MONITORING FORWARD LEAPS OF AN ELECTRICALLY POWERED LAND VEHICLE ASSOCIATED WITH DIFFERENT TRAINS

Abstract

A monitoring method is implemented in a land vehicle comprising first and second electric power units delivering first and second motor torques to drive wheels belonging to first and second axles. This method includes a step (10-50) in which the difference between a sum of first and second torques at the wheels, determined as a function of the first and second motor torques delivered, and a setpoint for the total torque to be supplied to the drive wheels is determined. Then, when a value based on this determined difference does not satisfy a chosen forward leap criterion, the operation of one of the first and second electric power units is prohibited, and the other is forced to operate in a degraded mode. Figure 3

Description

Title of the invention: MONITORING THE FORWARD JUMPING OF A LAND VEHICLE WITH ELECTRIC POWER ENGINES ASSOCIATED WITH DIFFERENT TRAINS Technical field of the invention

[0001] The invention relates to land vehicles comprising two electric drive machines and associated respectively with two independent drive wheel assemblies, and more specifically to the monitoring in such vehicles of their forward leaps.

[0002] Herein, "forward leap" means a phenomenon causing a vehicle to move forward or backward more than a predefined distance (typically 50 cm) in less than a predefined time (typically 1.4 seconds) due to a total torque at the drive wheels not desired by the driver and therefore not proportional to the depressor of the accelerator pedal. State of the art

[0003] Certain land vehicles (and for example of the automobile type), include a powertrain (or PMT) comprising at least first and second electric drive machines which, when supplied with electric current by an electric power source (such as a power battery or a fuel cell), deliver respectively first and second motor torques to drive in rotation drive wheels belonging respectively to independent first and second trains.

[0004] This type of vehicle (with two independent drive trains) can operate, in particular, in a four-wheel drive (or AWD (“All Wheels Drive”) mode - all-wheel drive) when its first and second electric drive machines simultaneously provide motor torques.

[0005] In the vehicles described above, it can happen that at the end of a maneuver, the total torque at the drive wheels is strictly greater than what the driver intends and is therefore not proportional to the accelerator pedal depressor. In this situation of combined over-torque at both drive axles, the vehicle lurches forward in its current direction of travel, which can be dangerous because it may then strike an obstacle (object or living being).

[0006] This forward leap problem can result from an insufficient level of precision in the two sensors measuring the respective speeds of the rotors of the first and second electric drive machines, from which the first and second motor torques delivered are determined, and / or from insufficiently precise operation of the first and second electric drive machines. To remedy this, more precise speed sensors and / or first and second electric drive machines with more precise operation could be used, but this would be quite expensive and would therefore significantly increase the cost of the vehicles concerned.

[0007] The invention therefore aims in particular to improve the situation. Presentation of the invention

[0008] In particular, it proposes for this purpose a monitoring method intended to be implemented in a land vehicle and comprising first and second electric drive machines capable of delivering first and second motor torques respectively to drive in rotation drive wheels belonging respectively to first and second trains.

[0009] This monitoring method is characterized by the fact that it includes a step in which a difference is determined between a sum of first and second torques at the wheels, determined respectively as a function of the first and second motor torques delivered, and a setpoint of total torque to be supplied to the drive wheels, then, when a value as a function of this determined difference does not satisfy a chosen forward leap criterion, the operation of one of the first and second electric drive machines is prohibited and the operation of the other of these first and second electric drive machines is imposed in a degraded mode.

[0010] Thanks to the invention, it is now possible to avoid the occurrence of a forward leap, without the need to use more precise speed sensors and / or first and second electric drive machines with more precise operations, which makes it possible not only to avoid the vehicle hitting an obstacle, but also to significantly increase the cost of the vehicle.

