Method and device for managing the operation of a thermal engine in a hybrid motor vehicle equipped with a dog clutch gearbox

Abstract

The invention relates to a method for managing the operation of an internal combustion engine (2) of a motor vehicle (1) equipped with a dog-clutch gearbox (4) driven by the internal combustion engine (2) and at least one electric motor (3), said method being implemented by a computer device (100) installed on board the vehicle. The invention also relates to a device (100) implementing such a method, as well as a motor vehicle (1) comprising such a device. Figure for the abstract: 1

Description

Title of the invention: Method and device for managing the operation of a thermal engine in a hybrid motor vehicle equipped with a dog clutch gearbox Technical field of the invention

[0001] The present invention relates to the field of embedded computer and electronic systems in motor vehicles for managing their operation. The invention relates in particular to a method for managing the operation of an internal combustion engine in a motor vehicle equipped with a dog-clutch gearbox driven by the internal combustion engine and at least one electric motor, the method being implemented by an embedded computer system in the vehicle. The invention also relates to a device implementing such a method, as well as a motor vehicle incorporating such a device. The invention is applicable to motor vehicles such as motor land vehicles, particularly cars. Prior art

[0002] Certain hybrid motor vehicles (i.e., with a hybrid internal combustion and electric powertrain) are equipped with a dog-clutch gearbox that is jointly driven by an internal combustion engine and at least one electric motor, with one or more dog clutches of the gearbox being driven by the internal combustion engine while one or more others are driven by the electric motor. In such a vehicle, an action performed by the driver on the vehicle's accelerator pedal is therefore interpreted by the vehicle's computers in order to manage the operation of the gearbox, in particular according to an operating strategy that establishes a gearbox ratio based on a value of the vehicle's torque required, and that of the motors, in particular according to predetermined torque setpoints.

[0003] For example, in a situation where the driver accelerates, i.e. he presses the accelerator pedal fully, while the vehicle is traveling at a cruising speed of around 100 km / h, a computer managing the operation of the gearbox generally establishes an operating strategy which causes a dog clutch driven by the electric motor to engage, while the internal combustion engine which was driving a first dog clutch is forced to disengage and then engage a different dog clutch.

[0004] However, for performance reasons, we generally start by synchronizing the speed of the electric motor in order to engage it, then we disengage the internal combustion engine, then we synchronize its speed and then engage it on the different dog clutch. The problem that arises is that, during the electric motor's engagement phase, the internal combustion engine reaches its maximum operating point to meet the torque demand. However, as soon as the electric motor is engaged, the internal combustion engine must reduce its torque to disengage. This back-and-forth process creates a response delay, which the driver perceives as acceleration lag.

[0005] And obviously, the same problem occurs if it is a cruise control or any other computer in a driving assistance system that generates a command or instruction that reproduces a restart situation, i.e. a sudden request for strong acceleration. Summary of the invention

[0006] The invention aims to overcome these drawbacks. In particular, it aims to provide a solution for reducing the response time, which results in acceleration lag during a sudden and forceful acceleration request, in a hybrid vehicle equipped with a dog-clutch transmission. Through this means, the invention aims to improve the comfort and performance of hybrid vehicles equipped with dog-clutch transmissions.

[0007] In order to achieve these objectives, the invention relates, according to a first aspect, to a method for managing the operation of an internal combustion engine of a motor vehicle equipped with a dog-clutch gearbox driven by the internal combustion engine and at least one electric motor, said method being implemented by a computer device embedded in the vehicle and comprising the steps of: i. determine if a first condition is met, said first condition being met when it is established that a value of the torque of the requested vehicle increases beyond a pre-established threshold value; ii. obtain data characterizing an operating strategy for said gearbox which is established according to said value of the torque of the vehicle requested; iii. determine whether a second condition is met, said second condition being met when it is established that said strategy involves the engagement of a dog clutch of said gearbox which is driven by said electric motor and the disengagement of a dog clutch of said gearbox which is driven by said internal combustion engine; and iv. manage the operation of said thermal engine according to data characterizing a constant torque setpoint when it is established that said first condition and said second condition are met.

[0008] According to one variant, step iv) can be carried out as long as said dog clutching is not intervened.

[0009] According to another variant, said strategy can establish, in relation to at least one instant subsequent to the current instant, a ratio of said gearbox.

[0010] According to yet another variant, said torque setpoint can be established based on an initial torque value taken into account for the management of the operation of said internal combustion engine at the time when the increase in the value of the required vehicle torque occurs.

[0011] According to yet another variant, the threshold value can be between 800 Nm and 1500 Nm.

