Method for managing a deceleration phase of a hybrid type motor vehicle

Abstract

The invention relates to a management method for managing a deceleration phase of a motor vehicle (10'), said motor vehicle comprising a powertrain (10) comprising an electric engine (12) and a thermal engine (11), said method comprising, during a deceleration phase: - an application step for applying a first resistance torque, said first resistance torque corresponding to a negative torque of the electric engine (12) operating in generator mode to charge the battery (24), then - an application step for applying a second resistance torque (Cr_mth) by regulating the engine interconnection clutch (16), said second resistance torque corresponding to a negative torque of the thermal engine (11), - the second resistance torque is applied as soon as a braking torque is reached, said braking torque being equal to the sum of the torque previously applied by the electric engine (12) when reaching the maximum charging capacity of the battery (24) and the mechanical loss torque of the thermal engine (11).

Description

Technical Field

[0001] This invention claims priority to French Application No. 2000798, filed on January 28, 2020, the contents of which (text, drawings and claims) are incorporated herein by reference.

[0002] This invention relates to a management method for managing the deceleration phase of a hybrid type motor vehicle. A "hybrid" type motor vehicle refers to a vehicle that has both a thermal power source and an electrical power source to ensure its own traction. Background Technology

[0003] It is known that a motor vehicle drivetrain may include a traction machine, particularly an electric motor, mounted on the rear axle of the motor vehicle and associated with a reduction gear and with coupling and decoupling devices for coupling and decoupling the electric traction motor from the rear axle.

[0004] It is known that a motor vehicle drivetrain may include a thermal engine and a traction electric motor, the thermal engine and the traction electric motor being mounted on the wheels and axles of the motor vehicle.

[0005] The traction electric motor is connected to the input shaft of the gearbox. The output shaft of the gearbox is connected to the wheels via a differential. The gearbox is, for example, an automatic gearbox, especially a gearbox with a planetary gear system.

[0006] A clutch, referred to as an engine interconnect clutch, is positioned between the thermal engine and the traction electric motor. In the disengaged state, when the electric motor ensures traction for the vehicle in electric driving mode, the engine interconnect clutch isolates the traction electric motor from the thermal engine. The engine interconnect clutch is engaged in thermal driving mode.

[0007] like Figure 1 As shown, during the deceleration phase of the vehicle, particularly during the relaxation of the accelerator pedal, the computer, starting from time t1, controls the application of a resistance torque Cr_mel, which corresponds to the negative torque of the electric motor. The electric motor then operates in generator mode to charge the battery. The braking torque, following the desired braking torque, then corresponds to the resistance torque Cr_mel.

[0008] At time t2, when the maximum charging capacity of the battery is reached, the computer control implements starting the thermal engine and coupling of the latter to the gearbox by at least partially closing the engine interconnection clutch (signal S_mth related to the control of the thermal engine switches to 1). The computer control of the engine interconnection clutch is such that the thermal engine provides a negative torque which makes it possible to obtain the desired braking torque.

[0009] Thus, between times t2 and t3, the electric engine no longer participates in the braking of the motor vehicle and the computer control implements the application of a resistance torque Cr_mth by the thermal engine to follow the desired braking torque Cfs.

[0010] At time t3, the thermal engine is decoupled from the gearbox and then stopped (signal S_mth switches back to 0) so that the vehicle can be switched back into electric running mode.

[0011] The drawback of this method is that the thermal engine is solicited too early, which leads to excessive consumption of fuel and emission of polluting particles. précoce) les moteurs thermiques, ce qui entraîne un gaspillage de carburant et une émission de particules polluantes. SUMMARY

[0012] The invention aims to overcome this drawback effectively by providing a management method for managing a deceleration phase of a motor vehicle comprising a powertrain comprising:

[0013] - an electric engine mechanically coupled to an input shaft of a gearbox,

[0014] - a battery electrically coupled to the electric engine,

[0015] - a thermal engine, and

[0016] - an engine interconnection clutch interposed between the thermal engine and the electric engine,

