FR3026992A1 - METHOD FOR CONTROLLING A BATTERY CHARGING DEVICE, IN THE IDLING MOTOR REGIME - Google Patents

Abstract

The subject of the present invention is a method of controlling a battery charging device driven by a heat engine in a vehicle, during a idling engine speed (Nidle), the battery charging device being able to supply a nominal power. at a normal engine speed (Nidle_N) predetermined idle, characterized in that it comprises the following steps: • Define a first threshold of maximum torque (Calt_Max1) consumed per battery charging device, admissible during said engine speed (Nidle) at idle, • During the said predetermined normal idle engine speed, if the torque consumed (Calt) by the battery charging device reaches the first peak torque threshold (Calt_Max1) consumed, then lower the electric power supplied by the charging device below said rated power value, while maintaining a set voltage (Ualt) of the bat charge device to a value greater than a battery discharge voltage, and • Simultaneously maintain said engine idle speed (Nidle) at said predetermined normal engine speed (Nidle_N).

Description

The present invention relates to a method for controlling a battery charging device driven by a heat engine in a vehicle, during an idle engine speed, the battery charging device being able to supply a nominal power to a motor. normal engine speed predetermined idle. An idle engine speed is referred to as a particular mode of operation of the engine in which the engine speed is turned to a minimum to avoid stalling, corresponding to a raised-foot accelerator and the transmission of the uncommitted vehicle. In this mode of operation, the motor generates enough power to turn smoothly and properly operate the auxiliaries that depend on it (such as the water pump, the alternator, etc.). For a particular vehicle, the idle engine speed is usually between 600 and 1000 rpm. The prior art teaches such a method of controlling a battery charging device, of increasing the predetermined normal idle engine speed to a given maximum idle speed level, when the load of the charging device 15 of the battery, for example an alternator, reaches a threshold of maximum permissible torque at the predetermined normal engine speed of idling. Such a maximum torque threshold is reached most of the time at the idle speed, for example by the activation of an auxiliary by the engine control unit or by the driver, and in any case by controlling the load of the engine. the battery which is instructed to always maintain the battery at its maximum state of charge, polarization phase included. Thus, the idling engine speed increases, the torque produced by the engine increases, and the available torque increases to avoid the risk of stalling. The alternator always using the same mechanical power to realize the needs of the electrical network. If the alternator load decreases during the maximum idle speed, that is, the engine torque used by the alternator to produce the electrical energy used by the onboard system decreases, until a low limit or minimum allowable load threshold for the alternator at the maximum idle speed, then stopping of the maximum idle speed is controlled by the engine control unit, thereby reducing the idle engine speed to the predetermined normal engine speed slow motion.

Such a method of controlling a battery charging device, according to the prior art, is for example shown in FIGS. 1A and 1B, and will be described in detail later. This method according to the prior art has drawbacks, and in particular the fact that the idling speed is always increased to its maximum allowed, even in the case where such an increase is not justified. Fuel consumption is thus increased at idle speed in a sometimes unnecessary way. The present invention proposes to overcome this disadvantage. More specifically, the invention relates to a method for controlling a battery charging device driven by a heat engine in a vehicle during an idle engine speed, the battery charging device being able to provide a nominal power. at a predetermined normal idle engine speed, characterized in that it comprises the following steps: - Define a first threshold of maximum torque consumed per battery charging device, admissible during said engine idling speed, - During said normal engine speed predetermined amount of idle, if the torque consumed by the battery charging device reaches said first maximum consumed torque threshold, then lowering the electric power supplied by the battery charging device below said rated power value, while maintaining a target voltage of the battery charging device to a value greater than a discharge voltage and simultaneously maintaining said idle engine speed at said predetermined normal idle engine speed. According to the invention, when the torque consumed by the charging device exceeds the maximum permissible torque threshold consumed, the operating point of the charging device is shifted, for example by reducing its target voltage, so that its consumed torque decreases. . The idle speed is thus not changed, the battery charges less, but does not discharge because the voltage of the charging device is maintained above the discharge voltage of the battery. Fuel consumption at idle speed is thus reduced in comparison with the prior art. From a system point of view, the device for charging the battery, for example an alternator, delivers more current than the auxiliaries receive, and the additional current goes into the battery: according to the invention, this is this extra current will be limited. The efficiency of a heat engine being less good at idle speed, the invention makes it possible to avoid recharging the battery under poor performance conditions. According to an advantageous characteristic, said first threshold of maximum torque consumed by the battery charging device will be defined from a percentage of the maximum torque for the maximum theoretical power that the battery charging device is capable of providing, for example 90 %, or from a threshold on the available engine torque preventing any risk of stalling or jerking of the engine.

