EP4735286A1 - Control of an automotive hybrid powertrain in the transition between electric and hybrid propulsion of a hybrid-powered motor vehicle - Google Patents

Abstract

Automotive control software loadable on and executable by automotive electronic processing resources of a hybrid propulsion motor vehicle and designed, when executed, to cause the automotive electronic processing resources to become configured to control an automotive powertrain (MV) including a hybrid propulsion unit (P) and an automatic dual clutch transmission (T) interposed between the hybrid propulsion unit (P) and drive wheels (W) of the motor vehicle. The hybrid propulsion unit (P) comprises an internal combustion engine (MT) and a reversible electric motor (ME) and is electronically controllable to selectively operate in different operating modes comprising an electric mode, wherein the motor vehicle is driven only by the reversible electric motor (ME), and a hybrid mode, wherein the motor vehicle is driven by the internal combustion engine (MT), possibly assisted by the reversible electric motor (ME) in given operating conditions of the motor vehicle. The automatic dual clutch transmission (T) comprises: a servo-controlled gearbox electronically controllable to engage and disengage the gears corresponding to the various speeds; and a dual servo-controlled clutch (Ci, C2) interposed between the gearbox and the internal combustion engine and electronically controllable to couple and uncouple the gearbox and the internal combustion engine (MT). The automatic dual clutch transmission (T) comprises two distinct gear groups or branches, one defining an even gear branch (ST2) and one defining an odd gear branch (STi). The reversible electric motor (ME) is mechanically coupled to the drive wheels via one of the two gear groups. The automotive control software is designed, when executed, to cause the automotive electronic processing resources to become configured to: during operation of the hybrid propulsion unit (P) in electric mode (10), calculate (12- 13) gear pairs to be used in the electric mode and gear pairs to be used in the hybrid mode for use if a transition of the hybrid propulsion unit (P) from the electric mode to the hybrid mode is requested; and control (14-16) the automatic dual clutch transmission (T) so that it operates based on the gear pairs calculated in the respective operating modes of the hybrid propulsion unit (P). The automotive control software is designed, when executed, to cause the automotive electronic processing resources to become configured to: if a transition of the hybrid propulsion unit from the electric mode to the hybrid mode is requested (17), calculate (18) a sequence of transition gear pairs for transition between the gear pair used in the electric mode and the gear pair calculated for use in the hybrid mode to guarantee a continuity of torque delivered to the drive wheels (W) of the motor vehicle; and engage (20) the sequence of transition gear pairs for transition between the gear pair used in the electric mode and the gear pair calculated for use in the hybrid mode so that the motor vehicle passes from the electric mode to the hybrid mode (21).

Description

CONTROL OF AN AUTOMOTIVE HYBRID POWERTRAIN IN THE TRANSITION BETWEEN ELECTRIC AND HYBRID PROPULSION OF A HYBRID-POWERED MOTOR VEHICLE

CROSS-REFERENCE TO RELATED APPLICATIONS

This Patent Application claims priority from Italian Patent Application No. 102023000013674 filed on June 30, 2023, the entire disclosure of which is incorporated herein by reference.

TECHNICAL FIELD OF THE INVENTION

The present invention relates, generally, to the area of controlling gear pairs of a hybrid motor vehicle, particularly controlling an automotive hybrid powertrain in the transition between electric and hybrid propulsion of a hybrid-powered motor vehicle, even more particularly controlling gear pairs in the transition from the electric mode, wherein propulsion is only provided by a reversible electric motor of the hybrid propulsion motor vehicle, to the hybrid mode, wherein propulsion is provided by an internal combustion heat engine and, where appropriate, by the reversible electric motor.

The present invention relates, generally, to the field of hybrid propulsion motor vehicles, i.e. equipped with an internal combustion engine and an electric motor or reversible electric motor, both of the traditional type, in which the electric batteries are recharged with the aid of internal combustion engines, and of the so-called plug-in type (PHEV, Plug-in Hybrid Electric Vehicle), in which the electric batteries can be recharged even without the aid of internal combustion engines, using external electrical energy sources that can be electrically connected to the electric batteries via wired or wireless connections.

In particular, and without any loss of generality, the present invention relates to the area of hybrid propulsion motor vehicles with dual clutch transmission (DCT) and equipped with a reversible electric motor connected to a half-gearbox, for example, the one for engaging or disengaging even gears.

