METHOD AND DEVICE FOR ASSISTING A DRIVER OF A PARALLEL HYBRID VEHICLE WITH A MANUAL TRANSMISSION BY SUGGESTING AN OPTIMAL POSITION, AS WELL AS VEHICLE

Description

Technical field of the invention

[0001] The invention relates to vehicles which include a so-called parallel hybrid transmission chain, comprising at least one drive machine and a thermal engine coupled to a clutch and a manual gearbox, and more specifically to driver assistance for such vehicles. State of the art

[0002] It should be noted that the invention relates to parallel hybrid drive systems in which an electric drive unit is capable of driving either the same drive train as that driven by the internal combustion engine if its connection to this train is located downstream of the gearbox, or a different drive train than the one driven by the internal combustion engine. Furthermore, the invention relates not only to hybrid electric vehicles (HEVs) but also to plug-in hybrid electric vehicles (PHEVs).

[0003] Currently, almost all parallel hybrid transmission systems are automated (i.e., with a robotized gearbox). This allows the driver to choose the transmission mode (electric and / or thermal), to manage the clutch of the internal combustion engine and the coupling of the electric motor, and to manage the transmission (selection and engagement of the gear ratio between the internal combustion engine and the wheels of the associated axle) by means of an algorithm that interprets the driver's intent based, in particular, on the vehicle's speed, the accelerator pedal depressment, and the brake pedal depressment.

[0004] Since this type of automated transmission is quite expensive, the robotized gearbox can be replaced with a manual gearbox controlled by a gear lever. The selected position allows the driver to choose between, on the one hand, so-called "thermal" gears, and on the other hand, so-called "electric" gears and a neutral position on a neutral line. This allows for the implementation of an electric operating mode for the vehicle without additional driver intervention and without the need for an actuator or a specific algorithm. In addition to reducing the vehicle's cost, this replacement allows the transmission to offer the main features of a hybrid vehicle with a robotized gearbox (including ZEV driving (zero emissions of pollutants and CO2), reduced fuel consumption, and a power boost).

[0005] However, in practice, due to the large number of different positions the gear selector can be in, some drivers find it difficult to choose the electric or combustion engine gear that is best suited to their vehicle's current driving conditions. Consequently, the driver's choice may not be optimal, which can negatively impact vehicle performance and / or lead to increased fuel consumption.

[0006] Furthermore, a method conforming to the preamble of claim 1 is known from patent document EP-2574829-A1.

[0007] The invention is therefore intended, in particular, to improve the situation. Presentation of the invention

[0008] In particular, it proposes for this purpose an assistance method according to claim 1, intended to assist a driver of a vehicle comprising a parallel hybrid transmission chain including an electric drive machine associated with at least one rechargeable battery having a state of charge in progress (defined by an indicator), and a thermal engine coupled to a clutch and a manual type gearbox controlled by a gear lever whose position selected by the driver allows the selection of so-called thermal gears, and so-called electric gears and a neutral state on a neutral line.

[0009] This assistance process includes: a first step in which an optimal position for the gear lever is determined for a given instant as a function of the current state of load and a current speed of the vehicle, and a second step in which it is determined whether this determined optimal position should be offered to the driver, as a function of a setpoint torque to the wheels of the vehicle determined for this instant, a maximum torque that the driving machine can provide at this instant, and the position of the gear lever selected by the driver.

[0010] This allows us to assist the vehicle driver at every moment by indicating the optimal position of the gear lever to optimize the powertrain (or GMP) energy consumption / performance ratio when necessary.

[0011] According to the invention, in said second step, when said optimal position corresponds to an electrical ratio and said determined setpoint torque is less than said maximum torque that said drive machine can provide, it is determined whether said selected position is identical to said optimal position, and if so, said optimal position is not offered to said driver, while if not, it is determined whether said gear lever is in a neutral state while said clutch is not in an open position, and if so, said optimal position is not offered to said driver, while if not, said optimal position is offered to said driver.

