary for the proper functioning of the vehicle and are said to be safe, including the brake system, the steering system, the airbag system, etc. Other electrical equipment is not essential to allow the normal operation of the vehicle. These are called "comfort", such as heated seats, the heating of the cabin, etc. The electrical equipment is powered by an electrical voltage allowing the operation of the various electrical equipment.

The power system is adapted to supply the various electrical equipment with electrical energy. The power system provides an electrical voltage adapted to power the electrical equipment so as to allow optimal operation of the latter. To do this, the power system includes an electrical energy storage module and a power generation module.

The storage module is used to power the electrical equipment activated by the electrical energy stored by said storage module. The storage module comprises, for example, at least one electrochemical energy storage system, such as a battery B.

The production module produces electrical energy during the use of the vehicle. The production module can also produce electrical energy to store it in the storage module to recharge it. The production module includes, for example, an alternator.

Thus, the stored energy and the energy produced can power the electrical equipment.

According to the embodiment illustrated in FIG. 1, the motor vehicle comprises an RDB onboard network, an alternator-starter AD and a battery B for supplying electrical energy to the RDB onboard network and the alternator. AD starter.

The RDB onboard network comprises a plurality of electrical equipment, including safe electrical equipment. The RDB onboard network is connected to the terminals of the battery B in order to be supplied with electrical energy.

The alternator-starter AD is a rotating machine incorporating elements of electrical engineering, power electronics and control electronics. The alternator-starter AD can provide a mechanical torque for driving the engine of the vehicle during a request for starting said engine and supply energy to the RDB onboard network when the engine is started. Such an alternator-starter AD thus comprises an alternator function and a starter function. The starter is a starting member of the engine of the motor vehicle. In other words, the starter is supplied with electrical energy to start the engine. Such a starter comprises in particular an electric motor rotating the shaft of the engine to allow the latter to start. The alternator is an electrical equipment producing electrical energy during the use of the vehicle under the effect of the rotation of the engine. Also, the alternator-starter AD is connected to the terminals of the battery B.

Still referring to Figure 1, the vehicle further comprises a test system 10 connected to a terminal of the battery B to test the capacity of the latter to provide the electrical energy required for the restart of the heat engine. case of arrest of the latter.

The test system 10 comprises a first switch K1 and a second switch K2 connected in parallel. A capacitor C is connected in series with the second switch K2.

The switches K1, K2 are controlled by switching. In other words, when the first switch K1 is open, the second switch K2 is closed, and when the first switch K1 is closed, the second switch K2 is open.

When the first switch K1 is closed, the battery B supplies the RDB on-board electrical energy network and the alternator AD-starter. In normal operation of the vehicle, the first switch K1 is closed.

When the second switch K2 is closed (and therefore the first switch K1 is open simultaneously), the capacitor C and the battery B are in series. Only the battery B and the capacitor C feed the RDB onboard network due to the value of the voltage obtained by their series setting which is greater than that delivered by the alternator for a setpoint of the order of 14 V, this which causes a peak in current draw of the battery B. The switch K2 is closed during a test phase of the battery B.

Advantageously, the capacitance C is sized to simulate the current call due to the start of the engine by the alternator-starter AD. The test system 10 thus makes it possible to diagnose the battery B in order to determine whether the latter is able to power the starter in order to start the heat engine.

Such a start of the engine comes at the end of cruise mode, also called "cruise" of the vehicle. During such a mode "cruise", the engine is stopped to reduce the discharge of polluting gases. The battery B must then be tested before stopping the engine to check its ability to power the starter and thus restart the engine.

It will now be presented the method according to the invention for authorizing the stopping of the vehicle engine with reference to FIG. 2.

When activating the "cruise" mode, in particular during a deceleration phase of the vehicle, a vehicle computer receives a request from the cut-off driver of the engine.

The regulating setpoint of the voltage imposed on the edge network is preferably of the order of 13.5V.

The first switch K1 is then open and the second switch K2 is closed simultaneously, at a first time T1 to test the battery B.

The capacitor C and the battery B to be tested supply in series the RDB onboard network, previously powered by the alternator. The value of the voltage obtained by the series setting of the capacitor C and the battery B being greater than the value of the voltage delivered by the alternator, the alternator only delivers a current close to 0 A, or even zero : The battery B discharges, creating a current draw on the battery B to power the RDB onboard network.