The present invention relates to automotive control software for controlling an automotive powertrain of a hybrid propulsion motor vehicle, in particular for controlling gear pairs in the transition from electric to hybrid mode. The present invention applies to any type of road motor vehicle, whether it is used for the transport of people, such as a car, bus, camper van, etc., or for the transport of goods, such as an industrial motor vehicle (truck, trailer truck, articulated lorry, etc.) or light or medium-heavy commercial vehicle (van, covered body vehicle, cab vehicle, etc.).

STATE OF THE ART

As is well known, automated or autonomous driving motor vehicles, in particular hybrid propulsion motor vehicles, are equipped with one or more automotive powertrains of the type shown schematically in Figure 1, indicated by the reference MV; in particular, the powertrain MV in Figure 1 comprises a propulsion unit P of any type (internal combustion, electric, hybrid), in this case hybrid, and an automatic or servo-actuated transmission (drivetrain or driveline) T interposed between the propulsion unit P and the drive wheels W of the hybrid propulsion motor vehicle, in particular, to transfer the mechanical power generated by the propulsion unit P to the drive wheels W. In particular, the transmission T is (and without any loss of generality) a Dual Clutch Transmission (DCT), as shown in Figure 1. The hybrid propulsion unit P comprises an internal combustion engine MT and a reversible electric motor ME and is electronically controllable to selectively operate in different operating modes comprising an electric mode, wherein the motor vehicle is driven by the reversible electric motor ME alone, and a hybrid mode, wherein the motor vehicle is driven by the internal combustion engine MT, possibly assisted by the reversible electric motor ME in given operating conditions of the motor vehicle. The automatic dual clutch transmission T comprises:

- a servo-controlled gearbox electronically controllable to engage and disengage the gears corresponding to the various speeds, in particular odd gears STi and even gears ST2; and

- a dual servo-controlled clutch Ci, C2 (in particular, controlled by an associated, electrically or electro-hydraulically controlled actuator, as well as by a plurality of electrically or electro-hydraulically controlled actuators, not shown) interposed between the gearbox and the internal combustion engine MT and electronically controllable to couple and uncouple the gearbox and the internal combustion engine MT.

The transmission T comprises two distinct gear groups or branches, one defining an even gear branch ST2 (forward as well as reverse), associated with the clutchC2, and one defining an odd gear branch STi, associated with the clutch Ci. In addition, the reversible electric motor ME is mechanically coupled to the drive wheels W via one of the two gear groups, in this case to the gear group defining the even gear branch ST2. Moreover, the reversible electric motor ME helps synchronize speeds on the even gear branch ST2 during gear engagement and disengagement.

It should be noted that, in the electric mode, the automatic dual clutch transmission T is designed to operate based on gear pairs, each comprising an active engaged gear that is involved in the propulsion of the motor vehicle (in particular, the even gears ST2), and a passive engaged gear that is not involved in the propulsion of the motor vehicle (in particular, the odd gears STi); in the hybrid mode, in which the internal combustion engine MT is started, the automatic dual clutch transmission T is designed to operate based on gear pairs wherein both the odd gears STi and the even gears ST2 contribute to the propulsion of the motor vehicle.

The powertrain MV is electronically controlled by a set of automotive electronic control units communicating with each other via automotive communication networks such as high-speed CAN, also known as C-CAN, a FlexRAy or others, and are dedicated to the electronic control of respective electronically controllable components of powertrains. In particular, the propulsion unit P is electronically controlled by a first electronic engine control unit, known as the Engine Control Module, ECM (not shown), whereas the transmission T is electronically controlled by a second electronic control unit, known as the Automatic Transmission Module, ATM (not shown). In particular, the ECM and ATM are designed to communicate with an on-board computer (not shown) programmed to receive, via the automotive communication network, quantities indicative of the operating conditions of on-board systems/components of the motor vehicle, such as the powertrain MV, one or more batteries, the various manual controls such as the accelerator pedal, brake pedal, handbrake, etc., and to control the operation of the powertrain MV accordingly. In a different embodiment, not shown, the ECM and ATM can be integrated into a single electronic control unit performing the functions of both.

