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 hybrid motor vehicle (1) equipped with a dog-clutch gearbox (4) driven by 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 of a hybrid motor vehicle equipped with a dog gearbox Technical field of the invention

[0001] The present invention relates to the field of computer and electronic systems on board motor vehicles for managing their operation. The invention relates in particular to a method for managing the operation of a thermal engine of a hybrid motor vehicle equipped with a dog gearbox driven by at least one electric motor which is implemented by a computer device on board the vehicle. The invention also relates to a device implementing such a method, as well as a motor vehicle which has such a device on board. The invention applies to motor vehicles such as land motor vehicles, in particular cars. State of the prior art

[0002] Certain hybrid motor vehicles (i.e. with a hybrid thermal and electric engine) are equipped with a dog gearbox which is driven jointly by a thermal engine and at least one electric motor, one or more dogs of the gearbox thus being driven by the thermal engine while one or more others are driven by the electric motor. In such a vehicle, an action carried out by the driver on the accelerator pedal of the vehicle is therefore interpreted by the vehicle's computers in order to manage the operation of the gearbox, in particular according to an operating strategy which establishes a gearbox ratio according to a value of the requested torque of the vehicle, and that of the engines, in particular according to torque setpoints which are determined.

[0003] For example, in a situation in which the driver releases his foot, i.e. he removes all or part of the pressure he exerts with his foot on the accelerator pedal, while the vehicle is traveling at a cruising speed of the order of 100 km / h, a computer for managing the operation of the gearbox generally establishes an operating strategy which causes the dog clutch driven by the electric motor to engage while a dog clutch of the gearbox remains driven by the thermal engine. At the same time, a computer for managing the operation of the thermal engine establishes a torque reduction instruction.

[0004] However, due to the effects inherent in the air chain, the heat engine executes the torque reduction instruction after a certain incompressible delay. And during this period of time during which the thermal engine has not yet reduced its torque, a dog clutch driven by the electric motor is engaged, and, as a result, the thermal engine operation management computer establishes an inverse torque increase instruction to minimize the vehicle's fuel consumption. These two opposing instructions lead to consecutive changes in the torque of the thermal engine and that of the electric motor, which, at a certain moment, generate a shock that creates discomfort for the vehicle's occupants.

[0005] This inconvenience also occurs in a situation in which the driver presses lightly on the accelerator pedal while the vehicle is traveling at cruising speed, causing, in addition to a shock, excess fuel consumption.

[0006] And obviously, these same inconveniences occur in the same way if it is a cruise control or any other computer of a driving assistance system which generates a command or an instruction which reproduces these situations. Summary of the invention

[0007] The invention aims to overcome these drawbacks. In particular, it aims to provide a solution for, in a hybrid vehicle equipped with a dog gearbox, preventing a shock from occurring in the situations described above. By this means, the invention aims to improve the comfort of hybrid motor vehicles equipped with dog gearboxes while minimizing their fuel consumption.

[0008] In order to achieve these objectives, the invention relates, according to a first aspect, to a method for managing the operation of a thermal engine of a hybrid motor vehicle equipped with a dog gearbox driven by at least one electric motor, said method being implemented by a computer device on board the vehicle, the method comprising the steps of: i. determining whether a first condition is met, said first condition being met when it is established at least that a value of the torque of the requested vehicle falls below a first pre-established threshold value or exceeds a current value of the torque of the vehicle by a value less than a second pre-established threshold value; ii. obtain data characterizing an operating strategy of said gearbox which is established as a function of said value of the requested vehicle torque; iii. determining whether a second condition is met, said second condition being met when it is established that said strategy involves the dog clutching of a dog clutch of said gearbox which is driven by said engine electric; and iv. manage the operation of said heat engine based on data characterizing a constant torque setpoint when it is established that said first condition and said second condition are met.

[0009] According to a variant, step iv) can be carried out as long as said dog clutch has not occurred.