According to an advantageous characteristic, the method according to the invention further comprises the following steps: During said predetermined normal idle engine speed, if after lowering the electric power supplied by the battery charging device below said nominal power value, the torque consumed by the battery charging device reaches a second maximum torque threshold consumed, then increasing the idle engine speed above the predetermined normal idle engine speed, and - setting a first threshold of minimum torque consumed by the battery charging device 10 during an increasing idling engine speed; - during said increase in idle engine speed, if the torque consumed by the battery charging device reaches said first threshold of minimal torque consumed by the battery charging device, then stop the increase in the engine idle speed p to stabilize it at an idle engine speed increased to a minimum. This feature makes it possible to overcome a lack of activation of the first measurement according to the invention to lower the power supplied by the charging device. If this first step is not enough, then the idle speed is increased to an increased speed optimized according to the need. As soon as the torque consumed decreasing sufficiently due to the increase in the speed reaches the first threshold of minimum torque consumed, the idle speed increase is stopped in order to stabilize it at an idle speed, constant, increased to a minimum. of need. According to the invention, the idle speed is thus increased only if necessary, and for less time than according to the state of the art described above. The battery charges less, but does not discharge. Fuel consumption is thus reduced. According to an advantageous characteristic, said first minimum torque threshold consumed will be defined from a percentage of the maximum torque for the maximum theoretical power that the battery charging device is capable of providing, for example 85%, or from a threshold on the available engine torque preventing any risk of stalling or jerking of the engine. According to an advantageous characteristic, said second threshold of maximum torque consumed is greater than said first threshold of maximum torque consumed. According to an advantageous characteristic, the method according to the invention furthermore comprises the following step: - Define a second minimum torque threshold consumed by the battery charging device during an idle engine revs increased to a minimum, 3026992 4 - During said idle engine revs increased to a minimum, if the torque consumed by the battery charging device reaches said second minimum torque threshold consumed by the battery charging device, then lowering the engine idle speed increased to a minimum, until normal engine speed 5 predetermined idle. This feature maximizes the maintenance of the increased idle speed to a minimum, for the time just needed, as needed. The fuel consumption due to the increase of the idling speed is thus minimized.

According to an advantageous characteristic, said second minimum torque threshold consumed will be defined from a percentage of the maximum torque for the maximum theoretical power that the battery charging device is capable of providing, for example 90%, or from a threshold on the available engine torque preventing any risk of stalling or jerking of the engine.

According to an advantageous characteristic, said first minimum torque threshold consumed by the battery charging device is greater than said second minimum torque threshold consumed by the battery charging device. According to an advantageous characteristic, the method according to the invention further comprises the following steps: defining a third threshold of minimum torque consumed by the battery charging device during said predetermined normal idling engine speed; during said normal engine speed; predetermined amount of idle, if the torque consumed by the battery charging device reaches the third minimum torque threshold, then increasing the power supplied by the battery charging device to the rated power value than the charging device of the battery charging device. battery is able to provide the predetermined normal engine idling speed. This characteristic amounts to suppressing the lowering of power applied to the charging device during the idling speed when the first threshold of maximum torque consumed, according to the invention, is reached. The charging device thus regains its nominal power which it is capable of supplying at the predetermined normal engine speed of idling. According to an advantageous characteristic, said third minimum torque threshold consumed will be defined from a percentage of the maximum torque for the maximum theoretical power that the battery charging device is capable of providing, for example 85%, or from a threshold on the available engine torque preventing any risk of stalling or jerking of the engine.