OBJECT AND SUMMARY OF THE INVENTION

The Applicant noted that the solutions according to the prior art are improvable. In particular, with reference to Figure 2, the Applicant noted that, when a transition from the electric to the hybrid mode is requested, the known automotive control systems, integrated in the vehicle and on which automotive control software is loaded, are designed to implement logic according to which the following operations are performed:

- during operation of the hybrid propulsion unit P in the electric mode (block 1), calculating (blocks 2-4) gear pairs to be used in the electric mode and gear pairs to be used in the hybrid mode for use if a transition of the hybrid propulsion unit from the electric mode to the hybrid mode is requested;

- controlling (blocks 5-8) the automatic dual clutch transmission so that it operates based on the gear pairs calculated in the respective operating modes of the hybrid propulsion unit P, in particular following a request for hybrid operation.

The Applicant noted that, during transition from the electric mode to the hybrid mode, the ATM is configured, when running specific software installed and executable thereon, to select a gear pair which does not optimize the driveability of the manoeuvre and may lead to poor driving comfort for the driver of the motor vehicle, in particular in the event of acceleration of the motor vehicle, "gaps" in torque on the ground, "leaks" in rpm of the combustion engine and the like.

These situations are shown by way of example in the diagram in Figure 3, in which it can be seen a drop in acceleration (indicated with the reference A in the diagram and relating to a longitudinal accelerometer profile) during transition from the electric mode to the hybrid mode due to the simultaneous gear engagement on both odd STi and even ST2 gear branches (whose speeds are indicated in Figure 3 with the references C and B, respectively) caused by the temporary unavailability of gears engaged on both gear branches. Specifically, in Figure 3, the starting gears are the fourth on the even gear branch ST2 and the fifth on the odd gear branch STi and the end gears are the sixth on the even gear branch ST2 and the seventh on the odd gear branch STi.

Therefore, the object of the present invention is to optimize the management of the transition between the electric and hybrid modes without loss in responsiveness of the motor vehicle and traction during gear shifts, thus providing the driver with the best response feeling.

Therefore, the object of the present invention is to provide automotive control software for controlling an automotive powertrain of a hybrid propulsion motor vehicle, in particular for controlling gear pairs in the transition from electric to hybrid mode, allowing the problems afflicting the solutions of the prior art to be at least partially solved.

According to the present invention, automotive control software for controlling an automotive powertrain of a hybrid propulsion motor vehicle, in particular for controlling gear pairs in the transition from electric to hybrid mode, is provided as claimed in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 schematically shows a powertrain of a hybrid propulsion, automated or autonomous driving vehicle.

Figure 2 shows a block diagram of a known type of gear selection and gear transition management logic.

Figure 3 shows the time course of the speeds of the internal combustion engine, of the speeds associated with the even and odd gear branches, and the longitudinal acceleration of the hybrid propulsion motor vehicle as seen in known automotive control systems.

Figure 4 shows a block diagram of a gear selection and gear transition management logic according to the present invention.

Figure 5 shows the time course of the speeds of the internal combustion engine, of the speeds associated with the even and odd gear branches, and the longitudinal acceleration of the hybrid propulsion motor vehicle as a result of the application of the gear selection and gear transition management logic according to the present invention.

Figure 6 shows the time course of the speeds of the internal combustion engine, of the speeds associated with the even and odd gears, and the time course of the torques associated with the even and odd gears according to the logic of the present invention.

DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

The present invention will now be described in detail with reference to the attached figures in order to allow a skilled person to implement it and use it. Various modifications to the described embodiments will be readily apparent to those skilled in the art and the general principles described may be applied to other embodiments and applications without however departing from the protective scope of the present invention as defined in the appended claims. Therefore, the present invention should not be regarded as limited to the embodiments described and illustrated herein but should be allowed the broadest protection scope consistent with the features described and claimed herein.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning commonly understood by one of ordinary skill in the art to which the invention belongs. In case of conflict, the present specification, including the definitions provided, will control. Furthermore, the examples are provided for illustrative purposes only and as such should not be construed as limiting.

In particular, the block diagrams included in the attached figures and described below are not to be understood as a representation of the structural features, i.e. construction restrictions, but must be understood as a representation of functional features, i.e. intrinsic properties of the devices defined by the effects obtained, that is to say functional restrictions, which can be implemented in different ways, so as to protect the functionalities thereof (operational capability).

In order to facilitate the understanding of the embodiments described herein, reference will be made to some specific embodiments and a specific language will be used to describe the same. The terminology used herein is used for the purpose of describing particular embodiments only and is not intended to limit the scope of the present invention.

