Method for managing regenerative braking of a motor vehicle

Abstract

The invention relates to a method for managing regenerative braking of a vehicle (100), the vehicle comprising: - first (10) and second (30) electric motors, each driving one axle (11, 21); - a heat engine (20); and - a battery (40) configured to cooperate with the electric motors (10, 30); the method being characterised in that it is triggered during a deceleration phase of the vehicle (100) implementing regenerative braking and in that it comprises: - a step of detecting that a charging threshold of the battery (40) has been exceeded; - a step of rotating the engine (20) by the second electric motor (30) so that it runs idle; and - a step of adjusting the speed of the engine (20) to a value that allows the second motor (30) to consume energy from the battery (40) in order to keep its charging level lower than the maximum charge.

Description

[0001] DESCRIPTION

[0002] TITLE: Method for managing regenerative braking of a motor vehicle.

[0003] The invention relates to a method for managing regenerative braking of a motor vehicle. The invention also relates to a device for managing regenerative braking of a motor vehicle and to a motor vehicle comprising such a regenerative braking management device. Finally, the invention also relates to a computer program implementing the mentioned method.

[0004] In the automotive industry, motor vehicles are commonly equipped with driver assistance systems. On vehicles equipped with electric machines coupled to the axles of said vehicles, it is possible to recover energy during vehicle deceleration phases or constant speed descent phases, when these electric machines are in regenerative mode. This regenerative mode, also called "regenerative braking", allows the vehicle battery to be recharged with energy in order to use the electric machine in traction phases at other times of driving.

[0005] To recover as much energy as possible to recharge the battery, it is best to brake the vehicle using the axle connected to the electric powertrain. However, during regenerative operation, the battery may reach its maximum charge state and cannot store any more energy. Regenerative braking is then interrupted, and if the vehicle is still on a downward slope, such as a mountain pass, the vehicle may accelerate due to the downward slope, which can surprise the driver and be dangerous.In other words, when the battery has reached its maximum state of charge due to regenerative braking, the latter is then interrupted, and in this case, the driver of the motor vehicle is obliged to carry out manual intervention on the braking system control to renew his speed setting, in order to control the deceleration and / or maintain a constant speed when descending.

[0006] The aim of the invention is to overcome this drawback. The invention thus relates to a method for managing regenerative braking of a motor vehicle which is simple and reliable, and which avoids the driver having to carry out manual intervention on the braking system control to renew his speed setting.

[0007] To this end, the invention relates to a method for managing regenerative braking of a motor vehicle, the motor vehicle comprising a first electric machine configured to drive a first axle; a heat engine coupled to a second axle; a second electric machine configured to drive the heat engine; a battery configured to cooperate on the one hand with the first electric machine and on the other hand with the second electric machine; a gearbox with controlled clutch and a computer configured to manage and supervise the management of the energy of the motor vehicle;the method being characterized in that it is triggered during a deceleration phase of the vehicle by implementing regenerative braking by the first axle coupled to the first electric machine so as to transform the kinetic energy into electric current in order to allow recharging of the battery, and in that the method comprises a first step of detection by the computer of an exceeding of a predetermined battery charging threshold; a second step of starting rotation of the thermal engine by the second electric machine so that said thermal engine runs at no load, the gearbox with piloted clutch being disengaged, if said predetermined battery charging threshold is exceeded;and a third step of adjusting the speed of the thermal engine to a value allowing the second electric machine to consume the energy from the battery so as to maintain the charge level of the battery below its maximum state of charge, if said predetermined battery charging threshold is exceeded.;

[0008] This process automatically maintains the battery in a state of charge close to maximum and ensures the continuity of regenerative braking throughout the descent without intervention from the driver.

[0009] Optionally, the ECU is configured to maintain regenerative braking within a deceleration interval of + / - 0.2m / s 2 .

[0010] Optionally, the predetermined threshold of battery charging detected by the computer is greater than or equal to 80% of the maximum state of charge of the battery.

[0011] Optionally, the value of the thermal engine speed when adjusting the thermal engine speed allowing the second electric machine to consume battery energy is between 1000 rpm and 3500 rpm.

[0012] Optionally, the first axle to which the first electric machine is coupled is arranged at the rear of the motor vehicle and the second axle to which the thermal engine is coupled is arranged at the front of the motor vehicle.

[0013] Alternatively, the first axle to which the first electric machine is coupled is arranged at the front of the motor vehicle and the second axle to which the heat engine is coupled is arranged at the rear of the motor vehicle. In addition, the method comprises at least one additional step, this step taking place at the same time as the second step and the third step; during this additional step, the vacuum generated within the heat engine which is running idle is used in a brake booster of the motor vehicle.