[0012] According to a second aspect, the invention relates to a device for managing the operation of a thermal engine of a motor vehicle equipped with a dog clutch gearbox driven by the thermal engine and at least one electric motor, the device comprising at least one information processing unit, including at least one processor, and a data storage medium, which are configured to implement a method as described above.

[0013] According to a third aspect, the invention relates to a computer program comprising program code instructions for the execution of the steps of a process as described above when said program is executed by at least one processor.

[0014] According to a fourth aspect, the invention relates to a medium usable in a computer on which a program as described above is recorded.

[0015] According to a fifth aspect, the invention relates to a motor vehicle which incorporates a device as described above. Brief description of the figures

[0016] Other features and advantages of the invention will become apparent from an examination of the detailed description below, and the accompanying figures, in which:

[0017] [Fig-1] is a schematic illustration of a motor vehicle according to the invention;

[0018] [Fig.2] is a functional diagram of a device according to the invention;

[0019] [Fig.3] is a flowchart of the steps of a process according to the invention;

[0020] [Fig.4] illustrates the operation of a motor vehicle according to the prior art; and

[0021] [Fig.5] illustrates the implementation of at least one step of the process according to the invention. Detailed description of the invention

[0022] Figure 1 schematically illustrates a motor vehicle 1 according to the invention. It is a hybrid vehicle comprising an internal combustion engine 2 and at least one electric motor 3 which jointly drive a dog clutch gearbox 4. Thus, some dog clutches of the gearbox 4 are driven by the internal combustion engine 2, while other dog clutches are driven by the electric motor 3. According to a mode of In the preferred configuration, the internal combustion engine 2 drives four dog clutches, so as to produce four gearbox ratios, while the electric motor 3 drives two dog clutches, so as to produce two gearbox ratios.

[0023] To manage the operation of these different elements, the vehicle 1 according to the invention preferentially carries a first computer 5 which manages the operation of the gearbox 4, being configured in particular to determine, as a function of a value of the torque of the vehicle requested, an operating strategy of the gearbox 4 which, as will be seen below, establishes directly or indirectly the dog clutch positions of the dog clutches of the gearbox 4 over time.

[0024] A second computer 6 manages the operation of the internal combustion engine 2, being configured in particular to determine a torque setpoint, i.e. a time distribution of torque values, as a function of a value of the torque of the vehicle requested.

[0025] A third computer 7 similarly manages the operation of the electric motor 3, also being configured to determine a torque setpoint based on a value of the required vehicle torque.

[0026] A fourth computer 8 is configured to determine a value of the requested vehicle torque as a function of an action performed on the vehicle's accelerator pedal, which is detected and measured by means of a suitable sensor (not shown), or as a function of an instruction transmitted by a cruise control 9 or a driver assistance system 10 of the vehicle 1.

[0027] Advantageously, the vehicle 1 according to the invention includes a device 100 for managing the operation of a thermal engine of a motor vehicle equipped with a dog clutch gearbox driven by the thermal engine and at least one electric motor within the meaning of the present invention, as described below, which implements a method for managing the operation of a thermal engine of a motor vehicle equipped with a dog clutch gearbox driven by the thermal engine and at least one electric motor within the meaning of the present invention, as briefly summarized below and described in detail further down.

[0028] During the implementation of the method, the device 100 according to the invention determines whether the value of the requested vehicle torque, which is established by the fourth control unit 8 based on an action performed by the driver on the accelerator pedal of the vehicle 1 or an instruction transmitted by the cruise control 9 or the driver assistance system 10, increases beyond a pre-established threshold value. Simultaneously, it determines whether an operating strategy of the gearbox 4, which is established by the first control unit 5, involves the engagement of a dog clutch of the gearbox 4, which is driven by the electric motor 3, and the disengagement of a dog clutch of the gearbox. Speeds 4, which are driven by the internal combustion engine 2. And when these two conditions are met, the device 100 according to the invention then manages the operation of the internal combustion engine 2 according to a constant torque setpoint (i.e., a setpoint for maintaining constant torque), and this continues until the electric motor 3 engages. In other words, the torque value used to manage the operation of the internal combustion engine 2 is momentarily fixed. As will be seen later, this is how the device 100 according to the invention avoids the acceleration lag mentioned in the preamble, and thus contributes to improving the comfort and performance of hybrid vehicles equipped with dog-clutch transmissions.