In summary, the aim of the present invention is to optimize the gear shift management during the start-up of the internal combustion engine of the motor vehicle, particularly by applying a limitation on the passive and active gears calculated for hybrid operation based on the passive and active gears engaged during electric operation.

With reference to Figure 4, the present invention relates to automotive control software loadable on and executable by automotive electronic processing resources (not shown, for example an automotive Electronic Control Unit, ECU, of the hybrid propulsion motor vehicle) of a hybrid-powered motor vehicle and designed, when executed, to cause the automotive electronic processing resources to become configured to control an automotive powertrain. In particular, in the following it is assumed, without any loss of generality, that the powertrain, as well as any other components of the hybrid propulsion motor vehicle described with reference to Figure 1, are similar to those described with reference to Figure 1, and therefore the same references are given below, unless otherwise stated, for any components of the hybrid propulsion motor vehicle described with reference to Figure 1.

In particular, as shown in Figure 4, the automotive control software is designed, when executed, to cause the automotive electronic processing resources to become configured to:

- during operation of the hybrid propulsion unit P in the electric mode (block 10), calculate (blocks 12-13) gear pairs to be used in the electric mode and gear pairs to be used in the hybrid mode for use if a transition of the hybrid propulsion unit P from the electric mode to the hybrid mode is requested; and

- control (blocks 14-16) the automatic dual clutch transmission T so that it operates based on the gear pairs STi, ST2 calculated in the respective operating modes of the hybrid propulsion unit P.

In particular, the automotive control software is designed, when executed, to cause the automotive electronic processing resources to become configured to:

- during operation of the hybrid propulsion unit in electric mode (block 10) with a given gear pair, check (block 15) whether the gear pair calculated for use in the hybrid mode of the hybrid propulsion unit meets a condition of admissibility depending on the gear pair STi, ST2 used in the electric mode and that is indicative of the fact that the gear pair STi, ST2 calculated for use in the hybrid mode guarantees a continuity of torque delivery to the drive wheels W of the motor vehicle if a transition of the hybrid propulsion unit P from the electric mode to the hybrid mode is requested; and

- if the gear pair STi, ST2 calculated for use in the hybrid mode of the hybrid propulsion unit meets the condition of admissibility, validate (block 16) the gear pair STi, ST2 calculated for use in the hybrid mode of the hybrid propulsion unit if a transition of the hybrid propulsion unit P from the electric mode to the hybrid mode is requested.

Furthermore, the automotive control software is designed, when executed, to cause the automotive electronic processing resources to become configured, if the gear pair calculated for use in the hybrid mode of the hybrid propulsion unit P does not meet the condition of admissibility, to calculate (block 15) a different gear pair STi, ST2 for use in the hybrid mode of the hybrid propulsion unit P if a transition of the hybrid propulsion unit P from the electric mode to the hybrid mode is requested. In other words, the automotive electronic processing resources are designed to operate a calculated limitation on the gear pair STi, ST2, for example by limiting superiorly or inferiorly the gears STi, ST2 to be engaged on the respective gear branch (whether odd or even STi, ST2) in the hybrid mode, so as to prevent the hybrid propulsion motor vehicle from losing traction while driving.

It should be noted that the condition of admissibility is defined by the fact that the gear pair calculated for use in the hybrid mode of the hybrid propulsion unit P belongs to a corresponding range of admissibility values. In particular, the admissibility condition is defined by the fact that the gear pair currently used in the electric mode of the hybrid propulsion unit P is associated with a corresponding range of admissibility values for the gear pair calculated for use in the hybrid mode of the hybrid propulsion unit P.

In order to calculate (block 15) a different gear pair to be used in the hybrid mode of the hybrid propulsion unit, if a transition of the hybrid propulsion unit P from the electric mode to the hybrid mode is requested, the automotive control software is further designed, when executed, in case the gear pair calculated for use in the hybrid mode of the hybrid propulsion unit does not meet the condition of admissibility, to cause the automotive electronic processing resources to become configured to vary (block 15) the calculated gear pair STi, ST2 so that it falls within the range of admissibility values associated with the corresponding gear pair STi, ST2 currently used in the electric mode of the hybrid propulsion unit P.