[0011] The monitoring method according to the invention may include other features which can be taken separately or in combination, and in particular:

[0012] - in its step, the forward leap criterion can be chosen according to a duration during which the determined difference has exceeded a first chosen threshold;

[0013] - in the presence of the first option, in its step, the forward leap criterion can be a point, defined by the determined difference and the duration for which this determined difference exceeded the first threshold, located below a curve of evolution of a torque difference as a function of a duration of exceeding the threshold;

[0014] - also in the presence of the first option, in its step, the first threshold chosen can be between 0 Nm and 5 Nm;

[0015] - in its degraded mode stage, it may consist of delivering a motor torque which is capable of causing the vehicle to move at a speed lower than a second chosen threshold;

[0016] - in the presence of the last option, in its step, the second threshold chosen can be between 10 km / h and 20 km / h;

[0017] - in its step one can also perform in the vehicle at least one chosen action including an alert from a vehicle driver by means of a warning light on the vehicle and / or a text message and / or an audible message indicating a need for vehicle check, and a recording of at least one fault code representative of a problem with the vehicle's forward leap.

[0018] The invention also proposes a computer program product comprising a set of instructions which, when executed by processing means, is suitable for implementing a monitoring method of the type presented above, in a land vehicle and comprising first and second electric drive machines suitable for delivering first and second motor torques respectively to drive wheels belonging respectively to first and second trains, to monitor forward leaps of the vehicle.

[0019] The invention also proposes a monitoring device intended to equip a land vehicle and comprising first and second electric drive machines suitable for delivering first and second motor torques respectively to drive in rotation drive wheels belonging respectively to first and second trains.

[0020] This monitoring device is characterized by the fact that it includes at least one processor and at least one memory arranged to perform the operations of determining a difference between a sum of first and second torques at the wheels, determined respectively as a function of the first and second motor torques delivered, and a setpoint of total torque to be supplied to the drive wheels, then, when a value as a function of this determined difference does not satisfy a chosen forward jump criterion, to trigger a prohibition of operation of one of the first and second electric drive machines and an imposition of operation in a degraded mode of the other of these first and second electric drive machines.

[0021] The invention also proposes a land vehicle, possibly of the automobile type, comprising, on the one hand, first and second electric drive machines capable of delivering respectively first and second motor torques to drive in rotation drive wheels belonging respectively to first and second trains, and, on the other hand, a monitoring device of the type of that presented above. Brief description of the figures

[0022] Other features and advantages of the invention will become apparent from an examination of the detailed description below, and the accompanying drawings, in which:

[0023] [Fig. 1] schematically and functionally illustrates an example of an embodiment of a land vehicle comprising a monitoring device according to the invention and a powertrain associated with a supervisory computer and comprising first and second electric drive machines and associated respectively with first and second speed sensors,

[0024] [Fig.2] schematically and functionally illustrates an example of an embodiment of a supervisory computer comprising an example of an embodiment of a monitoring device according to the invention, and

[0025] [Fig.3] schematically illustrates an example of an algorithm implementing a monitoring method according to the invention. Detailed description of the invention

[0026] The invention aims in particular to propose a monitoring method, and an associated DS monitoring device, intended to enable monitoring of the forward leaps of a land vehicle V and a powertrain (or GMP) comprising first MM1 and second MM2 electric driving machines associated with two independent drive trains T1 and T2.

[0027] In what follows, the land vehicle V is considered, by way of non-limiting example, to be of the automobile type. This is, for example, a car, as illustrated in [Fig. 1]. However, the invention is not limited to this type of land vehicle. It relates in fact to any type of land vehicle comprising a powertrain (or PWM) including at least first and second electric drive machines associated respectively with independent first and second drive trains.

[0028] Furthermore, in the following, by way of non-limiting example, it is assumed that the first MM1 and second MM2 electric drive machines are supplied with electrical energy by a low-pressure (LP) power source constituting a rechargeable (at least during charging phases) power (or "main" or "traction" battery). However, the first MM1 and second MM2 electric drive machines could also be supplied with electrical energy by a fuel cell.

