CONTROL OF DISCONNECTING A WHEEL INDIRECTLY COUPLED TO A DIFFERENTIAL COUPLED TO AN ELECTRIC DRIVE MACHINE OF A LAND VEHICLE

Abstract

A control method is implemented in a land vehicle comprising a first half-train equipped with a first wheel, a second half-train equipped with a second wheel and a coupling device that can be placed in connected and disconnected states, and an electric drive unit coupled to a differential that can be placed in locked and unlocked states and coupled to the half-trains. This method includes a step (10-60) in which, upon receiving a request to disconnect the second wheel, it is determined whether the differential is in the unlocked state, and if so, the disconnection is authorized; if not, the differential is ordered to be placed in the unlocked state, and then it is determined again whether the differential is indeed in the unlocked state. Figure 3

Description

Title of the invention: CONTROL OF THE DISCONNECTION OF A WHEEL INDIRECTLY COUPLED TO A DIFFERENTIAL COUPLED TO AN ELECTRIC DRIVE MACHINE OF A LAND VEHICLE Technical field of the invention

[0001] The invention relates to land vehicles comprising an electric drive unit coupled to two wheel sets via a differential, and more specifically to the control, within such vehicles, of the disconnection of a wheel from its wheel set. Prior art

[0002] Certain land vehicles, possibly of the motor vehicle type, include a transmission chain comprising, for example in a rear part, a first half-train equipped with a first wheel, a second half-train equipped with a second wheel and a coupling device, and an electric drive machine coupled to a differential that can be placed in locked and unlocked states and coupled to the first and second half-trains.

[0003] Herein, "electric drive machine" means an electric machine arranged at least so as to provide motor torque to the first and second half-trains, to which it is coupled via the associated differential, to move its vehicle when it is supplied with electrical energy.

[0004] In the aforementioned vehicles, the coupling device can be selectively placed either in a connected state in which the second wheel is connected (or coupled) to the second half-train (and therefore driven simultaneously with the latter), or in a disconnected state in which the second wheel is disconnected (or decoupled) from the second half-train (and therefore cannot be driven simultaneously with the latter). This advantageously allows the electric drive unit to be decoupled from the first and second half-trains.

[0005] When the coupling device is selectively placed in its connected state and the differential is selectively placed in an unlocked state, this allows for different rotational speeds of the first and second wheels, which is useful when cornering. Conversely, when the coupling device is selectively placed in its connected state and the differential is selectively placed in a locked state, this imposes identical rotational speeds of the first and second wheels.

[0006] In the presence of such an arrangement, when the electric drive machine is decoupled from the first and second half-trains while the differential is in its state If the differential is locked, the torque and speed of the electric drive unit are entirely directed to the first wheel, which is the only one connected to its first half-axle. Therefore, the vehicle risks spinning out, which can be dangerous for the safety of the vehicle and its passengers, as well as for the safety of objects and people in the vehicle's vicinity. Consequently, before disconnecting (or decoupling) the electric drive unit from the first and second half-axles (by decoupling the second wheel from its second half-axle), it is essential that the differential be in its unlocked state.

[0007] Currently, the vehicle driver must place the differential in its unlocked state (first action) before ordering the coupling device to be placed in its disconnected state (second action).This requires not only that the driver understands the reason for these actions, but also that they consistently remember to perform them. However, even when the driver performs these actions in the correct order and the differential warning light indicates that it is in its unlocked state, the information provided by the light is not guaranteed to be accurate because the information indicating the differential's state is not 100% reliable. It is possible that the light may indicate an unlocked state when, in reality, the differential is locked or in an uncertain state.

[0008] The invention therefore aims in particular to improve the situation by automating the control of the disconnection of the second wheel from its second half-train. Presentation of the invention

[0009] In particular, it proposes for this purpose a control method intended to be implemented in a land vehicle comprising:

[0010] - a first half-train equipped with a first wheel,

[0011] - a second half-train equipped with a second wheel and a coupling device which can be placed in connected and disconnected states in which the second wheel is respectively connected and disconnected, and

[0012] - an electric drive machine coupled to a differential that can be placed in blocked and unblocked states coupled to the first and second half-trains.