[0029] The device 100 for managing the operation of a thermal engine of a motor vehicle equipped with a dog clutch gearbox driven by the thermal engine and at least one electric motor according to the invention is illustrated in [Fig.2]. It is essentially a computer device, which includes at least one information processing unit 101, comprising one or more processors, a data storage medium 102, on which is recorded in particular a program which includes program code instructions for the execution of the steps of the process according to the invention described later, and an input and output interface 103 allowing the reception and transmission of data.

[0030] Preferably, the device 100 according to the invention is integrated into an independent computer and interacts via its input / output interface 103 and by means of a wired vehicle communication network (e.g., CAN, Ethernet, MOST, etc.) – represented by the arrows in [Fig. 1] – with the first computer 5, which manages the operation of the gearbox 4, and with the second computer 6, which manages the operation of the internal combustion engine 2. Alternatively, the device 100 according to the invention is partially or fully integrated into the second computer 6. By these means, the device 100 according to the invention can, in particular, determine a current value of the vehicle's torque 1 and can obtain data characterizing a requested vehicle torque value by interacting with the fourth computer 8.It can also manage the operation of the internal combustion engine 2 by interacting either with the second computer 6 or directly with the internal combustion engine 2.

[0031] According to the invention, all the elements described above contribute to enabling the implementation of a method for managing the operation of a thermal engine of a motor vehicle equipped with a dog clutch gearbox driven by the thermal engine and at least one electric motor, as described below in relation to figures 3-5.

[0032] Figure [Fig.3] illustrates by means of a flowchart the steps of the process according to the invention.

[0033] According to a first step 301 of the method according to the invention, the device 100 according to the invention determines whether a first condition is met, said first condition being met when it is established that a value of the torque of the requested vehicle increases beyond a pre-established threshold value.

[0034] In other words, the device 100 according to the invention first determines whether the situation mentioned in the preamble is present, namely that of a sudden and decisive acceleration request while the vehicle is traveling at cruising speed. Such a request for acceleration occurs when the driver fully depresses the accelerator pedal and, similarly, whether the cruise control 9 or the driver assistance system 10 generates an instruction reproducing this situation. Indeed, during acceleration, the required torque necessarily increases. Thus, the device 100 according to the invention advantageously focuses, during this first step 301, on monitoring this situation, which usually results in a hesitation during acceleration.

[0035] To implement this first step, the device 100 according to the invention interacts with the fourth computer 8 to obtain the requested vehicle torque value, which the latter establishes based on an action performed on the accelerator pedal of vehicle 1 or an instruction generated by the cruise control 9 or the driver assistance system 10. Similarly, it obtains the current torque value of vehicle 1 by also interacting with this same computer. Regarding the first threshold value, for example, between 800 Nm and 1500 Nm, it was preferably recorded on the data storage medium 102 of the device 100 according to the invention during the vehicle design phase.

[0036] Next, according to a second step 302 of the method according to the invention, the device 100 according to the invention obtains data characterizing an operating strategy for the gearbox 4, which is established based on the torque value of the requested vehicle. Thus, in this step, the device 100 according to the invention aims to obtain, by interacting with the first computer 5 that manages the operation of the gearbox 4, an operating strategy for the gearbox 4, which the first computer 5 establishes based on the torque value of the requested vehicle, transmitted to it by the fourth computer 8. This operating strategy defines a gear ratio for the gearbox 4 that allows it to meet the torque value of the requested vehicle.Preferably, the operating strategy defines two gear ratios of the gearbox 4, a first gear for the internal combustion engine 2 and a second gear for the electric motor 3. In other words, the operating strategy of the gearbox 4 establishes, in relation to at least one instant subsequent to the current instant, at least one gear ratio of the gearbox 4. As a result, it indirectly establishes the engaged and disengaged positions of the dog clutches of the gearbox. 4-speed gearbox over time.

[0037] Next, according to a third step 303 of the method according to the invention, the device 100 according to the invention determines whether a second condition is met, considering that this is the case when it establishes that said strategy involves the engagement of a dog clutch of said gearbox 4 which is driven by the electric motor 3 and the disengagement of a dog clutch of the gearbox 4 which is driven by the internal combustion engine 2. In other words, the device 100 according to the invention determines at this stage whether the electric motor 3 will subsequently be engaged to meet the required torque value of the vehicle. This is advantageous in that such engagement of the electric motor 3 occurs precisely in the situation that causes the problems mentioned in the preamble.Indeed, when the driver restarts the engine or when a corresponding instruction is generated, the electric motor 3 is at a certain point engaged while the internal combustion engine 2 reaches its maximum operating point, and this is precisely what causes the acceleration lag.