[0012] The assistance method according to the invention may include other features which may be taken separately or in combination, and in particular: in the second step, when the determined optimal position corresponds to an electrical ratio and the determined setpoint torque is greater than the maximum torque that the driving machine can provide, this optimal position may not be offered to the driver; in the second step, when the determined optimal position corresponds to a thermal ratio, it may be determined whether the selected position is identical to this optimal position, and if so, this optimal position is not offered to the driver, while if not, it is determined whether the gear lever is in a neutral state while the clutch is not in an open position, and if so, this optimal position is not offered to the driver, while if not, this optimal position is offered to the driver;in its second stage the optimal position can be proposed to the driver by displaying a message on at least one screen present in the vehicle and / or by broadcasting an audible message with at least one loudspeaker present in the vehicle; in its first stage either an optimal position corresponding to a thermal ratio can be determined when the state of charge is below a predefined charge threshold or when the state of charge is above this predefined charge threshold and the current speed is above a predefined speed threshold, or an optimal position corresponding to an electrical ratio can be determined when the state of charge is above this predefined charge threshold and the current speed is below this predefined speed threshold;In its first stage, an optimal position can be determined, corresponding to a thermal ratio as a function of the current speed and a value that represents a percentage of the vehicle's accelerator pedal being depressed.

[0013] The invention also provides an assistance device according to claim 7.

[0014] The invention also provides a vehicle according to claim 8, possibly of the automobile type. Brief description of the figures

[0015] Other features and advantages of the invention will become apparent upon examination of the detailed description below, and the accompanying drawings, in which: [ Fig. 1 ] schematically and functionally illustrates a vehicle comprising a parallel hybrid transmission chain and a supervisory computer equipped with an assistance device according to the invention, [ Fig. 2 ] schematically illustrates an example of a gear selector grid associated with a gear lever of a vehicle of the type shown on the figure 1 , And [ Fig. 3 ] schematically illustrates an example of an algorithm implementing an assistance method according to the invention. Detailed description of the invention

[0016] The invention aims in particular to provide an assistance method, and an associated DA assistance device, intended to assist the driver of a vehicle V with a parallel hybrid transmission chain comprising an electric drive machine MM, a thermal engine MT and a manual type gearbox BV.

[0017] In what follows, vehicle V is considered, by way of non-limiting example, to be an automobile. For example, a car. However, the invention is not limited to this type of vehicle. It relates to any type of land vehicle.

[0018] We have schematically represented on the figure 1 a vehicle V comprising a parallel hybrid transmission chain, a CA supervisory computer, and a DA assistance device according to the invention.

[0019] The transmission chain (parallel hybrid) includes a hybrid powertrain (or PWM) whose operation is supervised (or managed) by the CA supervisory computer, an EM clutch, a manual type BV gearbox, and an optional MC coupling / decoupling means.

[0020] The hybrid powertrain includes, in particular, a thermal engine MT, at least one electric drive unit MM, and at least one rechargeable battery BR.

[0021] Here, "thermal engine MT" refers to an engine that consumes fuel or chemicals.

[0022] The MT internal combustion engine includes a crankshaft (not shown) which is fixedly attached to a drive shaft in order to drive the latter in rotation.

[0023] The manual gearbox (BV) comprises at least one input (or primary) shaft designed to receive the torque produced by the internal combustion engine (MT) via the clutch (EM), and an output shaft designed to receive this torque via the input shaft in order to transmit it to a drive shaft to which it is coupled and which is indirectly coupled to the wheels (here, the front axle TV of the vehicle V), preferably via a front differential (DV). For example, the clutch (EM) comprises a flywheel fixedly attached to the engine shaft and a clutch disc fixedly attached to the input shaft of the gearbox (BV).

[0024] This EM clutch can be placed either in an open (or disengaged) position in which it totally decouples the MT internal combustion engine from the BV gearbox, or in a closed (or engaged) position in which it couples the MT internal combustion engine to the BV gearbox, or in an intermediate (or sliding) position in which it begins to decouple / couple the MT internal combustion engine from / to the BV gearbox.