[0013] This control method is characterized by the fact that it includes a step in which, in the presence of a request to disconnect the second wheel, it is determined whether the differential is in the unblocked state, and if so, the disconnection is authorized, while if not, a placement of the differential in the unblocked state is ordered, and then it is determined again whether the differential is actually in the unblocked state.

[0014] Thanks to the invention, it is now certain that when the coupling device is allowed to be placed in its disconnected state, the differential is indeed in its unblocked state, which ensures that the torque and speed of the driving machine will not be entirely directed to the first wheel of the first half-train.

[0015] The control method according to the invention may include other features which may be taken separately or in combination, and in particular:

[0016] - in its step, it can be ordered that the electric drive machine supply a engine torque varying according to a predefined variation law in order to determine if the first and second wheels have identical behaviors, then in the negative we can consider that the differential is in the unlocked state, while in the affirmative we can order a placement of the differential in the unlocked state then we can determine again if the differential is indeed in the unlocked state;

[0017] - in the presence of the first option, in its stage, when the first and second wheels have identical behavior, we can determine if the vehicle moves substantially in a straight line, and if so (straight line) we can consider that the differential is in an uncertain state, while if not (turning) we can consider that the differential is in a locked state;

[0018] - in the presence of the last sub-option, in its step, it is possible to determine if a the steering wheel of the vehicle has an angle of rotation during operation greater than a chosen threshold, and in the affirmative we can consider that the vehicle is in a turn and therefore that the differential is in the locked state, while in the negative we consider that the vehicle is moving substantially in a straight line and therefore that the differential is in the uncertain state;

[0019] - alternatively, and still in the presence of the last sub-option, in its step, we can determine if a current geographical position of the vehicle corresponds to the presence of the latter on a section of traffic lane that is substantially straight, and if so, the differential can be considered to be in an uncertain state, while if not, the differential can be considered to be in a locked state;

[0020] - also in the presence of the first option, in its step, the law of variation predefined may consist of a monotonic increase followed by a monotonic decrease down to a zero value;

[0021] - in its step, before determining whether the differential is in the unblocked state, one can start by determining if the differential is in the blocked state, and if not, we can determine if the differential is in the unblocked state, while if so, we can order a placement of the differential in the unblocked state and then we can determine if the differential is actually in the unblocked state.

[0022] The invention also proposes a computer program product comprising a set of instructions which, when executed by processing means, is specific to to implement a control method of the type presented above, in a land vehicle comprising a first half-train equipped with a first wheel, a second half-train equipped with a second wheel and a coupling device that can be placed in connected and disconnected states in which the second wheel is respectively connected and disconnected, and an electric drive machine coupled to a differential that can be placed in locked and unlocked states and coupled to the first and second half-trains, to control the disconnection of the second wheel.

[0023] The invention also proposes a control device for equipping a land vehicle comprising:

[0024] - a first half-train equipped with a first wheel,

[0025] - a second half-train equipped with a second wheel and a coupling device which can be placed in connected and disconnected states in which the second wheel is respectively connected and disconnected, and

[0026] - an electric drive machine coupled to a differential that can be placed in blocked and unblocked states coupled to the first and second half-trains.

[0027] This control device is characterized by the fact that it comprises at least one processor and at least one memory arranged to perform the operations consisting, in the presence of a request to disconnect the second wheel, of determining whether the differential is in the unblocked state, and if so, authorizing the disconnection, or if not, ordering a placement of the differential in the unblocked state and then determining again whether the differential is actually in the unblocked state.