According to an advantageous characteristic, said second and third thresholds of minimum torque consumed by the battery charging device are equal or substantially equal. According to an advantageous characteristic, the lowering of the electric power supplied by the battery charging device is obtained by means of a lowering of its target voltage. The invention also relates to a control system for a battery charging device driven by a heat engine in a vehicle, during an idling engine speed, said vehicle being provided with a battery current sensor, a control unit 10 (ECU), and control means of the charging device, the control system being characterized in that it comprises means for implementing a method according to the invention as defined above. A method according to the invention can simply be implemented by means of software implemented in the engine control unit thus minimizing the cost of applying such a method.

Further features and advantages will be apparent from the following reading of exemplary embodiments of a method of driving a battery charger device driven by a heat engine in a vehicle during idle engine speed. according to the invention, accompanied by the appended drawings, examples given by way of nonlimiting illustration, in which: FIG. 1A is a representative diagram of the curves of the power supplied by the alternator and of the torque consumed by the latter, and engine idling speed according to an example of the method according to the prior art of driving a battery charging device driven by a heat engine in a vehicle during idling engine speed; FIG. 1B is a flow diagram of the process according to the prior art in accordance with FIG. FIG. 2 is a representative diagram of the evolution of certain parameters of the engine during idling engine speed, according to a first example of a method according to the invention for controlling a battery charging device driven by a heat engine. in a vehicle; FIG. 3 is a representative diagram of the evolution of certain parameters of the engine during idling engine speed, according to a second example of a method according to the invention for controlling a battery charging device driven by a heat engine in a vehicle ; FIG. 4 is a flow diagram of the first and second examples of a method according to the invention, in accordance with FIGS. 2 and 3.

FIG. 1A represents, at a Nid idle speed of a heat engine, a time scale t on the abscissa, and several scales on the ordinate, each corresponding to the respective parameter represented, namely the evolution of the Nid idle speed in revolutions. per minute, the evolution of the Calt torque consumed on the engine by the load device, measured in torque equivalent in newtons-meters, the evolution of the electrical power Pait supplied by the alternator own to the charge of the battery and to the electrical consumers measured in watts, the evolution of the voltage Ubatt of the battery in volts. In Figure 1A, the charging device is for example an alternator. The Calt couple is divided into two parts, Cbat representing the share of 10 torque consumed by the alternator own to the charge of the battery, and Caux the share of torque consumed by the alternator specific to the power supply of the electrical consumers. The Cbat pair is related to the energy consumed by the battery at idle speed. When the battery is fully charged, it always draws power to keep its charge to a maximum.