[0029] Figure 1 schematically represents a (land) vehicle V comprising a purely electric powertrain (and therefore including first MM1 and second MM2 electric drive units), an on-board network RB, a service battery BS, an electrical power supply (here a power (or main or traction) battery) BP, a converter CV, a CS supervisory computer, first CM1 and second CM2 machine computers, a DS monitoring device according to the invention, and an SP1 and SP2 power electrical network.

[0030] The CV converter is of the DC / DC type (“Direct Current / Direct Current”). It is therefore responsible for converting a direct current from a first voltage to a second voltage.

[0031] The RB on-board network is an electrical power supply network to which electrical (or electronic) equipment (or components) that consume electrical energy are coupled.

[0032] The service battery BS is responsible for supplying electrical power to the vehicle's electrical system RB, supplementing, in this case, that supplied by the converter CV, which is powered by the electrical supply BP via the power supply network SP1 and SP2, and sometimes replacing, in this case, the converter CV. For example, this service battery BS can be configured as a very low voltage type battery (typically 12 V, 24 V, or 48 V). It is rechargeable at least by the (current) converter CV. In the following, by way of non-limiting example, the service battery BS is considered to be a 12 V lithium-ion type.

[0033] The transmission chain has a powertrain which includes, in particular, first MM1 and second MM2 (electric) drive machines, first AMI and second AM2 drive shafts, and first ATI and second AT2 transmission shafts. Here, "electric drive machine" means an electric machine arranged to provide (or deliver) a motor torque cmj (j = 1 or 2), defined by a torque setpoint cgj, to move the vehicle V when it is supplied with electrical energy by the power supply BP (this is referred to as the supply of a positive output torque), and possibly to recover torque, for example during regenerative braking (this is referred to as the supply of a negative output torque).

[0034] The operation of the powertrain is supervised by a supervisory computer CS. The control of the first power unit MM1 is ensured by an associated first machine computer CM1, notably based on a first setpoint cgi (j = 1) provided by the supervisory computer CS and defining the first motor torque cml (j = 1) that the latter (CS) wants the first power unit MM1 to supply (or deliver). The control of the second power unit MM2 is ensured by an associated second machine computer CM2, notably based on a second setpoint cg2 (j = 2) provided by the supervisory computer CS and defining the second motor torque cm2 (j = 2) that the latter (CS) wants the second power unit MM2 to supply (or deliver).

[0035] The first drive machine MM1 is coupled to the first drive shaft AMI to provide it with a first drive torque cml (defined by the first setpoint cgi) by rotational drive when it is supplied with electrical energy by the power supply BP via a first sub-section SP1 of the power electrical network. This first drive shaft AMI is coupled to a first gearbox RDI, which is also coupled to the first transmission shaft ATI, itself coupled to a first set of driving wheels Tl, preferably via a first differential DV.

[0036] Furthermore, the first driving machine MM1 is coupled to the first sub-part SP1 of the electrical power network and is subject at the level of its rotor to measurements of a first rml regime by a first regime sensor CRI.

[0037] It should be noted that the first train (motor) Tl is here located in the front part PVV of the vehicle V. But in a variant this first train Tl could be the second train (motor) T2 which is located in the rear part PRV of the vehicle V.

[0038] The second drive machine MM2 is coupled to the second drive shaft AM2 to provide it with a second drive torque cm2 (defined by the second setpoint cg2) by rotational drive when it is supplied with electrical energy by the power supply BP via a second sub-section SP2 of the power electrical network. This second drive shaft AM2 is coupled to a second gearbox RD2, which is also coupled, via a DC coupling device, to the second transmission shaft AT2, itself coupled to the second drive wheel assembly T2, preferably via a second differential DR.

[0039] Furthermore, the second drive machine MM2 is coupled to the second sub-part SP2 of the electrical power network and is subject at the level of its rotor to measurements of a second regime rm2 by a second regime sensor CR2.