[0028] The invention also proposes a land vehicle, possibly of the automobile type, comprising, on the one hand, a first half-train equipped with a first wheel, a second half-train equipped with a second wheel and a coupling device that can be placed in connected and disconnected states in which the second wheel is respectively connected and disconnected, and an electric drive machine coupled to a differential that can be placed in locked and unlocked states and coupled to the first and second half-trains, and, on the other hand, a control device of the type of that presented above. Brief description of the figures

[0029] Other features and advantages of the invention will become apparent from an examination of the detailed description below, and the accompanying drawings, in which:

[0030] [Fig-1] schematically and functionally illustrates an example of the realization of a land vehicle comprising a transmission chain including in particular a control device according to the invention and an electric drive machine controlled by a machine computer and coupled to a differential, itself coupled to wheel assemblies, one of which includes a coupling device,

[0031] [Fig.2] schematically and functionally illustrates an example of an embodiment of a machine computer comprising an example of an embodiment of a control device according to the invention, and

[0032] [Fig.3] schematically illustrates an example of an algorithm implementing a control method according to the invention. Detailed description of the invention

[0033] The invention aims in particular to provide a control method, and an associated DC4 control device, intended to allow control of the disconnection, by action on a (first) coupling device DC1, of a (second) wheel RR2 of a (second) half-train DT2 coupled, like a (first) half-train DTI (to which a (first) wheel RR1 is connected), to a differential DR which is also coupled to a (first) electric driving machine MM1 of a land vehicle V.

[0034] 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 transmission chain including a differential coupled to a wheel assembly, equipped with a coupling device, and to an electric drive unit. Thus, it relates to commercial vehicles, motorhomes, minibuses, coaches, trucks, road maintenance vehicles, construction equipment, and agricultural machinery, for example.

[0035] Furthermore, in what follows, by way of non-limiting example, the land vehicle V is considered to comprise a hybrid (thermal and electric) powertrain. However, the powertrain could be of the all-electric type (and in this case, propulsion is provided exclusively by at least one electric motor (here MM1)).

[0036] A (land) vehicle V is schematically represented in [Fig.1] comprising a transmission chain including in particular a control device DC4 according to the invention, a service battery BS, a main battery BP, a converter CV, and a first electric drive machine MM1, controlled by a machine computer CM and coupled to a differential DR, itself coupled to first DTI and second DT2 half-wheel assemblies, one of which (here DT2) includes a first coupling device DC1 having disconnected and connected states.

[0037] It should be noted that in the example illustrated, but not limited to, in [Fig. 1], the transmission chain also includes a second thermal power unit MM2 and a possible third electric power unit MM3, and a supervisory computer CS. However, the powertrain (or PMU) of the transmission chain could include only the first electric power unit MM1, or the first MM1 and third MM3 electric drive machines, or the first electric drive machine MM1 and the second thermal drive machine MM2.

[0038] It is recalled that here the term "motive machine" means a machine arranged at least in such a way as to provide motor torque to move the vehicle V when it is supplied with motive power.

[0039] The operation of the transmission chain (and therefore of the GMP) is supervised by a CS supervision computer.

[0040] The auxiliary battery BS is responsible for supplying electrical power to the vehicle's electrical system V, supplementing that supplied by the CV converter, which is powered by the main battery BP via a main electrical circuit, and sometimes replacing this CV converter. For example, this auxiliary battery BS may be configured as a very low voltage type battery (typically 12 V, 24 V, or 48 V). It is rechargeable, at least by the CV converter. In the following, for the sake of non-limiting example, the auxiliary battery BS is considered to be a 12 V lithium-ion type.

[0041] The on-board network is an electrical power supply network to which electrical (or electronic) equipment (or components) that consume electrical energy are coupled.

[0042] The main electrical circuit (or "high voltage" or "power" circuit) is connected, on the one hand, to the main battery BP via an interface device, and, on the other hand, to electronic equipment, such as the CV converter and the first MM1 and third MM3 (electric) drive machines. It also allows the main battery BP to be recharged by an external power source temporarily connected to a vehicle charging connector V.