[0010] According to another variant, said strategy can establish, in connection with at least one instant subsequent to the current instant, a gearbox ratio.

[0011] According to yet another variant, said torque setpoint can be established as a function of an initial torque value taken into account for managing the operation of said thermal engine at the moment when a variation in the value of the torque of the requested vehicle occurs.

[0012] According to yet another variant, said first threshold value may be equal to 1500 Nm.

[0013] According to yet another variant, said second threshold value may be between 1 Nm and 300 Nm.

[0014] According to yet another variant, said first condition can be fulfilled when it is also established that at least one battery of the vehicle is capable of accepting energy generated by said electric motor.

[0015] According to yet another variant, said first condition can be fulfilled when it is also established that the value of the requested vehicle torque is not achievable taking into account the gear ratio(s) of the gearbox which is / are engaged at the current time.

[0016] According to a second aspect, the invention relates to a device for managing the operation of a thermal engine of a hybrid motor vehicle equipped with a dog gearbox driven by at least one electric motor, the device comprising at least one information processing unit, comprising at least one processor, and a data storage medium, which are configured to implement a method as described above.

[0017] According to a third aspect, the invention relates to a computer program comprising program code instructions for executing the steps of a method as described above when said program is executed by at least one processor.

[0018] According to a fourth aspect, the invention relates to a medium usable in a computer on which a program as described above is recorded.

[0019] According to a fifth aspect, the invention relates to a motor vehicle which has a device as described above. Brief description of the figures

[0020] Other characteristics and advantages of the invention will appear on examining the detailed description below, and the appended figures, in which:

[0021] [Fig-1] is a schematic illustration of a motor vehicle according to the invention;

[0022] [Fig.2] is a functional diagram of a device according to the invention;

[0023] [Fig.3] is a flowchart of the steps of a method according to the invention;

[0024] [Fig.4] illustrates the operation of a motor vehicle according to the prior art; and

[0025] [Fig.5] illustrates the implementation of at least one step of the method according to the invention. Detailed description of the invention

[0026] [Fig.l] schematically illustrates a motor vehicle 1 according to the invention. It is a hybrid vehicle comprising a heat engine 2 and at least one electric motor 3 which jointly drive a dog gearbox 4. Thus, some dogs of the gearbox 4 are driven by the heat engine 2, while other dogs are driven by the electric motor 3. According to a preferred embodiment, the heat engine 2 drives four dogs, so as to produce four gearbox ratios, while the electric motor 3 drives two dogs, so as to produce two gearbox ratios.

[0027] To manage the operation of these different elements, the vehicle 1 according to the invention preferably incorporates 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 requested vehicle, an operating strategy of the gearbox 4 which, as will be seen below, indirectly establishes the clutched or disengaged positions of the clutches of the gearbox 4 at a later time.

[0028] A second computer 6 manages the operation of the thermal engine 2, in particular being configured to determine a torque setpoint, i.e. a temporal distribution of torque values, as a function of a value of the requested vehicle torque.

[0029] A third computer 7 similarly manages the operation of the electric motor 3, also being configured to determine a torque setpoint as a function of a value of the requested vehicle torque.

[0030] A fourth computer 8 is configured to determine a value of the requested vehicle torque as a function of an action performed on the accelerator pedal of the vehicle, an action which is detected and measured by means of an appropriate sensor (not shown), or as a function of an instruction transmitted by a cruise control 9 or a driving assistance system 10 of the vehicle 1.

[0031] The vehicle 1 according to the invention advantageously carries a device 100 of management of the operation of a thermal engine of a hybrid motor vehicle equipped with a dog gearbox driven by at least one electric motor within the meaning of the present invention, as described below, which implements a method of managing the operation of a thermal engine of a hybrid motor vehicle equipped with a dog gearbox driven by at least one electric motor within the meaning of the present invention, as described below.