[0038] Finally, according to a fourth step 304 of the process according to the invention, the device 100 according to the invention manages the operation of the heat engine 2 according to data characterizing a constant torque setpoint when it establishes that the first condition and the second condition are met.

[0039] This torque setting is established based on an initial torque value taken into account for managing the operation of the internal combustion engine 3 at the moment the increase in the requested vehicle torque value occurs, in other words, at the moment the driver restarts the engine or a corresponding instruction is generated. This fourth step of the process is advantageously implemented as long as the engagement of the electric motor 3, as provided for by the gearbox operating strategy, has not yet occurred.

[0040] To implement this step, the device 100 according to the invention interacts with the second computer 6, by transmitting to it a command to use the torque setpoint for managing the operation of the internal combustion engine 2. Alternatively, it manages the operation of the internal combustion engine 2 itself according to the constant torque setpoint.

[0041] For greater clarity, a graph is shown in [Fig. 4] illustrating the situation mentioned in the preamble, namely the driver's re-engagement or a corresponding instruction, when it occurs in a hybrid motor vehicle equipped with a dog-clutch gearbox but lacking the device 100 according to the invention. This graph shows the evolution of the torque of the internal combustion engine 2 during the driver's re-engagement. It also shows the initial instant il at which the electric motor 3 is engaged. It is also shown that the internal combustion engine 2 first increases its torque to its maximum operating point to satisfy the torque value requested, then, as soon as the electric motor 3 has engaged, the torque of the internal combustion engine must decrease so that it can be disengaged at time i2.

[0042] Figure 5 shows a graph illustrating the same situation when it occurs in vehicle 1 according to the invention. The graph shows the evolution of the torque of the internal combustion engine 2 during the driver's acceleration, and the first instant i1 at which the electric motor 3 is engaged. The dashed line represents the constant torque setpoint used to manage the operation of the internal combustion engine 2, which prevents it from reaching its maximum operating point before the electric motor 3 engages. As a result, the torque of the internal combustion engine 2 reaches its disengagement threshold more quickly, at instant i3 prior to instant i2, so that it can be disengaged more rapidly, thus reducing acceleration lag.

[0043] Therefore, thanks to the method and device according to the invention described above, a solution is provided for reducing the response time, which results in acceleration lag during a sharp acceleration request, in a hybrid vehicle equipped with a dog-clutch gearbox. In this way, the invention improves the comfort and performance of hybrid vehicles equipped with dog-clutch gearboxes.

Claims

Demands

1. A method for managing the operation of a heat engine (2) of a motor vehicle (1) equipped with a dog clutch gearbox (4) driven by the heat engine (2) and at least one electric motor (3), said method being implemented by a computer device on board the vehicle, characterized in that said method comprises the steps of: i. determining whether a first condition is met, said first condition being met when it is established that a value of the required vehicle torque increases beyond a pre-established threshold value; ii. obtaining data characterizing an operating strategy of said gearbox (4) which is established as a function of said required vehicle torque value; iii.determine whether a second condition is met, said second condition being met when it is established that said strategy involves the engagement of a dog clutch of said gearbox (4) which is driven by said electric motor (3) and the disengagement of a dog clutch of said gearbox (4) which is driven by said internal combustion engine (2); and iv. manage the operation of said internal combustion engine (2) according to data characterizing a constant torque setpoint when it is established that said first condition and said second condition are met.

2. A method according to claim 1, characterized in that step iv) is carried out as long as said dog clutching has not occurred.

3. A method according to any one of the preceding claims, characterized in that said strategy establishes, in relation to at least one instant subsequent to the current instant, a ratio of said gearbox (4).

4. A method according to any one of the preceding claims, characterized in that said torque setpoint is established as a function of an initial torque value taken into account for the management of the operation of said internal combustion engine (2) at the time when the increase in the value of the required vehicle torque occurs.

5. A method according to any one of the preceding claims, characterized in that that the threshold value is between 800 Nm and 1500 Nm.

6. Device (100) for managing the operation of a thermal engine (2) of a motor vehicle (1) equipped with a dog clutch gearbox (4) driven by the thermal engine (2) and at least one electric motor (3), characterized in that said device comprises an information processing unit (101), with one or more processors, and a data storage medium (102), which are configured to implement a method according to any one of the preceding claims.

7. Computer program comprising program code instructions for carrying out the steps of a process according to any one of claims 1 to 5 when said program is executed by at least one processor.

8. A computer-readable medium, characterized in that a program according to claim 7 is stored thereon.

9. Motor vehicle (1), characterized in that said vehicle carries a device (100) according to claim 6.

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