[0043] The first electric drive machine MM1 (here an electric motor) is coupled to the main battery BP via the main electrical circuit, in order to be supplied with electrical energy, and also possibly to supply this main battery BP with electrical energy during a regenerative braking phase.

[0044] Furthermore, this first electric traction machine MM1 is coupled to the differential DR via a first drive shaft ATI. This differential DR is coupled to a first wheel assembly T1 subdivided into a first half-assembly DTI equipped with a first wheel RR1 and a second half-assembly DT2 equipped with a second wheel RR2 and the first coupling device DC1. In addition, the differential DR can be selectively placed in an unlocked state, allowing different rotational speeds of the first RR1 and second RR2 wheels, or in a locked state, imposing identical rotational speeds of the first RR1 and second RR2 wheels.

[0045] The first coupling device DC1 can be selectively placed in a connected state in which the second wheel RR2 is connected (or coupled) to the second half- train DT2 can be driven by the differential DR, or in a disconnected state in which the second wheel RR2 is disconnected (or decoupled) from this second half-train DT2.

[0046] For example, the first coupling device DC1 can be a dog clutch device. But this is not mandatory.

[0047] The first train Tl is here located in the rear part PRV of the vehicle V. But in a variant this first train Tl could be the one which is here referenced T2 and which is located in the front part PVV of the vehicle V.

[0048] The operation of the first electric drive machine MM1 (and preferably of the first coupling device DC1) is controlled by a machine computer CM, and supervised by the supervisory computer CS.

[0049] It should be noted that in the example illustrated, but not limited to, in [Fig. 1], the transmission chain also includes a first gearbox BV1 interposed between the output of the first electric drive machine MM1 and the first transmission shaft ATI. However, this is not mandatory.

[0050] The second drive machine MM2 is a thermal engine and, when fueled, produces engine torque and supplies it to a drive shaft AM which is connected to a second coupling device DC2. This latter device (DC2) is used to couple the second drive machine MM2 to a primary shaft AP of a second gearbox BV2 to supply it with the engine torque produced by the second drive machine MM2.

[0051] The output shaft of the second gearbox BV2 is coupled to a second transmission shaft AT2 which is itself coupled to the second wheel assembly T2, preferably via a differential DV.

[0052] For example, the second coupling device DC2 could be a hydraulic circuit clutch. But it could be of another type.

[0053] Also, for example, the second gearbox BV2 can be automated. Thus, it can, for example, be a dual-clutch (or DCT (“Dual Clutch Transmission”)) gearbox. But this is not mandatory.

[0054] It should be noted that in the example illustrated, but not limited to, in [Fig. 1], the crankshaft of the second drive unit MM2 is also coupled to a belt, which is itself coupled to a starter-alternator AD that is supplied with electrical energy by the auxiliary battery BS (and which can also recharge the latter (BS)). Thus, the starter-alternator AD can supply torque to the belt, which can then supply this torque to the crankshaft.

[0055] The third drive machine MM3 is electric and charged, when supplied with electrical energy by the main battery BP, with producing a motor torque.

[0056] Furthermore, this third drive machine MM3 is, in this instance, designed to be coupled, downstream of the second coupling device DC2, by a third coupling device DC3, to the second gearbox BV2 to supply it with the engine torque it produces. However, in an unillustrated variant, the third drive machine MM3 could be directly inserted between the output of the second coupling device DC2 and the primary shaft AP.

[0057] The operation of the third electric drive machine MM3 is controlled by a machine computer (not shown), and supervised by the CS supervisory computer.

[0058] The third coupling device DC3 can be placed in coupled and decoupled states, depending on a state setpoint generated by the GMP CS supervisory computer.

[0059] Furthermore, this third coupling device DC3 can, for example, include a cascade of gears linking the third drive machine MM3 to the input of the second gearbox BV2 (downstream of the second coupling device DC2).

[0060] 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 main battery BP to supply converted electrical current to the on-board network and the auxiliary battery BS (to recharge it).