[0014] Optionally, the method comprises at least one additional step at the end of the method, this step being triggered when the vehicle receives the instruction to accelerate and the at least one additional step comprises a step of stopping the regenerative braking; a step of coupling the gearbox with controlled clutch to the first electric machine so as to generate acceleration of the motor vehicle; and / or a step of coupling the gearbox with controlled clutch to the thermal engine so as to generate acceleration of the motor vehicle.

[0015] The invention also relates to a device for managing regenerative braking of a motor vehicle, the device comprising hardware and / or software elements implementing the method according to the invention, in particular hardware and / or software elements designed to implement the method according to the invention, and / or the device comprising means for implementing the steps of the method according to the invention.

[0016] The invention further relates to a motor vehicle comprising such a regenerative braking management device.

[0017] The invention also relates to a computer program product comprising program code instructions recorded on a computer-readable medium for implementing the steps of the method according to the invention when said program operates on a computer or computer program product downloadable from a communication network and / or recorded on a data medium readable by a computer and / or executable by a computer, characterized in that it comprises instructions which, when the program is executed by the computer, lead the latter to implement the steps of the method according to the invention.

[0018] The invention further relates to a computer-readable data storage medium on which is recorded a computer program comprising program code instructions for implementing the method according to the invention or a computer-readable storage medium comprising instructions which, when executed by a computer, cause the latter to implement the steps of the method according to the invention.

[0019] The invention further relates to a signal of a data carrier, carrying the computer program product according to the invention.

[0020] The attached drawings represent, by way of example, an embodiment of an emergency braking device according to the invention and an embodiment of an emergency braking method according to the invention.

[0021] Figure 1 represents an embodiment of a motor vehicle implementing a method for managing regenerative braking according to the invention.

[0022] Figure 2 is a flowchart of a first mode of execution of a method for managing regenerative braking according to the invention.

[0023] Figure 3 is a flowchart of a second embodiment of a method for managing regenerative braking according to the invention. Figure 4 is a flowchart of a third embodiment of a method for managing regenerative braking according to the invention.

[0024] The motor vehicle 100 according to the embodiment of the invention may be a vehicle of any type, in particular a passenger vehicle, a utility vehicle, a truck or even a public transport vehicle such as a bus or a shuttle.

[0025] An embodiment of a motor vehicle 100 equipped with the invention is described below with reference to FIG. 1. It is more particularly a hybrid motor vehicle which uses two types of engines.

[0026] Thus, the motor vehicle 100 is equipped with a first electric machine 10 configured to drive a first axle 11, a heat engine 20 coupled to a second axle 21 and a second electric machine 30 configured to drive the heat engine 20, as well as a battery 40 configured to cooperate on the one hand with the first electric machine 10 and on the other hand with the second electric machine 30.

[0027] The motor vehicle 100 equipped with the invention therefore comprises two separate electrical machines 10 and 30, preferably one on each axle 11 and 21 of the motor vehicle 100.

[0028] Thus, according to a first preferred embodiment of the invention, the first axle 11 to which the first electric machine 10 is coupled is arranged at the rear of the motor vehicle 100 while the second axle 21 to which the thermal engine 20 is coupled is arranged at the front of the motor vehicle 100. In this first embodiment, the motor vehicle 100 may be equipped with a reducer such as an electric reducer which cooperates with the first electric machine 10 arranged at the rear of the motor vehicle 100. This electric reducer may have various configurations which make it possible to adapt the reduction in force and speeds according to the uses during the driving of the vehicle 100. In particular, a distinction may be made between the conventional use of a motor vehicle on roads built for this purpose (this use is commonly called "on-road" in English) and an all-terrain driving use (commonly called "offroad" in English).

[0029] According to a second preferred embodiment of the invention, the first axle 11 to which the first electric machine 10 is coupled is arranged at the front of the motor vehicle 100 while the second axle 21 to which the thermal engine 20 is coupled is arranged at the rear of the motor vehicle 100.

[0030] Arranging the thermal engine 20 at the rear of the motor vehicle 100 allows for better mass balancing, which contributes to better traction of said vehicle 100.

[0031] Alternatively, the motor vehicle 100 may be equipped with a coupling and decoupling system which makes it possible to couple or decouple the first electric machine 10 between the first axle 11 and the second axle 21.

[0032] Under certain conditions, the first electric machine 10 alone allows the motor vehicle 100 to be towed. During deceleration phases or when the vehicle 100 is traveling at a stabilized speed, this first electric machine 10 also allows regenerative braking to be performed to recover energy in order to recharge the battery 40. The motor vehicle 100 is also equipped with a gearbox 50 with a controlled clutch and a computer 60 configured to manage and supervise the energy management of the motor vehicle 100.