[0025] The operation of this BV gearbox is controlled by an LV gear lever which is operated by the driver of vehicle V.

[0026] More specifically, this LV gear lever allows the driver to select, on the one hand, so-called thermal ratios, and, on the other hand, so-called electrical ratios and a neutral state on a neutral line LN.

[0027] We have schematically illustrated on the figure 2 an example of a gear selector grid associated with an LV gear lever of a V-type vehicle of the type illustrated on the figure 1 This sample shift pattern is adapted for a manual transmission (BV) with three odd-numbered gears (1, 3, and 5), three even-numbered gears (2, 4, and 6), and one reverse (thermal) gear (R). It also includes a neutral line (LN) providing access to a neutral position (N) of the manual transmission (BV), an electric forward gear (E1) with the drive unit (MM), and an electric reverse gear (E2) with the drive unit (MM). It should be understood that when the driver places the gear selector (LV) in position E1, this means the driver wants the transmission to operate in forward gear exclusively with the drive unit (MM). Similarly, when the driver places the gear selector (LV) in position E2, this means the driver wants the transmission to operate in reverse gear exclusively with the drive unit (MM).In all other positions, the driver wants the drive chain to work with the internal combustion engine MT, except when the gearbox BV is in a neutral state (or neutral position).

[0028] The drive machine MM is an electric machine or motor designed to provide torque to move the vehicle V, either alone or in conjunction with the internal combustion engine MT. To do this, it uses electrical energy stored in the rechargeable battery BR to which it is connected, possibly via an inverter (not shown).

[0029] For example, the rechargeable BR battery is of the low voltage type (e.g., approximately 220 V) or extra-low voltage type (e.g., 48 V). Its current state of charge ec (defined by an indicator) is known at all times by the CS monitoring computer.

[0030] The optional coupling / decoupling means MC can be used to couple / decouple the drive machine MM to a transmission shaft in order to transmit the torque it produces using electrical energy stored in the rechargeable battery BR. This transmission shaft drives the wheels of a train. This optional coupling / decoupling means MC could be, for example, a dog clutch mechanism, a clutch, or a hydraulic torque converter.

[0031] It should be noted that in the example of implementation illustrated, but not limited to, on the figure 1 The coupling / decoupling means MC is responsible for coupling / decoupling the drive unit MM to a drive shaft that is different from the one to which the internal combustion engine MT is coupled (via the clutch EM). This coupling / decoupling is shown here on the rear axle TR of the vehicle V, via a rear differential DR, as an illustrative example. However, in an alternative embodiment not shown, the coupling / decoupling means MC could be responsible for coupling / decoupling the drive unit MM to the drive shaft to which the internal combustion engine MT is coupled (via the clutch EM), downstream of the gearbox BV. In another alternative, the drive unit MM could be mounted at the rear wheels after the rear differential DR, without a reduction gear stage.

[0032] The transmission chain also includes an AD electric machine (starter or alternator-starter) which is coupled to the MT internal combustion engine, notably to start it during a start-up. As illustrated, but not limited to, on the figure 1 This AD electric machine can also be coupled to a BS auxiliary battery, for example of the very low voltage type (e.g., 12 V, 24 V or 48 V). But it could also be powered by the BR rechargeable battery.

[0033] Also, as illustrated but not limited to the image on the figure 1 , we can also provide a CV type DC / DC converter between the rechargeable battery BR and the service battery BS, in order to ensure the supply of the vehicle's on-board network V if the electric machine AD operates at a different voltage level.

[0034] As previously stated, the invention proposes to implement in vehicle V an assistance method intended to assist the driver of vehicle V in choosing the position of the gear lever LV.

[0035] Such a process can be implemented by a DA assistance device. In the non-limiting example illustrated on the figure 1 The power steering (PS) assistance system is part of the control unit (CU). This is because the CU manages the powertrain and therefore has access to many vehicle operating parameters. However, this is not mandatory. The PS assistance system could be integrated with the CU, either directly or indirectly. It could also be part of another control unit or device. In all cases, the PS assistance system includes at least one processor and at least one memory unit that work together, notably to determine the optimal position for the gear selector at a given moment, as will be discussed later.