[0061] The main (or "traction" or "power") battery BP supplies, in particular, the first MM1 and third MM3 electric motors. It 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 main battery BP may be of the low-voltage type (typically 450 V, for illustrative purposes). But it could also be of the medium-voltage or high-voltage type.

[0062] As mentioned above, the invention proposes in particular a control method intended to allow the control of the disconnection of the second wheel RR2 of the land vehicle V. It should be noted that in the example illustrated non-limitingly on [Fig.1], this disconnection of the second wheel RR2 is intended to allow the movement of the vehicle V only by means of the motor torque supplied to its second axle T2 (here the front axle) and produced by the second driving machine MM2 and / or the third driving machine MM3.

[0063] This (control) method can be implemented at least partially by the DC4 control 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 DC4 control device can therefore be implemented in the form of a combination of circuits or electrical or electronic components (or "hardware") and software modules (or "software"). For example, this could be a microcontroller.

[0064] The MD memory is random access memory (RAM) to store instructions for the implementation by the PR1 processor of at least part of the control 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.

[0065] In the example illustrated, but not limited to, Figures 1 and 2, the DC4 control device is part of the CM machine computer. However, this is not mandatory. Indeed, the DC4 control device could comprise its own dedicated computer, which is then coupled to the CM machine computer, or it could be part of another computer in the vehicle V, such as the CS supervisory computer.

[0066] As illustrated non-limitingly in [Fig.3], the (control) method according to the invention includes a step 10-60 which is implemented each time the vehicle V has its GMP in operation and its first electric motive machine MM1 is coupled to the first train Tl (due to the placement of the first coupling device DC1 in its connected (or coupled) state).

[0067] Step 10-60 of the process includes a substep 40 in which, in the presence of a request to disconnect the second wheel RR2, one (for example the control device DC4) determines whether the differential DR is in its unblocked state.

[0068] It should be noted that the request to disconnect the second wheel RR2 can originate from the driver of the vehicle V or from a computer of the latter (V), such as for example the supervision computer CS.

[0069] If the differential DR is in its unblocked state (and therefore in the affirmative), step 10-60 of the process also includes a substep 50 in which the requested disconnection is authorized (for example, by the control device DC4). Conversely, if the differential DR is in its blocked state or in an uncertain state (and therefore in the negative), step 10-60 of the process also includes a substep 20 in which the differential DR is placed in its unblocked state (for example, by the control device DC4), and then at least substep 40 is performed again (for example, by the control device DC4) to determine once more whether the differential DR is indeed in its unblocked state.

[0070] Thus, it is automatically ensured that the differential DR is in its unlocked state before allowing the first coupling device DC1 to be placed in its disconnected state (and therefore the second wheel RR2 to be disconnected from its second half-train DT2), which guarantees that the torque and speed of the first machine The MM1 drive unit will not be entirely directed towards the first RR1 wheel of the first DTI half-train. This enhances the safety of the vehicle and its passengers, as well as the safety of objects and people in the vicinity of the vehicle.

[0071] In order to determine (or verify) whether the differential DR is in its unblocked state, one can, for example, proceed as described below (in a non-limiting manner).

[0072] For example, and as illustrated, but not limited to, in [Fig. 3], step 10-60 may include a substep 30 in which the first electric drive unit MM1 (for example, the DC4 control device) may be instructed to supply a motor torque that varies according to a predefined variation law in order to apply stress to the first train T1, and more specifically to its first RR1 and second RR2 wheels. It will be understood that this application is intended to determine whether the first RR1 and second RR2 wheels exhibit identical behavior. This latter determination is carried out in substep 40 of step 10-60.

[0073] It should be noted that the first RR1 and second RR2 wheels can be considered to have identical behavior if they have substantially identical rotational speeds or if they receive substantially the same motor torque. The rotational speed at a wheel RR1 or RR2 can, for example, be estimated by a sensor coupled to its wheel hub, which can constitute an angular encoder determining the number of teeth passing in front of it per second. The motor torque received at a first RR1 or second RR2 wheel can be estimated from measurements taken by at least one sensor coupled to that first RR1 or second RR2 wheel.