[0032] When implementing the method, the device 100 according to the invention determines whether the value of the requested vehicle torque, which is established by the fourth computer 8 as a function of an action performed by the driver on the accelerator pedal of the vehicle 1 or of an instruction transmitted by the cruise control 9 or the driving assistance system 10, is lower than a pre-established threshold value or higher than a current value of the vehicle torque by a value lower than a second pre-established threshold value. At the same time, it determines whether an operating strategy of the gearbox 4 which is established by the first computer 5 involves the dog clutching of a dog clutch driven by the electric motor 3.And when these two conditions are met, the device 100 according to the invention then manages the operation of the thermal engine 2 according to a constant torque setpoint, and this, as long as the dog clutch of the electric motor 3 has not occurred. In other words, the torque value taken into account for the management of the operation of the thermal engine 2 is momentarily frozen. As will be seen below, it is in this way that the device 100 according to the invention avoids the inconveniences mentioned in the preamble, and that it thus contributes to an improvement in the comfort of hybrid motor vehicles equipped with dog clutch gearboxes while minimizing their fuel consumption.

[0033] The device 100 for managing the operation of a thermal engine of a hybrid motor vehicle equipped with a dog gearbox driven by at least one electric motor according to the invention is illustrated in [Fig.2]. It is essentially a computer device, which comprises 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 comprises program code instructions for the execution of the steps of the method according to the invention described later, and an input and output interface 103 allowing the reception and transmission of data.

[0034] Preferably, the device 100 according to the invention is integrated into an independent computer and it interacts via its input and output interface 103 and by means of a wired communication network of the vehicle (e.g. CAN, Ethernet, MOST, etc.) - shown by the arrows in [Fig.l] - with the first computer 5, the one which manages the operation of the gearbox 4, and with the second computer 6, the one which manages the operation of the thermal engine 2. Alternatively, the device 100 according to the invention is partially or fully part of the second computer 6. Thanks to these means, the device 100 according to the invention can therefore, in particular, determine a current value of the torque of the vehicle 1 and it can obtain data characterizing a value of the torque of the requested vehicle by interacting with the fourth computer 8. It can also manage the operation of the thermal engine 2 by interacting either with the second computer 6 or directly with the thermal engine 2.

[0035] According to the invention, all the elements described above combine to enable the implementation of a method for managing the operation of a thermal engine of a hybrid motor vehicle equipped with a dog gearbox driven by at least one electric motor, as described below in connection with Figures 3-5.

[0036] [Fig. 3] illustrates by means of a flowchart the steps of the method according to the invention.

[0037] 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, considering that such is the case when it establishes at least that a value of the torque of the requested vehicle falls below a first pre-established threshold value or exceeds a current value of the torque of the vehicle by a value lower than a second pre-established threshold value.

[0038] In other words, the device 100 according to the invention first determines whether one is in one of the situations mentioned in the preamble, namely that of releasing the foot or that in which the driver lightly presses the accelerator pedal while the vehicle is traveling at cruising speed. In the same way, it therefore determines whether one is in a case where it is the cruise control 9 or the driving assistance system 10 which generates an instruction reproducing one or other of these situations. Indeed, when releasing the foot or when a corresponding instruction is generated, the requested torque necessarily drops. On the contrary, in the second situation or when a corresponding instruction is generated, a slight increase in the requested torque is inevitably observed.Thus, the device 100 according to the invention advantageously focuses during this first step 301 on monitoring these situations likely to generate discomfort or overconsumption.

[0039] To implement this first step, the device 100 according to the invention interacts with the fourth computer 8 in order to obtain the value of the torque of the requested vehicle that the latter establishes as a function of an action carried out on the accelerator pedal of the vehicle 1 or of an instruction generated by the regulator 9 or the driving assistance system 10. Similarly, it obtains the current value of the torque of the vehicle 1 by also interacting with this same computer. Concerning the first threshold value, for example equal to 1500 Nm, and the second threshold value, for example between 1 Nm and 300 Nm, they were preferably recorded on the data storage medium 102 of the device 100 according to the invention at the time of design of the vehicle.