[0040] It will be noted that when the first train (engine) T1 is located in the rear part PRV of the vehicle V, the second train (engine) T2 is located in the front part PVV of the vehicle V.

[0041] The DC coupling device is arranged to couple or decouple the second drive machine MM2 from the second transmission shaft AT2, according to the requirements defined by the supervisory computer CS. For example, this DC coupling device could be a clutch (possibly hydraulic). But it could also be a dog clutch, for example.

[0042] As those skilled in the art know, the determination of the motor torque cmj supplied at its output by an electric motor MMj (j = 1 or 2) can be done using the equation cmj = (mtj * ismj * pj) / rmj. pj is an efficiency coefficient of the electric motor MMj which is determined from the speed rmj of the rotor of the electric motor MMj (determined by the speed sensor CRj), from the measurement of the voltage mtj at the input terminals of the electric motor MMj, and the current ismj measured at the output of the electric motor machine MMj (as well as possibly the internal temperature of the stator of the electric motor machine MMj).

[0043] The preceding equation follows from the fact that the electrical power pelecj received by the electric motor MMj at its input terminals is equal to the product (mtj * ismj), and that the electric motor MMj provides at output a mechanical power pmecaj which is equal to the product (cmj * rmj) but also to the product (pelecj * pj), and that consequently we have the equation (cmj * rmj) = (mtj * ismj * pj).

[0044] For example, the determination of the motor torque cmj supplied on the output of an electric drive machine MMj can be carried out periodically by the machine computer CMj which controls this electric drive machine MMj.

[0045] The BP power supply is connected to the power grid via an interface device DI. This interface (or isolation) device DI is arranged to isolate, when necessary, the BP power supply (here) from at least the first MM1 or second MM2 motor and, more generally, from each sub-section SP1, SP2 of the power grid. It includes, for example, contactors (or switches), possibly based on MOSFET(s), which can each be placed in an open (or non-conducting) state or a closed (or conducting) state.

[0046] As illustrated, but not limited to, in [Fig. 1], the DI interface device can be part of a BB source housing associated with the BP power supply and which also includes voltage / current measurement means (not shown) and a CB source calculator. The BP power supply and the BB source housing can constitute a source assembly (or "pack").

[0047] The power supply BP is here a power (or main or traction) battery which may, for example, include electrical energy storage cells, possibly electrochemical (for example, lithium-ion (or Li-ion) or Ni-MH or Ni-Cd type). Also, for example, the power supply BP may be of the low-voltage type (typically 450 V by way of illustration). But it could also be of the medium-voltage or high-voltage type.

[0048] The CV converter is also responsible, here, during the driving phases of the vehicle V, for converting part of the electrical current stored in the electrical power source BP to supply converted electrical current to the on-board network RB and the auxiliary battery BS (to recharge it).

[0049] It will be noted, as illustrated non-limitingly in [Fig.1], that the CV converter can be part of a CH charger also comprising a CR' charging computer responsible, at least, for controlling the charging of the BP power supply source.

[0050] It should also be noted that in the example illustrated, but not limited to, in [Fig. 1], the vehicle V also includes a distribution box BD to which the auxiliary battery BS, the converter CV, and the on-board network RB are coupled. This distribution box BD is responsible for distributing the electrical energy stored in the auxiliary battery BS or produced by the converter CV into the on-board network RB to power the electrical components (or equipment) connected to the on-board network RB, according to power demands received (in particular from the powertrain control unit CS).

[0051] As mentioned above, the invention proposes in particular a monitoring method intended to allow monitoring of the forward leaps of vehicle V.

[0052] This (monitoring) method can be implemented at least partially by the DS monitoring device (illustrated at least partially in Figures 1 and 2), which for this purpose comprises at least one PR1 processor, for example a digital signal processor (or DSP), and at least one MD memory. This DS monitoring device can therefore be implemented as a combination of electrical or electronic circuits or components (or "hardware") and software modules (or "software"). For example, it could be a microcontroller.