[0074] If the first RR1 and second RR2 wheels exhibit different behaviors (and are therefore negative in substep 40), the differential DR can be considered to be in its unlocked state (for example, by the DC4 control device). Indeed, as mentioned above, the first RR1 and second RR2 wheels can only exhibit different behaviors if the differential DR is in its unlocked state. In this situation, substep 50 is performed (for example, by the DC4 control device) to allow the requested disconnection.

[0075] Conversely, if the first RR1 and second RR2 wheels exhibit identical behavior (and therefore, if so, in substep 40), one (for example, the control device DC4) can command the differential DR to be placed in its unlocked state. Indeed, as indicated above, the first RR1 and second RR2 wheels can exhibit identical behavior whether the differential DR is in its locked state or whether the differential DR is in its unlocked state and the vehicle V is moving substantially in a straight line. In these situations, one (for example, the control device DC4) can perform substep 20 again. Then, one (for example, the control device DC4) can determine (or verify) again whether the differential DR is indeed in its unblocked state by performing substeps 30 and 40 again.

[0076] For example, and as illustrated, but not limited to, in [Fig. 3], step 10-60 may include a substep 60 in which, when the first RR1 and second RR2 wheels exhibit identical behavior, it is possible (for example, by the control device DC4) to determine whether the vehicle V is moving substantially in a straight line. This latter determination is intended to resolve any ambiguity regarding the actual state of the differential DR. Indeed, if the vehicle V is in a turn (and therefore in the negative direction (not in a straight line)), it is possible (for example, by the control device DC4) to consider that the differential DR is in a locked state, which requires that the first RR1 and second RR2 wheels exhibit identical behavior.On the other hand, if the vehicle V is moving substantially in a straight line (and therefore in the affirmative), we (for example the control device DC4) can consider that the differential DR is in an uncertain state, since the differential DR is assumed to be in its unlocked state which allows different behaviors of the first RR1 and second RR2 wheels even though these behaviors are identical.

[0077] It will be noted that when the differential DR is in an uncertain state, such as when the differential DR is in its blocked state, substep 20 is performed again (for example, by the control device DC4), and then whether the differential DR is actually in its unblocked state is determined (or verified) again by performing substeps 30 and 40 again (for example, by the control device DC4).

[0078] In order to determine whether the vehicle V moves substantially in a straight line, at least two methods can be used, as described below.

[0079] In a first manner, in substep 60 of step 10-60, when the first RR1 and second RR2 wheels exhibit identical behavior, it is possible (for example, the control device DC4) to determine whether the steering wheel of vehicle V has an angle of rotation arv that exceeds a chosen threshold si (characteristic of a turn). If so (arv > si and identical behavior), it can be considered (for example, the control device DC4) that vehicle V is turning and therefore that the differential DR is in its locked state. Conversely, if not (arv < si and identical behavior), it can be considered (for example, the control device DC4) that vehicle V is moving substantially in a straight line and therefore that the differential DR is in an uncertain state.

[0080] For example, the chosen threshold can be between 10° and 30°. As an illustrative example, the chosen threshold can be 20°. However, other values ​​for the chosen threshold can be used. For example, the value of the threshold can be chosen during the development (or testing) phase of vehicle V.

[0081] In a second way, in substep 60 of step 10-60, when the first RR1 and the second RR2 wheels have identical behavior; one (for example, the DC4 control device) can determine if the current geographical position of vehicle V corresponds to its presence on a section of road that is substantially straight. If so, the differential DR can be considered to be in an uncertain state, while if not, the differential DR can be considered to be in its locked state.

[0082] It should be noted that the current geographical position of vehicle V can, for example, be determined by a satellite guidance device (or GPS) present in vehicle V. It should also be noted that the characteristics of the section of road on which vehicle V is traveling can be determined in a map database present in vehicle V or accessible in a server with which a communication module present in vehicle V can communicate wirelessly.