[0033] During the deceleration phases or the constant speed descent phases of the motor vehicle 100, the computer 60 which supervises the energy management of the motor vehicle 100 can control the regenerative braking by the first axle 11 to which the first electric machine 10 is coupled. This regenerative braking then makes it possible to convert the kinetic energy of the vehicle 100 into electric current and thus to recharge the battery 40 of the motor vehicle.

[0034] According to a preferred embodiment, the computer 60 is configured to maintain regenerative braking within a deceleration interval of + / - 0.2 m / s 2 This deceleration interval corresponds to an acceptability criterion which makes it possible to ensure balanced deceleration of the motor vehicle 100, i.e. without sudden changes in speed, which makes it possible to ensure the comfort of the driver and passengers in the motor vehicle 100.

[0035] The method for managing regenerative braking targeted by the invention is triggered in specific situations, in particular when the motor vehicle 100 is traveling on a downward slope. Here, the term "downward slope" means a slope with a percentage greater than or equal to 5%, that is to say that for every hundred meters traveled by the motor vehicle 100 downhill, the difference in level is at least five meters. A common example of downward slopes are in particular mountain passes.

[0036] A first mode of execution for managing regenerative braking is described below with reference to FIG. 2. The method for managing regenerative braking is more particularly triggered when the computer 60 detects that a charging threshold of the battery 40 has been exceeded, which corresponds to the first step E1 of the method. This threshold is close to the maximum state of charge of the battery 40; it corresponds, for example, to 80% of the maximum state of charge of the battery 40.

[0037] When a crossing of this threshold is detected by the computer 60, the second electrical machine 30 sets the heat engine 20 in rotation so that it runs at no load, that is to say that the heat engine 20 runs without injection and there is no combustion. This corresponds to the second step E2 of the method. The gearbox 50 with piloted clutch is then disengaged.

[0038] The battery 40 therefore continues to be powered by the regenerative braking maintained by the first electric machine 10 while the second electric machine 30 consumes energy by running the thermal engine 20 at no load so as to maintain the charge level of the battery 40 below its maximum charge state.

[0039] In order to find a balance between the energy recovered by regenerative braking and the consumption of this energy by the second electric machine 30 which runs the thermal engine 20 at no load, the speed of the thermal engine is adjusted to a value allowing the second electric machine 30 to consume the energy of the battery 40 so as to maintain its charge level below its maximum state of charge, if said predetermined charging threshold of the battery 40 is exceeded. This corresponds to the third step E3 of the method.

[0040] During this third step E3 of the method, the value of the speed of the thermal engine is for example between 1000 revolutions per minute and 3500 revolutions per minute. The value of the engine speed depends on several parameters such as the percentage of the slope, the number and weight of the passengers in the motor vehicle 100, the weight of the load possibly transported by the vehicle 100 or the type of request to which the vehicle 100 must respond, such as instructions concerning the heating or air conditioning of the passenger compartment for example.

[0041] In a second mode of execution for managing regenerative braking, the method for managing regenerative braking may comprise at least one additional step E4, in particular in the case where the vehicle 100 is equipped with a vacuum brake booster 70. Such a second mode of execution for managing regenerative braking is described below with reference to FIG. 3.

[0042] A brake booster 70 (commonly called a “mastervac” in English) generally makes it possible to improve braking efficiency by amplifying the force that the driver applies to the brake pedal. In the case of the method described here, the additional step E4 takes place at the same time as the second step E2 and the third step E3 of the method. During this additional step E4, the vacuum generated within the heat engine 20 which is running at no load is used in a brake booster 70 of the motor vehicle 100. In other words, the pressure difference necessary for the operation of the brake booster 70 is generated by the heat engine 20 which is running at no load. There is therefore no need to provide a specific vacuum pump to create a vacuum at the brake booster 70, since this function is already performed by the heat engine 20.

[0043] In a third mode of execution of management of regenerative braking, the method of management of regenerative braking may comprise at least one other additional step E5, E61, E62. Such a third mode of execution of management of regenerative braking is described below with reference to FIG. 4.

[0044] This step or steps E5, E61, E62 are triggered when the motor vehicle 100 receives the instruction to accelerate, for example when the driver presses the accelerator pedal.

[0045] When the vehicle 100 receives such an acceleration instruction, the computer 60 interrupts the regenerative braking. This corresponds to step E5.