[0053] The MD memory is random access memory (RAM) to store instructions for the implementation by the PR1 processor of at least part of the monitoring process. The PR1 processor may comprise integrated (or printed) circuits, or several integrated (or printed) circuits connected by wired or wireless connections. An integrated (or printed) circuit is defined as any type of device capable of performing at least one electrical or electronic operation.

[0054] In the example illustrated, but not limited to, Figures 1 and 2, the DS monitoring device is part of the CS supervisory control unit. However, this is not mandatory. Indeed, the DS monitoring device could comprise its own dedicated control unit, or it could be part of another control unit embedded in the vehicle V and performing at least one other function.

[0055] As illustrated non-limitingly in [Fig.3], the (monitoring) method according to the invention includes a step 10-50 which is implemented each time the first MM1 and second MM2 drive machines operate simultaneously to provide a total motor torque cmt equal to the sum of the first cml and second cm2 motor torques (i.e. cmt = cml + cm2).

[0056] These first cml and second cm2 motor torques are defined respectively by the first cgi and second cg2 setpoints, the sum of which is equal to a total torque setpoint cgt (i.e., cgt = cgi + cg2), for example determined by the CS supervisory computer. This total torque setpoint cgt represents the intended of the driver of vehicle V in terms of engine torque, which is, for example, defined by the percentage of depressment of the accelerator pedal PA.

[0057] Step 10-50 of the process includes a substep 20 in which the difference df between the sum sc of the first cri and second cr2 torques at the wheels, determined respectively as a function of the first cml and second cm2 motor torques delivered, and the setpoint of total torque cgt to be supplied to the driving wheels of the first Tl and second T2 trains is determined, i.e. df = sc - cgt = (cri + cr2) - (cgi + cg2).

[0058] For example, each wheel torque crj can be determined by multiplying the determined motor torque cmj by the reduction ratio fdj of the relevant gearbox RDj, i.e., crj = cmj*fdj. Also, for example, the determination of each wheel torque crj can be carried out periodically by the DS monitoring device in a substep 10 of step 10-50 (see [Fig. 3]). But it could also be carried out by the CS supervisory computer, for example.

[0059] Step 10-50 of the process also includes a substep 50 in which, when a value vl as a function of the determined difference df does not satisfy a chosen forward leap criterion, the operation of one of the first MM1 and second MM2 electric drive machines is prohibited (for example, the DS monitoring device triggers a prohibition of) and a degraded mode of operation is imposed on the other of these first MM1 and second MM2 electric drive machines.

[0060] For example, it is possible to prohibit the operation of the second electric drive machine MM2 and to impose the operation of the first electric drive machine MM1 in degraded mode.

[0061] Thanks to this detection of the non-satisfaction of the forward leap criterion (representative of a possible occurrence of a forward leap), the occurrence of this forward leap can be avoided without the need to use more precise CRI and CR2 speed sensors and / or first MM1 and second MM2 electric drive machines with more precise operation. This not only prevents vehicle V from colliding with an obstacle (object or living being), but also significantly increases the cost of vehicle V.

[0062] For example, in substep 50 of step 10-50, the degraded mode may consist of delivering a motor torque cmj (here cml) which is such as to cause the vehicle V to move at a speed below a chosen (second) threshold s2. Such a degraded mode is sometimes called in English "limp home".

[0063] Also, for example, the second threshold s2 chosen can be between 10 km / h and 20 km / h. As an illustrative example, this second threshold s2 can be equal to 17 km / h. But other values ​​for the second threshold s2 can be used. For example, this second threshold s2 can be selected during the development or testing phase of a vehicle similar to vehicle V.