By way of example, according to one aspect of the present invention, the automotive electronic processing resources are designed to perform the aforementioned limitation on the gear pair calculated based on the logic summarized in Table 1 below:

Table 1 In other words, assuming the gear pair STi, ST2 currently used in the electric mode (i.e., the starting or initial gear pair STi, ST2), the automotive electronic processing resources are designed to limit superiorly or inferiorly the calculated gear pair STi, ST2 so as to significantly reduce the negative effect on driving comfort of the reduction in traction of the motor vehicle when switching from the electric to the hybrid mode (i.e., after the start-up of the internal combustion engine MT).

By way of example, with reference to Figure 5, during transition from the electric to the hybrid mode, in particular with the starting engaged gear pair STi, ST24-5 (i.e., in the electric mode), the automotive electronic processing resources are designed to limit the selectable gear STi, ST2 inferiorly to the third gear and superiorly to the fifth gear (as also shown in Table 1), thus preventing gear engagement on the even branch ST2 which would use the reversible electric motor ME in the synchronization and engagement of the new gear ratio STi, ST2, disconnecting it from the drive wheels W and causing a “gap” in the traction that is then visible in the accelerometer profile A in Figure 3 and causing a loss of comfort for the driver of the motor vehicle. In other words, the present invention allows a smooth and gradual transition from the electric mode to the hybrid mode without any loss in traction of the hybrid propulsion motor vehicle.

Referring collectively to Figures 4 and 6, the automotive control software is further designed, when executed, to cause the automotive electronic processing resources also to become configured to:

- if a transition of the hybrid propulsion unit from the electric mode to the hybrid mode is requested (block 17), calculate (blocks 18-19) a sequence of gear pairs STi, ST2 for transition between the gear pair used in the electric mode and the gear pair calculated for use in the hybrid mode to guarantee a continuity of torque delivered to the drive wheels W of the motor vehicle;

- engage (block 20) the sequence of transition gear pairs for transition between the gear pair STi, ST2 used in the electric mode and the gear pair STi, ST2 calculated for use in the hybrid mode so that the motor vehicle passes from the electric mode to the hybrid mode (block 21).

In particular, the sequence of transition gear pairs comprises a starting gear pair STi, ST2 for use when a transition of the hybrid propulsion unit from the electric mode to the hybrid mode is requested; moreover, in order to calculate (blocks 18-19) a sequence of transition gear pairs for transition between the gear pair STi, ST2 used in the electric mode and the gear pair STi, ST2 calculated for use in the hybrid mode such as to guarantee a continuity of torque delivered to the drive wheels W of the motor vehicle if a transition of the hybrid propulsion unit from the electric mode to the hybrid mode is requested, the automotive control software is designed, when executed, to cause the automotive electronic processing resources to become configured to carry out an inertial start-up (also known as clutch start) of the internal combustion engine MT using the pair associated with the gear branch that is not connected to the reversible electric motor ME, in this case the gear pair associated with the even gear branch ST2.

With reference to Figure 6, by way of non-limiting example, the hybrid propulsion motor vehicle initially operates in the electric mode, for example with starting engaged gears STi, ST2 2-5.

With reference to Figure 6, the aforementioned starting phase is shown in the Startup section, i.e., the clutch start, in which the clutch Ci is closed to allow the engine revolutions of the internal combustion engine MT to increase (as can also be seen from the trend of chart A”, representing the speed of the internal combustion engine MT); here the reversible electric motor ME is able to compensate for the torque to the drive wheels W to ensure that the driver does not perceive "gaps" in traction caused by gear shifting. As shown in Figure 6, the starting engaged gears STi, ST2 are 2-5, and the gear STi in the hybrid mode that is desired to be engaged is the third gear.

In order to engage (block 20) the sequence of transition gear pairs for transition between the gear pair used in the electric mode and the gear pair calculated for use in the hybrid mode so that the motor vehicle passes from the electric mode to the hybrid mode (block 21), the automotive control software is designed, when executed, to cause the automotive electronic processing resources to become configured to carry out a gear shift on the gear branch connected to the reversible electric motor ME, in this case the even gear branch ST22 (in Figure 6, to shift from second to fourth) so as to transmit the mechanical power from the internal combustion engine MT to the drive wheels W of the motor vehicle upon completion of start-up of the internal combustion engine MT. By way of example, with reference to Figure 6, the aforementioned gear shift phase is shown in the Transition section, in particular the EV-HYBi section, of the diagram in Figure 6. In particular, in this phase, traction on the ground is ensured by closure of the clutch Ci with the fifth gear ratio on the odd gear branch STi; subsequently, a so-called "clutch crossing" occurs, i.e., a situation in which, following the engagement of the fourth gear on ST2, there is a traction transition from fifth gear to fourth gear.