For illustrative purposes, FIG. 1A shows the evolutions of the Pbat and Paux components of the powers provided by the alternator necessary respectively for recharging the battery and for powering the electrical auxiliaries. FIG. 1A also shows: A maximum torque threshold Calt Max of the alternator consumed on the engine, which is admissible at the normal engine speed Nidle N predetermined idle, and a minimum torque threshold Calt Min of the engine. alternator consumed on the engine, eligible for maximum idle speed Nidie Max. As shown in FIG. 1A, the engine rotates at normal engine speed No predetermined idle speed which is programmed by the engine control unit, for example 800 rpm, then at time t1, the torque Calt of the alternator consumed on the engine reaches the threshold of maximum torque Calt Max consumed, for example by the activation of a new electrical consumer, which triggers on the part of the engine control unit the control of the increase the engine speed Nide idle to reach gradually but in a single increment the maximum engine speed Nide Max 30 predetermined idle, for example 1000 rpm, at the moment The maximum speed Nidle Max idle then remains constant until the Calt torque of the alternator consumed on the clean engine at the charge of the battery and at the electrical consumers reaches the minimum torque threshold Calt Min consumed by the alternator admissible at the maximum engine speed Ni Idle die Max, which happens at the instant t2. At this time t2, the engine control unit then controls the deletion of the maximum Nidie Max idle speed, and the engine thus returns to the normal engine speed Nidle N predetermined idle. Between times t1 and t2, we note in Figure 1A that the 3026992 7 torque Calt consumption decreases from time t1 due to the increase in Nide idle engine speed to stabilize at the moment t'l The maximum idle speed Nidie Max, where this torque becomes constant up to the moment t ", where a power consumed by the auxiliaries decreases then again causes a decrease in the Calt torque. At time t2, the torque Calt increases because the engine speed Nide idle decreases.Ubat voltage of the battery is kept constant by the voltage imposed by the alternator throughout the idle speed, as shown in Figure 1A. Prior art as described, the idle speed is always increased to its maximum allowed or predetermined, even if the state of charge of the battery does not justify it.The logic diagram shown in Figure 1B illustrates the example described of method of the prior art according to Figure 1A, which thus comprises the following steps: - Step 1: the engine rotates at normal engine speed Nidle N predetermined idle. In a conventional manner, the alternator provides at this engine speed Nidie N 15 idling a given power value according to its operating diagram taken at the voltage Ubatt that is assimilated in the example of the prior art described in the voltage the alternator, at a given temperature and for a given output current; - Step 2: when the current Calt current of the alternator consumed on the engine 20 during the normal engine speed Nidle N predetermined idle reaches the maximum torque threshold Calt Max permissible consumed on the engine; then - Step 3: the normal engine speed Nidle N predetermined idle is increased by a given number of revolutions, to reach the maximum engine speed Nidie Max idle; Step 4: When the current Calt of the alternator consumed on the engine during this maximum engine speed Nide Max idle decreases to reach the minimum torque threshold Calt Min allowable, then the engine control unit suppresses the increase of idling speed, and idle idle engine speed accordingly decreases to normal engine idle Nide N predetermined idle. A first exemplary embodiment of a method according to the invention will now be described with the help of FIG. 2. For this example, the references of elements identical to those used for the description of the example according to FIG. prior art will be reused. The charging device of the battery is for example an alternator. The vehicle is equipped in a known manner with a battery current sensor, a motor control unit, and alternator control means, for example with voltage or pulse width modulation (PWM). Pulse Width Modulation "in 3026992 8 English) by the engine control unit. The battery current sensor allows the motor control unit to determine whether the battery is in a charging or discharging state via the battery current sense. The engine control unit also has, in a known manner, a means for evaluating the torque consumed by the alternator.

FIG. 2 represents, at an idle speed of the engine, a time scale t in abscissa in seconds, and several scales in ordinate each corresponding to the respective parameter represented, namely the evolution of the Nidle idle speed in revolutions per minute. minute, the evolution of the electrical power Palt supplied by the alternator breaking down into two parts, namely Pbat the proper share of the charge of the battery and Paux the share of electric consumers, measured in Watts, the evolution the Calt torque of the alternator consumed on the engine, broken down into two parts, namely Cbat the share of torque consumed by the alternator own battery charge, and Caux the share of torque consumed by the own alternator to the power supply of electrical consumers (Calt = Cbat + Caux). Torque quantities 15 are measured in torque equivalent in newtons-meters. FIG. 2 also represents the evolution of the voltage setpoint of the Liait alternator in volts, which in the example is assimilated substantially to the voltage Ubatt of the battery. The share Cbat of torque consumed by the alternator own to the charge of the battery is directly connected to the energy consumed by the battery at idle speed.