[0036] The process, according to the invention, comprises first 10-40 and second 50-90 steps.

[0037] In the first step 10-40, on (the DA device) determines an optimal position po for the gear lever LV for the current moment, as a function of the current load state ec and the current speed vv of the vehicle V. These current load states ec and current speed vv are known at every moment by the CS supervisory computer.

[0038] For example, in this first step 10-40 on (the DA device) can determine an optimal position po which corresponds to a thermal ratio as a function of the current speed vv and a value which is representative of a percentage of the accelerator pedal PA of the vehicle V. This percentage of depressment is representative of the driver's intention regarding acceleration at the current moment.

[0039] Also for example, in this first step 10-40 on (the DA device) can either determine an optimal position po which corresponds to a thermal ratio when the state of charge ec is less than a predefined charge threshold s1, or when the state of charge ec is greater than this predefined charge threshold s1 and at the same time the current speed vv is greater than a predefined speed threshold s2, or determine an optimal position po which corresponds to an electrical ratio when the state of charge ec is greater than the predefined charge threshold s1 and at the same time the current speed vv is less than the predefined speed threshold s2.

[0040] For example, the load threshold s1 can be between approximately 1% and approximately 20% of the maximum load. Thus, the load threshold s1 could, for example, be equal to 5% of the maximum load.

[0041] Also, as an example, the speed threshold s2 can be between approximately 30 km / h and approximately 70 km / h. Thus, the speed threshold s2 can, for example, be equal to 50 km / h.

[0042] In the second step, 50-90, the DA device determines whether the optimal position po (determined in the first step, 10-40) should be offered to the driver of vehicle V, based on a setpoint torque cc at the wheels of vehicle V (this is the total torque to be supplied to all wheels), currently determined by the supervisory computer CA, a maximum torque c max that the drive unit MM can supply at that current instant, and the position pl of the gear lever LV selected by the driver. It should be noted that the maximum torque c max can vary over time due to the inherent characteristics of the drive unit MM, which generally has a constant torque phase (at low speed) followed by a constant power phase.

[0043] Thus, we can assist the driver of vehicle V at any moment by indicating the optimal position po of the LV gear lever in order to optimize the torque, energy consumption / performance of the GMP, when this proves useful.

[0044] The position pl of the LV gear lever is determined by at least one sensor coupled to the lever (LV), and preferably by two sensors CE and CS, as illustrated (non-exhaustively) on the figures 1 et 2 For example, a first sensor (or selection sensor) CS can be arranged to determine the selected position of the gear selector lever LV, and a second sensor (or engagement sensor) CE can be arranged to determine whether a thermal (1 to 6 or R) or electrical (E1 or E2) gear, or the neutral (N) position, is engaged or being engaged. To do this, these first CS and second CE sensors can measure percentages. They are then of the proportional type.

[0045] In the example illustrated, but not limited to the figure 2 : When the first sensor CS delivers a value between g = 0% and h%, it means that the reverse gear thermal ratio R or the reverse gear electrical ratio E2 has been selected; when the first sensor CS delivers a value between h% and i%, it means that thermal ratio no. 1 or the forward gear electrical ratio E1 or thermal ratio no. 2 has been selected; when the first sensor CS delivers a value between i% and j%, it means that thermal ratio no. 3 or the neutral state N or thermal ratio no. 4 has been selected; when the first sensor CS delivers a value between j% and k = 100%, it means that thermal ratio no. 5 or thermal ratio no. 6 has been selected; when the second sensor CE delivers a value between a = 0% and b%, it means that the reverse gear thermal ratio R or one of the odd thermal ratios (no. 1, 3 or 5) is engaged in the gearbox BV.When the second CE sensor delivers a value between c% and d%, it means that the reverse gear E2 or the forward gear E1 or neutral N is selected on the neutral line LN; when the second CE sensor delivers a value between e% and f = 100%, it means that one of the even thermal ratios (No. 2, 4 or 6) is engaged in the gearbox BV; when the second CE sensor delivers a value between b% and c% or between d% and e%, it means that no gear is engaged.