[0064] Also, for example, in substep 50 of step 10-50, the operation of the first MM1 or second MM2 electric drive machine can be prohibited (for example, the DS monitoring device can trigger the prohibition of) by ceasing to transmit the first torque setpoint cgi for the first electric drive machine MM1 or the second torque setpoint cg2 for the second electric drive machine MM2. This cessation of transmission of the first cgi or second cg2 torque setpoint can be carried out by the CS supervisory computer, and it is immediately interpreted by the first CM1 or second CM2 machine computer as a prohibition of first or second current consumption from the BP power supply by the first MM1 or second MM2 electric drive machine.

[0065] But in an alternative embodiment the prohibition of operation of the first MM1 or second MM2 electric motive machine can result from the decoupling of the power supply source BP of the first SP1 or second SP2 sub-part of the power electrical network at the interface (or isolation) device DI, for example by action on at least some of its contactors (or switches), under the control of the source computer CB.

[0066] Also, for example, in step 10-50 the forward jump criterion can be chosen based on the duration dds during which the determined difference df exceeded a first threshold if chosen.

[0067] In this case, in step 10-50, the forward leap criterion can be a point p(df, dds), defined by the determined difference df and the duration dds during which this determined difference df exceeded the first threshold, located below a curve showing the evolution of a torque difference as a function of the duration of the threshold exceedance. It will be understood that the forward leap criterion is not satisfied (and therefore there is a risk of a forward leap) when the point p(df, dds) is located above the aforementioned evolution curve. Conversely, the forward leap criterion is satisfied (and therefore there is no risk of a forward leap) when the point p(df, dds) is located below (or on) the aforementioned evolution curve.

[0068] The definition of this evolution curve can, for example, be stored in a memory of the DS monitoring device. Furthermore, this evolution curve can, for example, be determined during the development or testing phase of a vehicle similar to vehicle V.

[0069] It should be noted that the evolution curve can result from the following reasoning, based on the fact that we do not want the vehicle V to suddenly move forward or backward by more than a predefined distance dpi (typically 50 cm) in less than a predefined duration dp2 (typically 1.4 seconds) due to a total torque at its drive wheels not desired by the driver and therefore not proportional to the depressment of the accelerator pedal PA.

[0070] We can therefore determine, for a given inertia iv of the vehicle V, a curve of evolution of the total torque at the drive wheels crt as a function of the time of over-torque at the drive wheels to avoid a displacement greater than the predefined distance dpi.

[0071] To do this, we begin by determining the vehicle displacement force V fdv, which is equal to the vehicle's inertia V iv multiplied by the vehicle's acceleration V av, i.e., fdv = iv*av. This vehicle displacement force V fdv being also equal to the total wheel torque crt multiplied by the wheel rotation speed rrr (i.e., fdv = crt*rrr), we therefore have the relation iv*av = crt*rrr, from which we deduce that the total wheel torque crt is equal to (iv*av) / rrr.

[0072] Also, for example, the first threshold chosen can be between 0 Nm and 5 Nm. As an illustrative example, this first threshold can be equal to 0 Nm. But other values ​​for the first threshold can be used. For example, this first threshold can be chosen during the development or testing phase of a vehicle similar to vehicle V.

[0073] Also, for example, and as illustrated non-limitingly in [Fig. 3], step 10-50 of the process may also include a substep 30 in which the value vl is determined as a function of the determined difference df. For this purpose, one (for example, the DS monitoring device) may, for example, use first cpl and second cp2 counters.

[0074] The first counter cpl is a counter for the sum of over-torques (or determined positive differences df). The second counter cp2 is a counter for the duration of the determined positive difference df. They are, for example, initialized to zero (0) when the driver switches on the ignition of vehicle V, and they are incremented after each determination of the difference df, for example in the following way.

[0075] If the newly determined difference df is greater than the first threshold (for example, equal to 0 Nm), and if the current value of the second counter cp2 is less than the predefined duration dp2 (for example, equal to 1.4 seconds), the new value of the first counter cpl becomes equal to the sum of its previous current value and this newly determined difference df, and the new value of the second counter cp2 becomes equal to the sum of its previous current value and the refresh period dds (for example, equal to 100 milliseconds). In other words, if df > 0 and cp2(t) < 1.4 s, then cpl(t+l) = cpl(t) + df = vl and cp2(t+l) = cp2(t) + 100 ms.