[0017] - the method comprises, during a deceleration phase:

[0018] - an application step for applying a first resistance torque corresponding to a negative torque of the electric engine operating in generator mode for charging the battery, and

[0019] - an application step for applying a second resistance torque corresponding to a negative torque of the thermal engine, by coupling of the thermal engine to the gearbox by at least partially closing the engine interconnection clutch and starting,

[0020] - once the braking torque is reached, the second resisting torque is applied, the braking torque being equal to the sum of the torque previously applied by the electric engine when reaching the maximum charging capacity of the battery and the mechanical loss torque of the thermal engine.

[0021] Thus, by taking into account the mechanical losses of the thermal engine, the application makes it possible to delay the application of the second resisting torque by the thermal engine. By delaying the application of the negative torque by the thermal engine, the application thus limits the fuel consumption and the carbon dioxide emissions of the vehicle.

[0022] According to an embodiment of the application, the management method comprises a regulation step for regulating the engine interconnection clutch so as to cause the thermal engine to provide a negative torque, the negative torque making it possible to obtain the desired braking torque.

[0023] According to an embodiment of the application, the mechanical loss torque of the thermal engine takes into account the mechanical losses due to friction, the mechanical losses due to pumping, and the mechanical losses related to the driving of auxiliary members such as air conditioners or alternators.

[0024] According to an embodiment of the application, the mechanical loss torque of the thermal engine depends on the target rotational speed of the thermal engine.

[0025] According to an embodiment of the application, the mechanical loss torque is determined by means of a map, the map receiving as input the target rotational speed of the thermal engine and providing as output the associated mechanical loss torque.

[0026] According to an embodiment of the application, the deceleration phase is implemented during a relaxation of the accelerator pedal.

[0027] The application also aims at a computer comprising a memory for storing software instructions for implementing a management method for managing a deceleration phase of a motor vehicle as described above.

[0028] The application additionally relates to a motor vehicle comprising a computer complying with the above. BRIEF DESCRIPTION OF DRAWINGS

[0029] Other objects, characteristics and advantages of the application will become apparent on reading the following non-limiting description and on referring to the appended drawings, in which:

[0030] - Figure 1 , already described, is a graph of the evolution over time of the braking torque of the motor vehicle and of the starting and coupling phases of the transmission of the thermal engine applying a resisting torque when implementing a known management method of the deceleration phase of the motor vehicle;

[0031] - Figure 2 the schematic diagram of a driveline for a motor vehicle, for implementing a management method for managing a deceleration phase of a motor vehicle according to the invention;

[0032] - Figure 3 the graph represents, as a function of time, the evolution of the braking torque of a motor vehicle and of the coupling and starting phase of a hot engine for applying a resistance torque when implementing a management method for managing a deceleration phase of a motor vehicle according to the invention. DETAILED DESCRIPTION

[0033] Figure 2 A driveline 10 for a motor vehicle 10' is shown, comprising a hot engine 11 and a traction electric engine 12, said hot engine and said traction electric engine being fitted on a wheel axle 13 of the motor vehicle 10', in particular a front wheel axle. The hot engine 11 is for example a four-cylinder hot engine. In variants, the hot engine 11 can of course comprise a different number of cylinders, in particular three cylinders or more than four cylinders.

[0034] The traction electric engine 12 is connected to the input shaft of a gearbox 15. The output shaft of the gearbox 15 is connected to the wheels by means of a differential (not shown). The gearbox 15 is for example an automatic gearbox, in particular a gearbox with a planetary gear train.

[0035] A clutch 16, called engine interconnection clutch, is interposed between the hot engine 11 and the traction electric engine 12. The engine interconnection clutch 16 is a regulated clutch, that is to say that its closure and opening and sliding intermediate positions can be controlled automatically by a computer 26, without particular action from the driver. The computer 26 will be described in more detail below.