[0046] According to the invention, in the second step 50-90, when the optimal position po corresponds to an electrical ratio (here E1 or E2) and the determined setpoint torque cc is less than the maximum torque c max that the drive machine MM can supply, the device DA determines whether the position pl of the gear lever LV selected by the driver is identical to this optimal position po. If so, the device DA does not offer this optimal position po to the driver, as it is pointless to provide the driver with information likely to attract their attention when the position pl they selected is the same as the optimal position po just determined. Conversely, if the position is negative (cc > c max), the device DA determines whether the gear lever LV is in a neutral state N while the clutch EM is not in an open position ee (and is therefore in a closed or slipping position).If the driver is in neutral, the DA system does not offer the optimal position (po) to the driver. This is because if the driver shifts into neutral and releases the clutch pedal (i.e., clutch engaged or slipping during the transition), it means they do not wish to engage a gear (for example, for low-speed "Stop & Start" or to coast downhill), and in this case, the optimal position is no longer displayed. Conversely, if the driver is in negative, the DA system does offer the optimal position (po) to the driver. As soon as the driver depresses the clutch pedal again (clutch disengaged), it means they will want to engage a gear again (for example, to accelerate), and in this case, the optimal position is immediately re-displayed.

[0047] The position of the clutch (EM) is determined by a sensor coupled to the clutch (EM), which provides measurements to the control unit (CA). For example, such a sensor can be a proportional type. It is then configured to measure the percentage of clutch pedal (PE) depressed. In this case, the open position corresponds to a depressment between 0% and x1%, the sliding position corresponds to a depressment between x1% and x2%, and the closed position corresponds to a depressment between x2% and 100%. For example, and not limited to, x1 could be between 30% and 50% and x2 could be between 70% and 80%.

[0048] For example, in the second step 50-90, when the optimal position po corresponds to an electrical ratio (here E1 or E2) and the determined setpoint torque cc is greater than the maximum torque c max that the drive machine MM can supply, the device DA may not offer this optimal position po to the driver. This is because it is assumed that the drive machine MM will not be able to meet the current torque demand, and therefore it is pointless to offer the driver the option of selecting an electrical ratio.

[0049] For example, in the second step 50-90, when the optimal position po corresponds to a thermal ratio (here, numbers 1 to 6, or R), the DA device can determine if the position pl of the gear selector LV selected by the driver is identical to the optimal position po. If so, the DA device may not offer this optimal position po to the driver, as there is no point in providing the driver with information likely to attract their attention when the position pl they selected is the same as the optimal position po that was just determined. Conversely, if the position is negative, the DA device determines if the gear selector LV is in a neutral state N while the clutch EM is not in an open position ee (and is therefore in a closed or slipping position). If so, the DA device does not offer the optimal position po to the driver.Conversely, in the negative, on (the DA device) proposes the optimal position po to the driver.

[0050] It should be noted that in the second stage 50-90 on (the DA device) can propose the optimal position po to the driver by displaying a (or triggering the display of a) message on at least one EA screen present in the vehicle V and / or by broadcasting a (or triggering the broadcast of a) sound message with at least one speaker present in the vehicle V.

[0051] The EA screen, if used, may, for example, be part of the instrument panel or dashboard of vehicle V (in which case it may, for example, be part of the central instrument cluster), or it may be a section of the vehicle V's windshield located in front of the steering wheel and instrument panel and used by a head-up display. However, this screen could also be part of a communication device (such as a smartphone or tablet) belonging to the driver and temporarily present in vehicle V.

[0052] The speaker, if used, may be permanently installed in vehicle V or may be part of a communication device (such as a smartphone or tablet) belonging to the driver and temporarily present in vehicle V.

[0053] We have schematically illustrated on the figure 3 an example of an algorithm implementing the first 10-40 and second 50-90 steps of the assistance process described above.