Subsequently, in order to engage (block 20) the sequence of transition gear pairs for transition between the gear pair used in the electric mode and the gear pair calculated for use in the hybrid mode so that the motor vehicle passes from the electric mode to the hybrid mode (block 21), the automotive control software is designed, when executed, to cause the automotive electronic processing resources to become configured to carry out a gear shift on the gear branch not connected to the reversible electric motor ME, in this case the odd gear branch ST (in Figure 6, to shift from third to fifth). In this phase, torque to the ground is ensured by closure of the clutch C2 with the fourth gear ratio engaged on the even gear branch ST2.

Again, by way of example, the aforementioned gear shift phase is shown in the Transition section in Figure 6, in particular the EV-HYB2 section of the diagram in Figure 6. Subsequently, a so-called "clutch crossing" occurs, i.e., a situation in which, following the engagement of the third gear on STi, there is a traction transition from fourth gear to third gear.

Once the gear shift has been made on the odd gear branch STi described above, and once the subsequent "clutch crossing" from fourth to third gear has been made, as shown in Figure 6, the motor vehicle has completed the transition phases, and transition from electric to hybrid mode, with gear engagement on the desired odd and even branches STi, ST2, can be considered to have occurred (section HYB in Figure 5).

On the basis of the above description, the advantages made possible by the present invention are evident.

In particular, the present software prevents loss of traction due to gear shifts when switching from electric to hybrid mode, by optimizing the selection of even and odd gears in the transient ignition of the internal combustion engine.

Claims

1. Automotive control software loadable on and executable by automotive electronic processing resources of a hybrid propulsion motor vehicle and designed to cause, when executed, the automotive electronic processing resources to become configured to control an automotive powertrain (MV) including a hybrid propulsion unit (P) and an automatic dual clutch transmission (T) interposed between the hybrid propulsion unit (P) and drive wheels (W) of the motor vehicle; the hybrid propulsion unit (P) comprises an internal combustion engine (MT) and a reversible electric motor (ME) and is electronically controllable to selectively operate in different operating modes comprising an electric mode, wherein the motor vehicle is driven only by the reversible electric motor (ME), and a hybrid mode, wherein the motor vehicle is driven by the internal combustion engine (MT), possibly assisted by the reversible electric motor (ME) in given operating conditions of the motor vehicle; the automatic dual clutch transmission (T) comprises:

- a servo-controlled gearbox electronically controllable to engage and disengage the gears corresponding to the various speeds; and

- a dual servo-controlled clutch (Ci, C2) interposed between the gearbox and the internal combustion engine and electronically controllable to couple and uncouple the gearbox and the internal combustion engine (MT), the automatic dual clutch transmission (T) comprises two distinct gear groups or branches, one defining an even gear branch (ST2) and one defining an odd gear branch (STi), the reversible electric motor (ME) is mechanically coupled to the drive wheels via one of the two gear groups, the automotive control software is designed, when executed, to cause the automotive electronic processing resources to become configured to:

- during operation of the hybrid propulsion unit (P) in electric mode (10), calculate (12-13) gear pairs to be used in the electric mode and gear pairs to be used in the hybrid mode for use if a transition of the hybrid propulsion unit (P) from the electric mode to the hybrid mode is requested; and - control (14-16) the automatic dual clutch transmission (T) so that it operates based on the gear pairs calculated in the respective operating modes of the hybrid propulsion unit (P), characterized in that the automotive control software is designed, when executed, to cause the automotive electronic processing resources to become configured to:

- if a transition of the hybrid propulsion unit from the electric mode to the hybrid mode is requested (17), calculate (18) a sequence of transition gear pairs for transition between the gear pair used in the electric mode and the gear pair calculated for use in the hybrid mode to guarantee a continuity of torque delivered to the drive wheels (W) of the motor vehicle;

- engage (20) the sequence of transition gear pairs for transition between the gear pair used in the electric mode and the gear pair calculated for use in the hybrid mode so that the motor vehicle passes from the electric mode to the hybrid mode (21).