[0036] In the open state, when the electric engine 12 ensures the traction of the vehicle in electric driving mode, the engine interconnection clutch 16 enables the traction electric engine 12 to be isolated with respect to the hot engine 11. The engine interconnection clutch 16 is closed in the thermic driving mode.

[0037] A second traction electric engine 18 is fitted on the rear wheel axle 19 of the motor vehicle 10' by means of a reduction 22 and by means of coupling and decoupling means 23 for coupling and decoupling the traction electric engine 18 to the rear axle 19.

[0038] The reduction 22 enables very high rotational speeds of the traction electric engine 12 to be compatible with less high rotational speeds of the wheels of the vehicle.

[0039] The coupling and decoupling device 23 can adopt a disengaged state, in which the traction electric engine 18 is decoupled with respect to the rear wheel axle 19, and an engaged state, in which the traction electric engine 18 is coupled with the rear wheel axle 19. The coupling and decoupling device 23 is preferably a dog clutch device. In a variant, the coupling and decoupling device 23 adopts the form of a clutch.

[0040] The battery 24 is here common to the two electric traction engines 12, 18. In a variant, a battery 24 is used, which is associated with each electric traction engine 12, 18.

[0041] The battery 24 is electrically coupled to the traction electric engine 12 and to the traction electric engine 18. The battery 24 is here common to the two traction electric engines 12, 18. In a variant, a battery 24 is used, which is associated with each of the traction electric engines 12, 18.

[0042] The first traction electric engine 12 and the second traction electric engine 18 can have a high operating voltage, in particular a voltage higher than 48 volts.

[0043] The traction electric engines 12, 18 are adapted to convert the electrical energy from the battery 24 into mechanical energy to ensure traction of the vehicle. The electric traction engines 12, 18 are also adapted to operate in generator mode, in which at least one electric engine 12, 18 converts mechanical energy into electrical energy, which can charge the battery 24, in particular during a regenerative braking phase. The traction electric engines 12, 18 then exert a negative torque to the wheels of the vehicle.

[0044] Such an architecture makes it possible for the vehicle to operate in a pure thermal mode, a hybrid propulsion mode, a pure electric propulsion mode, a 4x4 hybrid mode and a 4x4 electric mode.

[0045] The computer 26 ensures the regulation of the different components of the transmission train 10. This computer 26 comprises a memory for storing software instructions for implementing the management method according to the application for managing a deceleration phase of a motor vehicle 10'. The deceleration phase is advantageously implemented during a relaxation of the accelerator pedal.

[0046] As Figure 3 is shown, during the deceleration phase, the computer 26, from the instant tl, controls the implementation of a first resistance torque Cr mel, which corresponds to a negative torque of the traction electric engine 12, which then operates in generator mode to charge the battery 24. The braking torque, which follows the desired braking torque Cfs, then corresponds to the resistance torque Cr mel. The motor vehicle then operates in a regenerative braking phase.

[0047] At time t2, the maximum charge capacity of the battery 24 is reached. Contrary to the method according to the prior art, the resistance torque Cr_mth is not applied from this time but is applied in a delayed manner at time t3.

[0048] More precisely, once the braking torque is reached, the resistance torque Cr_mth of the thermal engine is applied (for the resistance) at time t3, said braking torque being equal to the sum of the torque Crech applied by the electric engine 12 previously at the time of reaching the maximum charge capacity of the battery 24 and of the mechanical loss torque Cpm of the thermal engine 11.

[0049] The mechanical loss torque Cpm takes into account the mechanical losses due to the friction, the mechanical losses due to the pumping, and the mechanical losses related to the driving of auxiliary members such as air conditioners or alternators.

[0050] The mechanical loss torque Cpm depends on the target speed of the thermal engine. Advantageously, the mechanical loss torque Cpm is determined by means of a map receiving as input the target speed of the thermal engine 11 and providing as output the associated mechanical loss torque Cpm.