[0054] In a first sub-step 10 of the first step, we (the DA device) perform a test to determine if the state of charge ec is greater than the predefined charge threshold s1.

[0055] In the negative (“no” - ec < s1), we (the DA device) determine in a second sub-step 20 of the first step an optimal position po (of the LV gear lever) which corresponds to a thermal ratio.

[0056] If affirmative ("yes" - ec > s1), we (the DA device) perform a test in a third sub-step 30 of the first step to determine if the current speed vv is below the predefined speed threshold s2.

[0057] In the negative (vv > s2), we (the DA device) determine in the second sub-step 20 of the first step an optimal position po (of the LV gear lever) which corresponds to a thermal ratio.

[0058] If so (vv < s2), we (the DA device) determine in a fourth sub-step 40 of the first step an optimal position po which corresponds to an electrical ratio.

[0059] Then, in a fifth sub-step 50 of the second step, on (the DA device) performs a test to determine if the setpoint torque cc which has just been determined by the supervisory computer CA is less than the maximum torque c max which the drive machine MM can provide.

[0060] In the negative (cc > c max), we (the DA device) decide in a sixth sub-step 60 of the second step not to propose the optimal position po determined to the driver.

[0061] On the other hand, if the affirmative (cc < c max), we (the DA device) perform a test in a seventh sub-step 70 of the second step in order to determine if the position pl of the LV gear lever selected by the driver is identical to the optimal position po determined in the second sub-step 20 or the fourth sub-step 40.

[0062] If so, we (the DA device) decide in a sixth sub-step 60 of the second step not to propose the optimal position po determined to the driver.

[0063] On the other hand, if the negative, we (the DA device) determine in an eighth sub-step 80 of the second step whether the gear lever LV is in a neutral state N while the clutch EM is in the closed or sliding position.

[0064] If so, we (the DA device) decide in a sixth sub-step 60 of the second step not to propose the optimal position po determined to the driver.

[0065] On the other hand, if the negative is true, we (the DA device) decide in a ninth sub-step 90 of the second step to propose the optimal position po determined to the driver.

[0066] It should be noted that on the figure 1The DA assistance system is schematically represented by a simple rectangle within the CA supervisory computer. However, as mentioned previously, this DA assistance system includes at least one processor, for example a digital signal processor (or DSP), and RAM to store instructions for this processor to implement part of the assistance process as described above, as well as possibly mass storage, particularly for storing data generated during all its calculations and processing (possibly intermediate) and measurements or information provided by vehicle equipment. Furthermore, in one embodiment, the DA assistance system could be part of a computer other than the CA supervisory computer. In another embodiment, the DA assistance system could comprise its own computer.In this case, the control unit 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. Furthermore, regardless of the control unit, it receives at least some measurements or operating parameters from vehicle V equipment for use in calculations or processing, possibly after shaping, demodulating, and / or amplifying them in a known manner. In addition, this control unit may also be associated with an input interface for receiving at least the measurements or operating parameters provided by vehicle V equipment, and an output interface, notably for transmitting its proposals for the optimal position of the gear selector lever.

[0067] One or more substeps of each of the first and second steps of the assistance process can be performed by different components. Thus, the assistance process can be implemented by a plurality of digital signal processors, RAM, mass storage, input interfaces, and output interfaces.

Claims

1. Method for assisting a driver of a vehicle (V) comprising a parallel hybrid transmission chain comprising i) a prime mover (MM) of the electric type and associated with at least one rechargeable battery (BR) having a current state of charge, and ii) a thermal engine (MT) coupled to a clutch (EM) and to a gearbox (BV) of the manual type and controlled by a gear lever (LV) whose position selected by said driver makes it possible to select so-called thermal gears, and so-called electric gears and a neutral state on a neutral line, this method comprising a) a first step (10-40) in which an optimal position for said gear lever (LV) is determined for a current instant as a function of said current state of charge and a current speed of said vehicle (V), and b) a second step (50-90) in which it is determined whether said determined optimal position must be proposed to said driver as a function of a setpoint torque at the wheels of said vehicle (V) determined for said current instant, of a maximum torque that can be provided said prime mover (MM) at said current time, and of said selected position, characterized in that in said second step (50-90) when said optimal position corresponds to an electrical gear and said determined setpoint torque is less than said maximum torque that said prime mover (MM) can provide, it is determined whether said selected position is identical to said optimal position, and if so, said optimal position is not proposed to said driver, while if not, it is determined whether said gear lever (LV) is in a neutral state while said clutch (EM) is not in an open position, and if so, said optimal position is not proposed to said driver, while if not, said optimal position is proposed to said driver.