[0046] The computer 60 then gives an order to the gearbox 50 with controlled clutch so that it engages with the first electric machine 10 so as to cause acceleration of the motor vehicle 100. This corresponds to step E61.

[0047] In addition or alternatively, the computer 60 can give an order to the gearbox 50 with controlled clutch so that it engages with the thermal engine 20 so as to cause acceleration of the motor vehicle. This corresponds to step E62.

[0048] The choice of coupling the gearbox 50 with piloted clutch with either the first electric machine 10, or the thermal engine 20, or both, depends on the level of acceleration requested by the driver of the motor vehicle 100.

[0049] Finally, the method for managing regenerative braking according to the invention is simple to implement and only uses technical means already present on current vehicles.

Claims

CLAIMS 1. Method for managing regenerative braking of a motor vehicle (100), the motor vehicle comprising: - a first electric machine (10) configured to drive a first axle (11); - a heat engine (20) coupled to a second axle (21); - a second electric machine (30) configured to drive the heat engine (20); - a battery (40) configured to cooperate on the one hand with the first electric machine (10) and on the other hand with the second electric machine (30); - a gearbox (50) with piloted clutch; - a computer (60) configured to manage and supervise the management of the energy of the motor vehicle (100); the method being characterized in that it is triggered during a deceleration phase of the vehicle (100) by implementing regenerative braking by the first axle (11) coupled to the first electric machine (10) so as to transform the kinetic energy into electric current in order to allow recharging of the battery (40), and in that the method comprises the following steps (E1, E2, E3): - a first step (E1) of detection by the computer (60) of an exceeding of a predetermined charging threshold of the battery (40); - a second step (E2) of rotating the heat engine (20) by the second electric machine (30) so that said heat engine (20) rotates at no load, the gearbox (50) with controlled clutch being disengaged, if said predetermined charging threshold of the battery (40) is exceeded; - a third step (E3) of adjusting the speed of the thermal engine (20) to a value allowing the second electric machine (30) to consume the energy from the battery (40) so as to maintaining the charge level of the battery (40) below its maximum state of charge, if said predetermined charging threshold of the battery (40) is exceeded.

2. Method for managing regenerative braking according to the preceding claim, characterized in that the computer (60) is configured to maintain the regenerative braking within a deceleration interval of + / - 0.2m / s 2 .

3. Method for managing regenerative braking according to one of the preceding claims, characterized in that the predetermined threshold of the charging of the battery (40) detected by the computer (60) is greater than or equal to 80% of the maximum state of charge of the battery (40).

4. Method for managing regenerative braking according to one of the preceding claims, characterized in that the value of the speed of the thermal engine (20) during the adjustment of the speed of the thermal engine (20) allowing the second electric machine (30) to consume the energy of the battery (40) is between 1000 rpm and 3500 rpm.

5. Method for managing regenerative braking according to one of the preceding claims, characterized in that the first axle (11) to which the first electric machine (10) is coupled is arranged at the rear of the motor vehicle (100) and in that the second axle (21) to which the thermal engine (20) is coupled is arranged at the front of the motor vehicle (100).

6. Method for managing regenerative braking according to one of claims 1 to 5, characterized in that the first axle (11) to which the first electric machine (10) is coupled is arranged at the front of the motor vehicle (100) and in that the second axle (21) to which the thermal engine (20) is coupled is arranged at the rear of the motor vehicle (100).

7. Method for managing regenerative braking according to the preceding claim, characterized in that it comprises at least one additional step (E4), this step taking place at the same time as the second step (E2) and the third step (E3), and in that during this additional step (E4), the depression generated within the thermal engine (20) which is running idle is used in a brake booster (70) of the motor vehicle (100).

8. Method for managing regenerative braking according to the preceding claim, characterized in that it comprises at least one additional step (E5, E61, E62) at the end of the method, this step being triggered when the vehicle (100) receives the instruction to accelerate and in that the at least one additional step (E5, E61, E62) comprises: - a step (E5) of stopping regenerative braking; - a step (E61) of coupling the gearbox (50) with controlled clutch to the first electric machine (10) so as to generate acceleration of the motor vehicle (100); and / or - a step (E62) of coupling the gearbox (50) with controlled clutch to the thermal engine (20) so as to generate acceleration of the motor vehicle (100).

9. Device for managing regenerative braking of a motor vehicle, the device comprising hardware and / or software elements implementing the method according to one of the preceding claims, in particular hardware and / or software elements designed to implement the method according to one of the preceding claims, and / or the device comprising means for implementing the method according to one of the preceding claims.

10. Motor vehicle (100) comprising a regenerative braking management device according to the preceding claim.

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