[0040] According to an alternative, the device 100 according to the invention considers that the first condition is fulfilled when it also establishes that at least one battery of the vehicle 1 is capable of accepting energy generated by the electric motor 3. Here, the capacity of the vehicle battery to absorb a surplus charge which is potentially generated during the implementation of the method according to the invention is ensured.

[0041] According to another alternative, the device 100 according to the invention considers that the first condition is fulfilled when it also establishes that the value of the requested vehicle torque is not achievable taking into account the ratio(s) of the gearbox 4 which is (are) engaged at the current time.

[0042] Then, 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 of the gearbox 4 which is established as a function of the value of the torque of the requested vehicle. Thus, the device 100 according to the invention seeks during this step to obtain, by interacting for this purpose with the first computer 5 which manages the operation of the gearbox 4, an operating strategy of the gearbox 4, which the first computer 5 establishes as a function of the value of the torque of the requested vehicle which is transmitted to it by the fourth computer 8. This operating strategy defines a ratio of the gearbox 4 which makes it possible to satisfy the value of the torque of the requested vehicle.Preferably, the operating strategy defines two ratios of the gearbox 4, a first ratio for the thermal engine 2 and a second ratio for the electric motor 3. In other words, the operating strategy of the gearbox 4 establishes, in connection with at least one instant subsequent to the current instant, at least one ratio of the gearbox 4.

[0043] Then, 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 the operating strategy of the gearbox 4 obtained during the previous step involves the dog clutching of a dog clutch which is driven by the electric motor 3. In other words, the device 100 according to the invention determines at this stage whether the electric motor 3 will subsequently be dog clutched to satisfy the value of the torque of the requested vehicle. This is advantageous in the sense that such dog clutching of the electric motor 3 occurs precisely in the two situations causing inconvenience mentioned in the preamble.In fact, when the foot is released or when a corresponding instruction is generated, the electric motor 3 is at a certain moment engaged and it is precisely this which generates the shock due to the delay imposed by the air chain of the thermal engine 2. Such engagement. of the electric motor 3 also intervenes when the driver lightly presses the accelerator pedal while the vehicle 1 is traveling at cruising speed or when a corresponding instruction is generated by the cruise control 9 or the driving assistance system 10.

[0044] Finally, according to a fourth step 304 of the method according to the invention, the device 100 according to the invention manages the operation of the thermal engine 2 as a function of data characterizing a constant torque setpoint when it establishes that the first condition and the second condition are fulfilled.

[0045] This torque setpoint is established as a function of an initial torque value taken into account for the management of the operation of the thermal engine 3 at the moment when a variation in the value of the torque of the requested vehicle occurs, in other words at the moment of releasing the foot, of slight acceleration or of the generation of a corresponding instruction. This fourth step of the method is implemented as long as the dog clutching of the electric motor 3 provided for by the operating strategy of the gearbox has not occurred.

[0046] 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 heat engine 2. Alternatively, it manages by itself the operation of the heat engine 2 as a function of the constant torque setpoint.

[0047] For greater clarity, [Fig. 4] shows graphs which illustrate the first situation mentioned in the preamble, that of releasing the foot, when it occurs on board a hybrid motor vehicle equipped with a dog gearbox but lacking the device 100 according to the invention.

[0048] A first graph, at the top, illustrates the evolution of the requested vehicle torque in solid lines and the actual evolution of the vehicle torque in dotted lines. A second graph below illustrates, in its upper part, a torque setpoint for managing the operation of the thermal engine 2 in dotted lines and the actual torque of the latter in solid lines, and, in its lower part, a torque setpoint for managing the operation of the electric motor 3.

[0049] These graphs show the variation in the vehicle torque that occurs as a result of the driver releasing his foot and the torque setpoints for each of the motors that are established in correspondence by the second 6 and the third calculator 7. We also see the instant i at which the electric motor 3 is engaged, then disengaged at the moment when the impact occurs. The first threshold value th described above is also mentioned on the top graph.