As illustrated in Figure 2, when closing the switch K2, the voltage UB across the battery B decreases due to the current call.

At the end of the test, the second switch K2 is open at a second time T2 and the first switch K1 is open. The capacitor C is thus connected to the battery B between the first time T1 and the second time T2 during a test duration ΔΤ of the battery B. Preferably, the test duration ΔΤ is of the order of 0.5 s.

During the test of the battery B, the value of the battery voltage UB is compared with a minimum threshold Smin of voltage and the value of the current IAI passing through the alternator-starter AD is compared to a maximum current threshold to Diag diagnosis of the capacity of the battery B to provide the electrical power necessary to start the engine. In the example of FIG. 2, the minimum voltage threshold Smin is of the order of 11.7 V and the maximum current threshold is of the order of 10 A.

The diagnosis Diag has two states: a high state allowing the stopping of the engine, and a low state prohibiting the stopping of the engine.

During the test of the battery B, if the value of the battery voltage UB is greater than the minimum voltage threshold Smin and if the value of the current Ia crossing the alternator-starter AD is less than the maximum current threshold, the established diagnosis Diag is in the high state. Stopping the engine and launching cruise mode at time T2 are then allowed.

During the test of the battery B, if the value of the battery voltage UB falls below the minimum voltage threshold Smin and / or if the value of the current Ia crossing the alternator-starter AD goes above the threshold current limit, the state of the diagnosis Diag goes low, as shown in Figure 2 at time T3, which prohibits the shutdown of the engine and then prevents the launch of cruise mode.

With the method according to the invention, the ability of the battery to restart the engine end of "cruise" mode is verified before stopping the engine, which reduces the risk of not restarting the engine to the end of the "cruise" mode and thus allows to start the "cruise" mode when the vehicle is traveling at a high speed, especially greater than 20 km / h. The launch of cruise mode at high speed reduces the emission of polluting gases emitted by the engine.

In addition, the verification of the battery B ensures the proper operation of safe electrical equipment, such as brakes, steering and / or airbags, during the vehicle traffic mode "cruise".

Claims (9)

Claims: 1. A method for authorizing the stopping of the engine of a motor vehicle, prior to a circulating mode of said motor vehicle with the engine stopped, said vehicle comprising a starting member (AD) of the engine and at least a battery (B) for supplying electrical power to said starting member (AD), the method comprising: - a step of receiving a stop command of the heat engine, - a step of testing the capacity of the battery (B) supplying the starting member (AD), and - a step of authorizing the stopping of the heat engine if the battery (B) is able to feed the starting member (AD) in order to start the thermal motor. 2. Method according to claim 1, wherein, the motor vehicle comprising a capacitor (C) connected in series to the battery (B) by a switch (K2) initially open, the test step comprises: - a substep closing said switch (K2) during a predetermined time interval (ΔΤ), and - a measurement sub-step during the predetermined time interval (ΔΤ) of the value of the voltage (UB) at the terminals of the battery ( B) and the value of the current (Iad) passing through the starting member (AD). 3. Method according to the preceding claim, wherein stopping the heat engine is allowed if, throughout the predetermined time interval (ΔΤ), the value of the voltage (UB) measured is greater than a threshold (Smin) of predetermined voltage and the measured current value (IAd) is below a predetermined current threshold. 4. Method according to the preceding claim, wherein the predetermined voltage threshold (Smin) is of the order 11.7 V. 5. Method according to one of claims 3 to 4, wherein the predetermined current threshold (Smin) is of the order of 10 A. 6. Method according to one of claims 2 to 5, wherein the test step comprises a substep of opening the switch (K2) at the end of the predetermined time interval (ΔΤ). 7. Method according to one of claims 2 to 6, wherein the predetermined time interval (ΔΤ) is of the order of 0.5 s. 8. Method according to one of claims 2 to 7, wherein, the motor vehicle comprising a second switch (K1) connected in parallel to the switch (K2) and the capacitor (C), the second switch (K1). initially being closed, the test step comprises a substep of opening said second switch (K1) during the predetermined time interval (ΔΤ). 9. Motor vehicle comprising a heat engine, a starting member (AD) of said heat engine, a supply battery (B) of said starting member (AD) and a computer configured to implement the method according to one of the preceding claims.