FIG. 2 furthermore shows: - the normal voltage Ualt N setpoint of the alternator during the normal engine speed Nide N predetermined idle, - the minimum voltage Ualt Min setpoint of the alternator during the engine speed normal Nielle N predetermined idle, 25 - A first threshold of maximum torque Calt Maxi allowable consumed by the alternator at normal engine speed No predetermined N idling, and - A third threshold of minimum torque Calt min3 eligible consumed by the alternator, operating at its minimum voltage Ualt Min. This third minimum torque threshold Calt min3 may represent, for example, 60% of the maximum theoretical torque produced by the alternator at the Nidle N. engine idling speed. As shown in FIG. 2, according to the invention, the engine runs at normal engine speed Nidle N predetermined idle speed programmed by the engine control unit, for example 800 rpm, and the alternator provides a rated power at this normal engine speed Nidle N predetermined idle with a set voltage Ualt N 35 normal, for example 14 volts. This rated power value that the alternator is able to provide at a normal engine speed Nidle N predetermined idle is recorded in the engine control unit. The first threshold of maximum torque Calt Maxi consumed by the alternator, permissible during idle engine speed N'ale N, was recorded in the engine control unit. This first threshold Calt maxi is determined as being the maximum allowable torque limit taken by the alternator on the engine which respects the stability of the idle speed, that is to say which limits the engine speed oscillations, for example tolerating maximum oscillations of 30 rpm. Under these conditions, at time t1, the Calt torque consumed by the alternator used to power the electrical auxiliaries and the recharging of the battery reaches in the example the first threshold of maximum torque Calt max. Such a limit is reached, for example, by the activation of a new electrical consumer, for example headlights or wipers. The achievement of the first maximum torque threshold Calt Maxi then triggers on the part of the engine control unit the control of a lowering of the electric power supplied by the alternator, below the nominal power value, without request from the alternator control strategy to change the idle speed value. This lowering of the electrical power supplied by the alternator is for example obtained by advantageously decreasing the reference voltage Uait of the alternator while maintaining this reference voltage Uait at a value higher than a battery discharge voltage. For this purpose, the engine control unit measures the battery current by means of the battery current sensor, and lowers the alternator setpoint so as to reduce the charging current of the battery without canceling it in order to guarantee avoid a discharge of the battery (reversal of the direction of the battery current). It can be considered as an example that a normally charged battery corresponds to a state of charge of the order of 70% of its maximum charge. Insofar as the alternator 25 would be driven by the motor control unit as a percentage of operation, via a pulse width modulable PWM signal (PWM), the decrease of the set voltage Uait of the alternator would be converted. in an equivalent cyclic ratio of the PWM signal, according to any known means. The generator setpoint voltage is for example reduced to a minimum setpoint voltage Ualt Min of between 11.8 volts and 13 volts which is a voltage sufficient to maintain the charge of the battery at a normal value, of 70% (3/0) of the maximum charge of the battery, and sufficient to supply correctly all the electrical auxiliaries connected to the alternator, remember that this minimum nominal voltage Ualt Min is determined by the engine control unit by means of of the battery current sensor so that there is a minimum charging current to the battery necessary and sufficient to avoid a discharge of the latter.The minimum setpoint voltage Ualt Min preferably remains slightly above the range of 3026992 10 battery bias voltage to avoid discharge of the battery The setpoint decrease of the alternator voltage shifts its operating point by correspondingly decreasing its output current, at a constant speed of rotation, and thus decreasing its load. This reduction in voltage at a constant speed of the alternator 5 causes a reduction in the engine torque consumed by the alternator Calt, as shown in FIG. 2. This amounts to minimizing the Cbat component of the consumed torque. The minimum nominal voltage Liait Min then remains maintained until the Calt torque consumed by the alternator reaches, if necessary, the third threshold of minimum torque Calt min3 acceptable for the