[0083] Also, for example, in substep 30 of step 10-60 the predefined variation law may consist of a monotonic increase followed by a monotonic decrease to a zero value.

[0084] For example, the DC4 control device can generate a request requiring the first electric drive machine MM1 to provide a motor torque, defined by the predefined variation law, to the machine computer CM, and, upon receiving this request, the machine computer CM drives the first electric drive machine MM1 to provide this motor torque.

[0085] Preferably, the amplitude of the monotonic increase in engine torque is small so as not to significantly disrupt the operation of the transmission chain and to avoid excessive consumption of electrical energy stored in the main battery BP. For example, this amplitude of the monotonic increase may be between 3 Nm and 10 Nm. As an illustrative example, the amplitude of the monotonic increase may be equal to 5 Nm. However, other values ​​for the amplitude of the monotonic increase may be used. For example, the value of the amplitude of the monotonic increase may be chosen during the development (or testing) phase of the vehicle V.

[0086] Also, for example, and as illustrated non-limitingly in [Fig. 3], step 10-60 may include a substep 10 in which, before determining whether the differential DR is in its unblocked state, one (for example, the control device DC4) may first determine whether the differential DR is in its blocked state. This latter determination may be made using the machine computer CM, for example. If the negative result (unblocked state), one (for example, the control device DC4) performs substeps 30 and 40 to determine whether the differential DR is in its unblocked state, since the information just obtained from the computer of machine CM is not 100% reliable. On the other hand, in the affirmative (blocked state) we (for example the control device DC4) perform substep 20 to order a placement of the differential DR in its unblocked state, then we (for example the control device DC4) perform substeps 30 and 40 to determine (or verify) if the differential DR is indeed in its unblocked state.

[0087] It will also be noted, as illustrated non-limitingly in [Fig.2], that the machine computer CM (or the computer of the control device DC4) may also include a mass memory MEM, in particular to store the possible current angle of rotation of the steering wheel or the possible current geographical position of the vehicle V and the possible characteristics of the portion of traffic lane on which the vehicle V is traveling, as well as any intermediate data involved in all its calculations and processing.Furthermore, this machine computer CM (or the computer of the control device DC4) may also include an input interface IE for receiving at least the possible current steering wheel rotation angle or the possible current geographical position of the vehicle V and the possible characteristics of the portion of traffic lane on which the vehicle V is traveling, for use in calculations or processing, possibly after having shaped and / or demodulated and / or amplified them, in a manner known per se, by means of a digital signal processor PR2.Furthermore, this machine computer CM (or the control device computer DC4) can also include an IS output interface, notably to deliver a message authorizing the disconnection of the second wheel RR2, or a possible message (or command) to place the differential DR in its unblocked state, or even a possible message (or command) to supply by the first electric driving machine MM1 a motor torque varying according to the predefined variation law.

[0088] It will 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 control method described above to control the disconnection of the second wheel RR2 in the land vehicle V.

Claims

Demands

1. A control method for a land vehicle (V) comprising i) a first half-train (DTI) equipped with a first wheel (RR1), ii) a second half-train (DT2) equipped with a second wheel (RR2) and a coupling device (DC1) that can be placed in connected and disconnected states in which said second wheel (RR2) is respectively connected and disconnected, and iii) an electric drive machine (MM1) coupled to a differential (DR) that can be placed in locked and unlocked states and coupled to said first (DTI) and second (DT2) half-trains, characterized in that it comprises a step (10-60) in which, in the presence of a request to disconnect said second wheel (RR2), it is determined whether said differential (DR) is in said unlocked state, and if so, said disconnection is authorized.whereas, if negative, a placement of said differential (DR) is ordered in said unblocked state, and then it is determined again whether said differential (DR) is indeed in said unblocked state.