2. Method according to claim 1, characterized in that in said second step (50-90) when said determined optimal position corresponds to an electrical gear and said determined setpoint torque is greater than said maximum torque that said prime mover (MM) can provide, said optimal position is not proposed to said driver.

3. Method according to one of claims 1 to 2, characterized in that in said second step (50-90) when said determined optimal position corresponds to a thermal ratio, it is determined whether said selected position is identical to said optimal position, and if so, said optimal position is not proposed to said driver, while if not, it is determined whether said gear lever (LV) is in a neutral state while said clutch (EM) is not in an open position, and if so, said optimal position is not proposed to said driver, while if not, said optimal position is proposed to said driver.

4. Method according to one of claims 1 to 3, characterized in that in said second step (50-90) said optimal position is proposed to said driver by displaying a message on at least one screen (EA) present in said vehicle (V) and / or by broadcasting an audible message with at least one loudspeaker present in said vehicle (V).

5. Method according to one of claims 1 to 4, characterized in that in said first step (10-40) either an optimal position corresponding to a thermal ratio is determined when said state of charge is lower than a predefined charge threshold or when said state of charge is higher than said predefined charge threshold and said current speed is higher than a predefined speed threshold, or an optimal position corresponding to an electrical ratio is determined when said state of charge is higher than said predefined charge threshold and said current speed is lower than said predefined speed threshold.

6. Method according to one of claims 1 to 5, characterized in that in said first step (10-40) an optimal position corresponding to a thermal ratio is determined as a function of said current speed and a value representative of a percentage of depression of an accelerator pedal of said vehicle (V).

7. Assistance device (DA) for assisting a driver of a vehicle (V) comprising a parallel hybrid transmission chain comprising i) a prime mover (MM) of the electric type and associated with at least one rechargeable battery (BR) having a current state of charge, and ii) a thermal engine (MT) coupled to a clutch (EM) and to a gearbox (BV) of the manual type and controlled by a gear lever (LV) whose position selected by said driver makes it possible to select so-called thermal gears, and so-called electric gears and a neutral state on a neutral line, said device comprising at least one processor and at least one memory cooperating together to determine an optimal position for said gear lever (LV) for a current instant as a function of said current state of charge and a current speed of said vehicle (V), and to determine whether said determined optimal position must be proposed to said driver as a function of a setpoint torque at the wheels of said vehicle (V) determined for said current instant, of a maximum torque that said prime mover (MM) can provide at said current instant, and of said selected position, characterized in that when said optimal position corresponds to an electrical ratio and said determined setpoint torque is less than said maximum torque that said prime mover (MM) can provide, the processor determines whether said selected position is identical to said optimal position, and if so the processor does not propose said optimal position to said driver, while if not the processor determines whether said gear lever (LV) is in a neutral state while said clutch (EM) is not in an open position, and if so the processor does not propose said optimal position to said driver, while if not the processor proposes said optimal position to said driver.

8. Vehicle comprising a parallel hybrid transmission chain comprising i) a prime mover (MM) of the electric type and associated with at least one rechargeable battery (BR) having a current state of charge, and ii) a thermal engine (MT) coupled to a clutch (EM) and to a gearbox (BV) of the manual type and controlled by a gear lever (LV) whose position selected by said driver makes it possible to select so-called thermal gears, and so-called electric gears and a neutral state on a neutral line, characterized in that it further comprises an assistance device (DA) according to claim 7.

9. Vehicle according to claim 8, characterized in that it is of the automobile type.