alternator according to the minimum setpoint voltage Uait min, the idle speed being always set at the normal engine speed Nidle N predetermined idle, which occurs at time t2. This torque reaches the threshold of minimum torque Calt min3 admissible for example when one or more electric consumers consume less electrical energy. At this time t2, the engine control unit then controls the increase of the setpoint voltage Ualt of the alternator to the nominal voltage value Liait N normal, the engine still being maintained at the normal engine speed Nide N predetermined idle, as shown in Figure 2. The Cbat couple consumed by the alternator own battery charge after time t2 can grow as shown, still during the idle speed, and if the overall consummated torque Calt 20 reaches the first maximum torque threshold Calt Maxi, the alternator setpoint voltage can be lowered again, while maintaining the engine idle speed at its normal value Nidle N. Thus, during the entire phase of engine idle, the engine speed will have been maintained at normal engine speed Nidle N predetermined idle, thus achieving a fuel economy. The battery charges less, but does not discharge. A second exemplary embodiment of a method according to the invention will now be described with the help of FIG. 3. The example of FIG. 3 is in a particular case of the example of FIG. , and includes an increase in engine idle speed. Also, the elements taken from this FIG. 2 have the same references 30 in FIG. 3. FIG. 3 thus takes up the same abscissa axis, the same ordinate axis, and the same motor parameters represented. Reference will be made to the description made above of FIG. 2 for these elements. Since the time references on the abscissa axis are chronological, the event occurring at time t6 in FIG. 3 corresponds to the event occurring at time t2 in FIG. The following details are shown on the abscissa of FIG. 3, occurring at times t2, t3, t4, and t5. FIG. 3 furthermore shows: A second threshold of maximum torque Calt Max2 consumed by the alternator, which is eligible to request a request for an increase in idle idle engine speed, which is recorded in the idle unit. engine control; this second maximum torque threshold Calt Max2 is defined in such a way that the increase of the idling speed is necessary and sufficient as a function of the need, and may represent, for example, 90% of the maximum theoretical torque produced by the alternator at this Nide idle engine rotation speed; this second threshold of maximum torque Calt Max25 if it is not respected, may reduce the share of the torque consumed by the alternator for the minimum recharge of the battery, and cause, therefore, 10 a battery discharge; - A first Calt Minl minimum torque threshold consumed by the alternator, which is admissible to stop the increase in idle idle engine speed, which is stored in the engine control unit; this first threshold Calt Uni is defined in such a way that the increase of the idling speed is necessary and sufficient according to the need, and may represent, for example, 85% of the maximum theoretical torque produced by the alternator at this Nide regime. engine rotation; - A second Calt Ming minimum torque threshold consumed by the alternator, eligible to start the suppression of the idle idle engine speed increase, for a return of the idle speed Nide to the normal engine speed Nidle N 20 predetermined idle, which is registered in the engine control unit; this second threshold Calt Min2 is defined in such a way that the suppression of the increase of the idling speed is necessary and sufficient according to the need, and can represent, for example, 80% of the maximum theoretical torque produced by the alternator at this engine idling speed Nide idle; 25 - As in the example of FIG. 2, the third minimum torque threshold Calt Min3 of the alternator, which is admissible for a return of the control command of the alternator to its predetermined value of idling, which is also recorded in the engine control unit; this third threshold Calt min3 may represent, for example, 60% of the maximum theoretical torque produced by the alternator at this idling speed. As for the example of FIG. 2, at time t1, the Calt pair of the alternator specific to the charge of the battery and the power supply of the electrical auxiliaries reaches the first threshold of maximum torque Calt Maxi, which triggers on the part of the engine control unit the control of a lowering of the power supplied by the alternator below the nominal power value, for example by advantageously decreasing the reference voltage Uait of the alternator while maintaining this setpoint voltage Uait at a value higher than a battery discharge voltage.