[0076] Once this update of the first cpl and second cp2 counters has been carried out, as illustrated non-limitingly in [Fig. 3], step 10-50 of the process may include a substep 40 in which one (for example the DS monitoring device) can determine whether the new value of the first cpl counter, which is equal to the vl value, is located below the evolution curve shown above.

[0077] If the answer is no, this means that the forward jump criterion is not met, and therefore there is a potential forward jump problem. Consequently, substep 50 is performed (for example, by the DS monitoring device).

[0078] Conversely, if the answer is yes, this means that the forward jump criterion is met, and therefore there is no forward jump problem. Consequently, substep 10 is performed again (for example, by the DS monitoring device) with refreshed values.

[0079] It should be noted that when df < 0, then cpl(t+l) = 0 and cp2(t+l) = 0 (resetting to zero (0) the first cpl and second cp2 counters). Similarly, when cp2(t) > 1.4 s, then cpl(t+l) = 0 and cp2(t+l) = 0 (resetting to zero (0) the first cpl and second cp2 counters).

[0080] Also, for example, in substep 50 of step 10-50, one can also perform (for example, the DS monitoring device can also trigger the execution) in vehicle V at least one action which is chosen from:

[0081] - an alert to the driver of vehicle V by means of a warning light on the latter (V) and / or a text message and / or an audio message indicating a need for vehicle V to be checked at an after-sales service center, and

[0082] - a recording of at least one fault code representative of a bonding problem ahead of vehicle V.

[0083] For example, in the event of a driver alert, the warning light may be part of the instrument panel or displayed on a vehicle display screen (e.g., the central instrument cluster installed on or in the instrument panel). It may be a warning light specifically for the forward lurch problem or a general service warning light (not specifically designed for this purpose).

[0084] Also, for example, in the event of an alert from the driver, the text alert message can be displayed on at least one EA screen of the vehicle V (for example, the dashboard or the central instrument cluster) or on the screen of a driver's smart phone (or "smartphone").

[0085] Also, for example, in the event of an alert from the driver, the audible (or audio) alert message can be broadcast by at least one speaker of the vehicle V or the aforementioned smartphone.

[0086] It should be noted that the storage of each fault code can, for example, be done in a (possibly read-only) memory of the DS monitoring device or the CS supervisory control unit. This allows the after-sales service that will service vehicle V to be notified that a forward leap problem has been detected, and thus facilitates the search for the origin of this problem by the after-sales service.

[0087] It should also be noted that when vehicle V is restarted after the operation of the first MM1 or second MM2 electric drive unit has been prohibited and the operation of the second MM2 or first MM1 electric drive unit has been imposed in degraded mode, the "normal" (unrestricted) operation of the first MM1 and second MM2 electric drive units can again be authorized (for example, by the DS monitoring device) if the vl value again meets the forward leap criterion. Conversely, if the vl value still does not meet the forward leap criterion, the operation of the first MM1 or second MM2 electric drive unit and the operation of the second MM2 or first MM1 electric drive unit in degraded mode remain in effect.

[0088] It should also be noted, as illustrated but not limited to [Fig. 2], that the CS supervisory computer (or the DS monitoring device computer) may also include a mass memory MME, in particular for storing the total torque setpoint cgt and the first and second wheel torques or the first and second engine torques cm1 and cm2, as well as any intermediate data involved in all its calculations and processing. Furthermore, this CS supervisory computer (or the DS monitoring device computer) may also include an input interface IE for receiving at least the total torque setpoint cgt and the first and second wheel torques or the first and second engine torques cm1 and cm2, possibly after having been shaped and / or demodulated and / or amplified, in a manner known per se, by means of a PR2 digital signal processor.Furthermore, this CS supervisory computer (or the DS monitoring device computer) may also include an IS output interface, in particular to deliver each message requiring a ban on the operation of the first MM1 or second MM2 electric motor, each message imposing operation in degraded mode of the second MM2 or first MM1 electric motor, and each possible message triggering an alert or storing a fault code.