2. The automotive control software according to claim 1, wherein the sequence of transition gear pairs comprises a starting gear pair for use when a transition of the hybrid propulsion unit (P) from the electric mode to the hybrid mode is requested, and wherein in order to calculate (18) a sequence of transition gear pairs for transition between the gear pair used in the electric mode and the gear pair calculated for use in the hybrid mode such as to guarantee a continuity of torque delivered to the drive wheels (W) of the motor vehicle if a transition of the hybrid propulsion unit (P) from the electric mode to the hybrid mode is requested, the automotive control software is designed, when executed, to cause the automotive electronic processing resources to become configured to carry out an inertial start-up of the internal combustion engine (MT) using the pair associated with the gear branch that is not connected to the reversible electric motor (ME).

3. The automotive control software according to claim 2, wherein, in order to engage (20) the sequence of transition gear pairs for transition between the gear pair used in the electric mode and the gear pair calculated for use in the hybrid mode so that the motor vehicle passes from the electric mode to the hybrid mode (21), the automotive control software is designed, when executed, to cause the automotive electronic processing resources to become configured to carry out a gear shift on the gear branch connected to the reversible electric motor (ME) to transmit the mechanical power to the drive wheels (W) of the motor vehicle upon completion of start-up of the internal combustion engine (MT).

4. The automotive control software according to claim 3, wherein, in order to engage (20) the sequence of transition gear pairs for transition between the gear pair used in the electric mode and the gear pair calculated for use in the hybrid mode so that the motor vehicle passes from the electric mode to the hybrid mode (21), the automotive control software is designed, when executed, to cause the automotive electronic processing resources to become configured to carry out a gear shift on the gear branch not connected to the reversible electric motor (ME).

5. The automotive control software according to any one of the preceding claims, and designed, when executed, to cause the automotive electronic processing resources to become configured to:

- during operation of the hybrid propulsion unit in electric mode with a given gear pair (15), check whether the gear pair calculated for use in the hybrid mode of the hybrid propulsion unit meets a condition of admissibility depending on the gear pair used in the electric mode and that is indicative of the fact that the gear pair calculated for use in the hybrid mode guarantees a continuity of torque delivery to the drive wheels of the motor vehicle if a transition of the hybrid propulsion unit (P) from the electric mode to the hybrid mode is requested; and

- if the gear pair calculated for use in the hybrid mode of the hybrid propulsion unit meets the condition of admissibility, validate (16) the gear pair calculated for use in the hybrid mode of the hybrid propulsion unit if a transition of the hybrid propulsion unit (P) from the electric mode to the hybrid mode is requested.

6. The automotive control software according to claim 5, further designed, when executed, to cause the automotive electronic processing resources to become configured, if the gear pair calculated for use in the hybrid mode of the hybrid propulsion unit (P) does not meet the condition of admissibility, to calculate (15) a different gear pair for use in the hybrid mode of the hybrid propulsion unit (P) if a transition of the hybrid propulsion unit (P) from the electric mode to the hybrid mode is requested.

7. The automotive control software according to claim 5 or 6, wherein the condition of admissibility is defined by the fact that the gear pair calculated for use in the hybrid mode of the hybrid propulsion unit (P) belongs to a corresponding range of admissibility values.

8. The automotive control software according to claim 7, wherein the admissibility condition is defined by the fact that the gear pair currently used in the electric mode of the hybrid propulsion unit (P) is associated with a corresponding range of admissibility values for the gear pair calculated for use in the hybrid mode of the hybrid propulsion unit (P).

9. The automotive control software according to claim 8, when dependent on claim 6, wherein, in order to calculate a different gear pair to be used in the hybrid mode of the hybrid propulsion unit (P), if a transition of the hybrid propulsion unit from the electric mode to the hybrid mode is requested, the automotive control software is further designed, when executed in case the gear pair calculated for use in the hybrid mode of the hybrid propulsion unit does not meet the condition of admissibility, to cause the automotive electronic processing resources to become configured to vary (15) the calculated gear pair so that it falls within the range of admissibility values associated with the corresponding gear pair currently used in the electric mode of the hybrid propulsion unit (P).

10. A hybrid propulsion motor vehicle comprising automotive electronic processing resources on which an automotive control software according to any one of the claims 1-9 can be stored and executed.