In contrast to FIG. 2, in the example of FIG. 3, from the time t1 when the alternator setpoint voltage has been lowered, the torque consumed by the alternator decreases and then Increases successively, for example by activating new electrical consumers, or increasing power consumption of existing activated consumers. At the successive moment t2 at t1, the torque C consumed by the alternator reaches a second threshold of maximum torque Calt Max2 consumed, preferably set higher than the first threshold of maximum torque Calt Max1 consumed, as represented in FIG. at this time t2, the idle idle engine speed is then increased above the predetermined idle Nide N normal engine speed. The increase in idle idle engine speed shifts the operating point of the alternator and thus reduces the engine torque that it consumes at constant output current. The torque consumed by the alternator Calt decreases, as represented between times t2 and t3. When the torque consumed by the alternator Calt reaches the first threshold of torque consumed minimum 15 Calt Minl by the alternator, admissible to stop the increase of idle idle engine speed, which is achieved at time t3 in the figure , the increase in the idle speed is then stopped and the engine speed N, idle die is stabilized at idling speed Nide Inc. increased to a minimum. The torque consumed by the alternator Calt may decrease from time t3, for example if the overall power consumption decreases, as shown in the example between t3 and t4, to reach at time t4 the second threshold of torque consumed minimum Calt Min2 by the alternator, eligible for a return of idle speed Nide at normal engine speed Nidle N predetermined idle. At time t4, the engine control unit therefore commands a decrease in engine speed N, idle die, of idle speed Nidle Inc engine speed to at least the predetermined normal engine speed Nidle N of slowed as shown. This reduction in speed is shown in FIG. 3 between times t4 and t5. At time t5, the engine idle speed returns to its predetermined Nide N value idle. After the time t4, the idle engine speed gradually decreases, and the torque consumed Calt by the alternator evolves according to the need of all electrical consumers. If the torque consumed by the alternator Calt increases to reach (not shown) a second time for example the second maximum torque threshold Calt Max2 consumed, the process resumes as from time t2, that is to say that the idle is again increased according to the need, stabilized, then brought back to its normal value Nide N. If after the time t5, the idle speed reaches the third threshold of torque consumed minimum Calt min3 by the alternator during the normal engine speed Nidle N 3026992 13 predetermined idle, and the alternator operating at its minimum voltage linked Min setpoint, then the engine control unit controls the increase of the power supplied by the alternator to the nominal power value that the battery charging device is able to provide the normal engine speed Nidle N predetermined 5 idle. The third minimum consumed torque threshold Calt m, n3 acceptable by the alternator for this example is the same as for the example of FIG. 2. In FIG. 3, this third minimum consumed torque threshold Calt Min3 is reached at the moment t6 as shown. The engine control unit then increases at time t6 the power supplied by the alternator to the rated power value 10 that the battery charging device is able to provide the normal engine speed Nielle N predetermined idle. Note that in this example, the idle speed is changed only if it is necessary, and less than in the state of the art. Fuel consumption is thus reduced. Preferably, the first minimum consumed torque threshold Calt mini by the alternator is greater than the second minimum consumed torque threshold Calt Ming by the alternator. The second Calt Min2 is greater than the third threshold Calt Min3- The logic diagram shown in FIG. 4 illustrates a method combining the two examples described of the method according to the invention illustrated with FIGS. 2 and 3, which thus comprises the following steps: Step 10: The engine is running at normal engine speed Nidle N predetermined idle. In a conventional manner, the alternator provides at this idle Nielle N engine speed a nominal power value, at the normal setpoint voltage Uait N, at a given temperature and for a given output current of the given alternator; Step 20: when the torque consumed current Calt by the alternator during the normal engine speed Nide N predetermined idle reaches the first maximum torque threshold Calt Maxi consumed allowable, then - Step 30: lower the power supplied by the alternator below the nominal power value, for example by a lowering of the setpoint voltage of the alternator of the normal voltage Uait N of setpoint to the minimum voltage Ualt Min of setpoint, while maintaining a set voltage Liait of the alternator to a value greater than a battery discharge voltage, and simultaneously maintain the engine speed N, idle die at normal engine speed Nidle N predetermined idle, 35 - Step 40: when the torque consumed current Calt by l alternator during the normal engine speed Nielle N predetermined idle reaches the second maximum Calt Max2 torque threshold consumed admissible, then 3026992 14 - Step 50 : the normal engine speed Nidle N predetermined idle is increased gradually, - Step 60: when the torque consumed current Calt of the alternator during this increase in engine idle speed reaches the first threshold of torque 5 minimum Calt uni, then the idle speed increase is stopped, and - Step 70: the engine speed N, idle die is stabilized at an engine speed Nidle lnc idle increased to a minimum, - Step 80: when the torque consumed current Calt by the alternator during this engine speed Nidelnc idle increased to minimum reached the second threshold of 10 minimum torque Calt Ming, then the idle speed is reduced to the normal engine speed Nide N predetermined idle, and - Step 41: when the current consumption torque Cait by the alternator reaches the third threshold of minimum torque Cait min3, during the normal engine speed Nidle N predetermined idle, the target voltage Uait of the alt Since the generator is equal to Ualt Min, then - Step 90: Set the setpoint voltage Uait of the alternator to its minimum setpoint voltage Ualt Min during the normal engine speed Nide N predetermined idle. The process examples as described above can be implemented by an alternator control system, during a idle engine speed, comprising an engine control unit (ECU) for the engine control unit. vehicle being provided with a battery current sensor measuring the battery current to enable a determination of the state of charge or discharge of the battery, and adjustable control means of the alternator, for example an alternator Pulse Width Modulation (PWM) control in PWM, the control system comprising means for implementing a method as described in the form of software implemented in the application of the invention. motor control unit.