[0089] It should also be noted that the invention also proposes a computer program product (or computer program) comprising a set of instructions which, when executed by processing means of the type of electronic circuits (or hardware), such as for example the PR1 processor, is suitable for implementing the monitoring process described above to monitor the forward leaps of the vehicle V.

Claims

Demands

1. A monitoring method for a land vehicle (V) comprising first (MM1) and second (MM2) electric drive machines adapted to deliver first and second motor torques respectively to rotate drive wheels belonging respectively to first (T1) and second (T2) trains, characterized in that it comprises a step (10-50) in which a difference is determined between a sum of first and second torques at the wheels, determined respectively as a function of said first and second motor torques delivered, and a setpoint for the total torque to be supplied to said drive wheels, and then, when a value based on said determined difference does not satisfy a chosen forward leap criterion,The operation of one of the aforementioned first (MM1) and second (MM2) electric drive machines is prohibited, and operation in a degraded mode is imposed on the other of the aforementioned first (MM1) and second (MM2) electric drive machines.

2. Method according to claim 1, characterized in that in said step (10-50) said forward leap criterion is chosen as a function of a duration during which said determined difference has exceeded a first chosen threshold.

3. Method according to claim 2, characterized in that in said step (10-50) said forward leap criterion is a point, defined by said determined difference and said time during which this determined difference exceeded said first threshold, located below a curve of evolution of a torque difference as a function of a threshold exceedance time.

4. A method according to claim 2 or 3, characterized in that in said step (10-50) said first threshold selected is between 0 Nm and 5 Nm

5. A method according to any one of claims 1 to 4, characterized in that in said step (10-50) said degraded mode consists of delivering a motor torque suitable for causing a movement of said vehicle (V) at a speed below a second chosen threshold.

6. Method according to claim 5, characterized in that in said step (10-50) said second threshold chosen is between 10 km / h and 20 km / h.

7. A method according to any one of claims 1 to 6, characterized in that in said step (10-50) at least one action selected from an alert to a driver of said vehicle (V) by means of a warning light of said vehicle (V) and / or a text message and / or an audible message indicating a need for verification of said vehicle (V), and a recording of at least one fault code representative of a forward leap problem of said vehicle (V).

8. Product computer program comprising an instruction set which, when executed by processing means, is suitable for implementing the monitoring method according to any one of claims 1 to 7, in a land vehicle (V) and comprising first (MM1) and second (MM2) electric drive machines suitable for delivering first and second motor torques respectively to drive drive wheels belonging respectively to first (T1) and second (T2) trains, for monitoring forward leaps of said vehicle (V).

9. A monitoring device (MD) for a land vehicle (V) comprising first (MM1) and second (MM2) electric drive machines adapted to deliver first and second motor torques respectively to rotate drive wheels belonging respectively to first (T1) and second (T2) trains, characterized in that it comprises at least one processor (PR1) and at least one memory (MD) arranged to perform the operations of determining a difference between a sum of first and second torques at the wheels, determined respectively as a function of said first and second motor torques delivered, and a setpoint for the total torque to be supplied to said drive wheels, and then, when a value based on said determined difference does not satisfy a chosen forward leap criterion,to trigger a shutdown of one of the said first (MM1) and second (MM2) electric drive machines and a requirement to operate in a degraded mode of the other of the said first (MM1) and second (MM2) electric drive machines.

10. A land vehicle (V) comprising first (MM1) and second (MM2) electric drive machines capable of delivering first and second motor torques respectively to drive in rotation drive wheels belonging respectively to first (T1) and second (T2) driving wheel assemblies, characterized in that it further comprises a monitoring device (DS) according to claim 9.

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