2. The method according to claim 1, characterized in that in said step (10-60) said electric motor machine (MM1) is ordered to provide a motor torque varying according to a predefined variation law in order to determine whether said first (RR1) and second (RR2) wheels have identical behaviors, then in the negative said differential (DR) is considered to be in said unblocked state, while in the affirmative said differential (DR) is ordered to be placed in said unblocked state and then it is determined again whether said differential (DR) is actually in said unblocked state.

3. Method according to claim 2, characterized in that in said step (10-60), when said first (RR1) and second (RR2) wheels have identical behaviors, it is determined whether said vehicle (V) is moving substantially in a straight line, and if so, said differential (DR) is considered to be in an uncertain state, while if not, said differential (DR) is considered to be in said blocked state.

4. The method according to claim 3, characterized in that in said step (10-60) it is determined whether a steering wheel of said vehicle (V) has an angle of rotation during operation greater than a chosen threshold, and if so, said vehicle (V) is considered to be in a turn and therefore said differential (DR) is in said locked state, while if not, considers that said vehicle (V) moves substantially in a straight line and therefore that said differential (DR) is in said uncertain state.

5. Method according to claim 3, characterized in that in said step (10-60) it is determined whether a current geographical position of said vehicle (V) corresponds to a presence of the latter (V) on a substantially straight section of traffic lane, and in the affirmative said differential (DR) is considered to be in an uncertain state, while in the negative said differential (DR) is considered to be in said blocked state.

6. A method according to any one of claims 2 to 5, characterized in that in said step (10-60) said predefined variation law consists of a monotonic increase followed by a monotonic decrease to zero.

7. A method according to any one of claims 1 to 6, characterized in that in said step (10-60), before determining whether said differential (DR) is in said unblocked state, one first determines whether said differential (DR) is in said blocked state, and in the negative determines whether said differential (DR) is in said unblocked state, while in the affirmative orders a placement of said differential (DR) in said unblocked state and then determines whether said differential (DR) is actually in said unblocked state.

8. Product computer program comprising a set of instructions which, when executed by processing means, is suitable for implementing the control method according to any one of claims 1 to 7, in a land vehicle (V) comprising i) a first half-train (DTI) equipped with a first wheel (RR1), ii) a second half-train (DT2) equipped with a second wheel (RR2) and a coupling device (DC1) which can be placed in connected and disconnected states in which said second wheel (RR2) is respectively connected and disconnected, and iii) an electric drive machine (MM1) coupled to a differential (DR) which can be placed in locked and unlocked states and coupled to said first (DTI) and second (DT2) half-trains, to control the disconnection of said second wheel (RR2).

9. Control device (DC4) for a land vehicle (V) comprising i) a first half-axle (DTI) equipped with a first wheel (RR1), ii) a second half-axle (DT2) equipped with a second wheel (RR2) and a coupling device (DC1) capable of being placed in connected and disconnected states in which said second wheel (RR2) is respec- ivically connected and disconnected, and iii) an electric motive machine (MM1) coupled to a differential (DR) which can be placed in blocked and unblocked states and coupled to said first (DTI) and second (DT2) half-trains, characterized in that it comprises at least one processor (PR1) and at least one memory (MD) arranged to perform the operations consisting, in the presence of a request to disconnect said second wheel (RR2), of determining whether said differential (DR) is in said unblocked state, and if so, authorizing said disconnection, or if not, ordering a placement of said differential (DR) in said unblocked state and then determining again whether said differential (DR) is actually in said unblocked state.

10. Land vehicle (V) comprising i) a first half-train (DTI) equipped with a first wheel (RR1), ii) a second half-train (DT2) equipped with a second wheel (RR2) and a coupling device (DC1) capable of being placed in connected and disconnected states in which said second wheel (RR2) is respectively connected and disconnected, and iii) an electric drive machine (MM1) coupled to a differential (DR) capable of being placed in locked and unlocked states and coupled to said first (DTI) and second (DT2) half-trains, characterized in that it further comprises a control device (DC4) according to claim 9.

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