[0050] We see that, in this situation, the operating strategy of the gearbox 4 established by the first computer 5 specifies the dog clutch of the engine thermal motor 2 together with that of the electric motor 3, the latter via a dog clutch which was until then in neutral position. During the dog clutch phase of the electric motor 3, the thermal engine 2 reduces its torque to satisfy the requested torque value. But, due to the air chain, the torque actually drops after a certain delay. When the electric motor 3 is dog clutched, the second computer 6 commands the return of the torque of the thermal engine 2 to the initial level. Consecutive modifications of the torque of the thermal engine 2 and the electric motor 3 occur, which lead to the generation of the shock.

[0051] In [Fig. 5] are represented in a similar manner graphs which illustrate the same situation when it occurs on board the vehicle 1 according to the invention. A first graph at the top is identical to that illustrated in [Fig. 4]. Nothing changes. On the other hand, the torque setpoint for managing the operation of the thermal engine 2 illustrated in the bottom graph is here constant, equal to the initial torque value taken into account for managing the operation of the thermal engine 2 before (i.e. at the moment when) the driver releases his foot. Indeed, the device 100 according to the invention has first established that the value of the requested vehicle torque falls below the first threshold value th. At the same time, it has determined that the operating strategy of the gearbox 4 involves the dog clutching of the electric motor 3.These two conditions being met, the device 100 according to the invention has therefore generated data characterizing the constant torque setpoint, which is taken into account to manage the operation of the thermal engine 2.

[0052] Thus, no delay effect due to the air chain of the thermal engine 2 occurs since no variation in its torque is required, and this, while an identical reduction in the actual torque of the vehicle occurs (dotted line on the top graph identical to that of [Fig.4]). In fact, no shock due to consecutive modifications of the torque of the thermal engine 2 and the electric motor 3 is generated.

[0053] Consequently, thanks to the method and the device according to the invention described above, a solution is provided for, in a hybrid vehicle equipped with a dog gearbox, preventing a shock from occurring in the situations described in the preamble. By this means, the invention improves the comfort of hybrid motor vehicles equipped with dog gearboxes while minimizing their fuel consumption.

Claims

Claims

1. Method for managing the operation of a thermal engine (2) of a hybrid motor vehicle (1) equipped with a dog gearbox (4) driven by at least one electric motor (3), said method being implemented by a computer device (100) 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 at least that a value of the torque of the requested vehicle falls below a first pre-established threshold value or exceeds a current value of the torque of the vehicle by a value lower than a second pre-established threshold value; ii. obtaining data characterizing an operating strategy of said gearbox which is established as a function of said value of the torque of the requested vehicle; iii.determining whether a second condition is met, said second condition being met when it is established that said strategy involves the clutch engagement of a clutch of said gearbox (4) which is driven by said electric motor (3); and iv. managing the operation of said thermal 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. Method according to claim 1, characterized in that step iv) is carried out as long as said clutching has not occurred.

3. Method according to one of the preceding claims, characterized in that said strategy establishes, in connection with an instant subsequent to the current instant, a ratio of said gearbox (4).

4. Method according to 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 thermal engine (2) at the moment when a variation in the value of the torque of the requested vehicle occurs.

5. Method according to one of the preceding claims, characterized in that that said first threshold value is equal to 1500 Nm.

6. Method according to one of the preceding claims, characterized in that said second threshold value is between 1 Nm and 300 Nm.

7. Method according to one of the preceding claims, characterized in that said first condition is fulfilled when it is also established that at least one battery of the vehicle is capable of accepting energy generated by said electric motor.

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

9. A computer program comprising program code instructions for executing the steps of a method according to any one of claims 1 to 7 when said program is executed by at least one processor.

10. Computer-readable medium, characterized in that a program according to claim 9 is recorded therein.

11. Motor vehicle (1), characterized in that said vehicle carries a device (100) according to claim 8.