Claims (10)

REVENDICATIONS1. A method of controlling a battery charging device driven by a heat engine in a vehicle during a idle engine speed (Nidle), the battery charging device being adapted to supply a nominal power at a normal engine speed (Niole N) predetermined idling, characterized in that it comprises the following 5 steps: - Set a first maximum torque threshold (Calt maxi) consumed per battery charging device, admissible during said engine idle speed (Nidle), - During said predetermined normal idle engine speed (Nide N), if the torque consumed (Calt) by the battery charging device reaches said first threshold of maximum torque (Calt max) consumed, then lowering the electrical power supplied by the device for charging the battery below said nominal power value, while maintaining a set voltage (link) of the battery charging device to a higher value at a battery discharge voltage, and 15 - Simultaneously maintain said engine idle speed (Nidle) at said predetermined normal engine speed (Nidle N) idle. The driving method according to claim 1, further comprising the following steps: - During said predetermined idle normal engine speed (Nide N), if after lowering the electric power supplied by the battery charging device below of said nominal power value, the torque consumed (Calt) by the battery charging device reaches a second peak torque threshold (Calt max2) consumed, then increasing the engine idle speed (Nidle) above the normal engine speed predetermined (N, die N) idle, and 25 - Set a first threshold of minimum torque (Calt mini) consumed by the battery charging device during an increasing engine idle speed, - During said increase in engine speed (Nidle ) idle, if the torque (Calt) consumed by the battery charging device reaches said first minimum torque threshold (Calt Min1) consumed by the battery charging device, then stop increasing idle speed (Nidle) to stabilize it at an Inc, engine idle (Nidle) idle increased to a minimum. 3026992 16 3. Control method according to claim 2, wherein said second threshold of maximum torque (Calt max2) consumed is greater than said first threshold of maximum torque (Calt Maxi) consumed. 4. The driving method as claimed in claim 2, further comprising the following step: defining a second minimum torque threshold (Calt Min2) consumed by the battery charging device (1) during a driving speed ( Nidle) idle increased to minimum,, - During said engine idle (Nidle Inc) idle increased to a minimum, if the torque (Calt) consumed by the battery charging device reaches said second threshold of minimal torque (Calt Ming) consumed by the battery charging device, then lowering the engine speed (N, die) from idle to minimum, to the normal engine speed (N, die N) predetermined idle. The driving method according to claim 4, wherein said first minimum torque threshold (Calt Min1) consumed by the battery charging device is greater than said second minimum torque threshold (Calt Min2) consumed by the charging device of the battery charging device. drums. The driving method according to any one of claims 1 to 5, further comprising the following steps: - defining a third minimum torque threshold (Calt min3) consumed by the battery charging device during said normal engine speed (Nide N) predetermined idle, - During said normal engine speed (Niole N) predetermined idle, if the torque consumed (Calt) by the battery charging device reaches the third threshold of minimum torque (Calt Min3), then increase the power provided by the battery charging device to the nominal power value that the battery charging device is capable of supplying the predetermined normal engine speed (Nide N) idle. 7. The driving method according to claim 6 taken in combination with claim 4, wherein said second (Calt Ming) and third (Calt min3) minimum torque thresholds consumed by the battery charging device are equal or substantially equal. The driving method according to any one of claims 1 to 7, wherein the lowering of the electric power supplied by the battery charging device is achieved by lowering its set voltage (Liait). . 3026992 17 9. Control method according to any one of claims 1 to 8, wherein said first threshold of maximum torque (Cali max) consumed by the battery charging device, or said first minimum torque threshold (Cali Minl) consumed, or said second minimum torque threshold (Cali Ming) consumed, or said third minimum torque threshold (Calt min3) consumed will respectively be defined from a percentage of the maximum torque for the maximum theoretical power that the battery charging device is able to provide, or from a threshold on the available engine torque preventing any risk of stalling or jerking of the engine. 10. A control system for a battery charging device driven by a heat engine in a vehicle during idle engine speed, said vehicle being provided with a battery current sensor, an engine control unit. , and control means of the charging device, the control system being characterized in that it comprises means for implementing a method as defined in one of claims 1 to 9.