[0051] At time t3, the computer 26 then regulates the implementation of the start of the thermal engine 11 and the coupling of this thermal engine with the gearbox 15 by at least partial closure of the engine interconnection clutch 16 (signal S_mth related to the control of the thermal engine 11 is switched to 1). The computer 26 regulates the engine interconnection clutch 16 so as to cause the thermal engine 11 to provide a negative torque which makes it possible to obtain the desired braking torque Cfs.

[0052] Thus, between times t3 and t4, the electric engine 12 no longer participates in the braking of the motor vehicle (the resistance torque Cr_mel is no longer applied), and the computer 26 controls the implementation of the application of the resistance torque Cr_mth by the thermal engine 11 from the time at which the braking torque Crech of the thermal engine 11 augmented with the mechanical loss torque Cpm has been reached.

[0053] At time t4, by regulating the implementation of the opening of the clutch 16, the thermal engine 11 is decoupled from the gearbox 15 and then stopped (signal S_mth is switched back to 0). The motor vehicle 10' is then switched back to being in the electric running mode.

[0054] In a variant, the electric engine 18 can also participate in the implementation of the management method according to the application for managing the deceleration phase of the motor vehicle 10'.

[0055] In a variant, the architecture of the powertrain 10 can be reversed, that is to say the traction electric engine 12 and the thermal engine 11 can be fitted on the rear axle 19 of the motor vehicle 10', while the traction electric engine 18, the reduction gear 22 and the coupling and decoupling device 23 can be fitted on the front wheel axle 13 of the motor vehicle 10'.

Claims

1. A management method for managing a deceleration phase of a motor vehicle (10'), said motor vehicle comprising a powertrain (10) comprising: - an electric engine (12) mechanically coupled to an input shaft of a gearbox (15), - a battery (24) electrically coupled to said electric engine (12), - a thermal engine (11), and - an engine interconnection clutch (16) interposed between said thermal engine (11) and said electric engine (12), - when a deceleration phase is implemented, in which said thermal engine (11) is at standstill and said engine interconnection clutch (16) is open, said method comprising: - an application step for applying a first resisting torque (Cr_mel) corresponding to a negative torque of said electric engine (12) operating in generator mode, said generator mode being used to charge said battery (24), and - an application step for applying a second resisting torque (Cr_mth) corresponding to a negative torque of said thermal engine (11), by implementing a coupling and a start of said thermal engine (11) with said gearbox (15) by at least partially closing said engine interconnection clutch (16), characterized in that said second resisting torque (Cr_mth) is applied as soon as a braking torque is reached, said braking torque being equal to the sum of a torque (Crech) previously applied by said electric engine (12) at the moment when a maximum charging capacity of said battery (24) is reached and a mechanical loss torque (Cpm) of said thermal engine (11).

2. The management method according to claim 1, characterized in that, Said management method comprises a regulation step for regulating said engine interconnection clutch (16) so as to cause said thermal engine (11) to provide a negative torque enabling the desired braking torque to be obtained.

3. The management method according to claim 1 or 2, characterized by, The mechanical loss torque (Cpm) of said thermal engine (11) takes into account mechanical losses due to friction, mechanical losses due to pumping and mechanical losses related to the driving of auxiliary members.

4. The management method according to any one of claims 1 to 3, characterized in that, The mechanical loss torque (Cpm) of said thermal engine (11) depends on a target rotational speed of said thermal engine.

5. The management method according to any one of claims 1 to 4, characterized in that, Said mechanical loss torque (Cpm) is determined by means of a map receiving as input a target rotational speed of said thermal engine and providing as output an associated mechanical loss torque (Cpm).

6. The management method according to any one of claims 1 to 5, characterized by, Said deceleration phase is implemented during a relaxation of an accelerator pedal.

7. The management method according to claim 3, characterized by, Said auxiliary members are an air conditioner or an alternator.

8. A computer (26) comprising a memory for storing software instructions for implementing a management method for managing a deceleration phase of a motor vehicle (10') according to any one of claims 1 to 6.

9. A motor vehicle comprising a computer (26) according to claim 8.

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