FR2809352A1 - Drive unit for a hybrid vehicle, has arrangement which ensures smooth torque during the changeover from series to parallel mode and vice-versa - Google Patents

Abstract

The drive unit includes an IC engine (1) connected to a first electric motor-generator (2) associated with a first controllable clutch-sleeve (4) for transmitting the power to the wheels (10) in a hybrid parallel mode, and a second electric motor (3) for transmitting the power to the wheels in a hybrid series mode. A battery feeds the two motors, and an engine management unit (8) receives information of the conditions of these motors, and delivers the torque data based upon the vehicle speed, and the degree of depression of the accelerator pedal (9). The second electric motor (3), is able to be connected to the wheels by a second controllable clutch-sleeve (5) which is controllable by the management unit during mode changing. The two clutch-sleeves, and their respective drive shafts (42,52) are fixed to each other.

Description

Third-party disclaimer English Abstract to the parallel type and vice versa.

Hybrid-type motor vehicle comprises at least two energy sources, ie the primary fuel-gasoline or diesel oil for example-which supplies the heat engine and the electricity supplying power to the electric motors, these two sources being able to independently or simultaneously propel the vehicle.

The series hybrid architecture, where the electrical power of the heat engine and that of the associated electric motor are added to the power of the battery to power the other electric motor connected to the wheels, allows a great flexibility of use of the engine for low power in urban use.

The parallel hybrid architecture, where the mechanical power of the heat engine is added to the electrical power of the associated electric motor at the wheel level, requires a reducer or a gearbox, and an associated control for gear changes. It has good yields for medium and high power and for peri-urban and motorway applications.

The invention relates to a mixed hybrid vehicle, series / parallel type that combines the two architectures and whose control can combine the advantages of a low-speed hybrid series vehicle and those of a high-speed parallel hybrid vehicle.

Currently, a series-type hybrid vehicle is described in US Patent 5,845,731A, filed in the name of CHRYSLER, comprising a heat engine, two clutches, two electric motors that serve together for the propulsion of the vehicle with the engine and a storage element. When the vehicle is operating in all-electric mode, both electric motors can participate in pulling the vehicle. Since one of the two electric motors is always connected to the wheels of the vehicle by construction, no-load losses are generated, which requires its oversizing for the apparent power because it must both ensure the start of the vehicle and accompany it. at its maximum speed.

The control of the modes of operation of this vehicle is specific: on the one hand the speed of the first electric motor "permanently at the wheel does not need to be canceled, regardless of the speed of the vehicle, and other Apart from the second electric motor linked to the engine and called generator, must be detached from the first electric motor and secured to the engine when it starts.

This solution described in the US patent has the disadvantage of not dealing with the problem of the synchronization of the different regimes of the two electric motors and the engine when the vehicle changes transmission mode of the parallel type to the series type and vice versa, or even when phases of change of state of the two clutches. In addition, this solution does not propose a method of charging or discharging electric motors, in order to avoid the torque holes during mode changes.

The invention aims to overcome these drawbacks by proposing a new architecture and a control method of a hybrid vehicle realizing the change of the transmission mode from the serial type to the parallel type and vice versa, while continuously ensuring the torque demand of the driver. .

For this purpose a first object of the invention is a powertrain for a vehicle with hybrid electric transmission, comprising a heat engine mechanically secured to a first electric generator motor, associated with a first clutch-clutch controllable to transmit power to the wheels in the mode parallel hybrid, and a second electric motor for transmitting power to the wheels in hybrid series mode, a battery supply of the two electric motors and a supervisory type electronic control unit receiving the speed information of said three motors and issuing them the instructions of torque as a function of the speed of the vehicle and of the depression of the accelerator pedal, characterized in that the second electric motor is capable of being connected to the wheels by a second clutch-clutch controllable by the supervisor during changes fashion, and that these two dog clutches o their respective driven shafts, which are connected to the wheels, mechanically secured.

A second object of the invention is a control method of the powertrain characterized in that, during the change of hybrid mode, serial type to the parallel type and vice versa, the supervisor controls an intermediate mode comprising the following phases - synchronization of the regime an electric motor which is not mechanically connected to the wheels in the initial hybrid mode on a speed proportional to the speed of the other electric motor which drives the wheels via one of the two clutch-clutches initially glued; - Activation of the other clutch-clutch initially detached, making the engine and the two electric motors secured to the wheels; - Gradual variation of the torque setpoints of the three motors from values in initial mode to values calculated for the mode to be reached - deactivation of the clutch-clutch initially glued when the torque setpoint, sent to the electric motor driving the wheels in the initial mode becomes null.

Other features and advantages of the invention will appear on reading the description of an exemplary embodiment of a powertrain, illustrated by the following figures which are: FIG. 1: a schematic diagram of a powertrain series / parallel hybrid vehicle according to the invention; FIG. 2 is a flowchart representative of an example of a control method according to the invention.

According to FIG. 1, the architecture of a hybrid serial-parallel-type powertrain consists of an internal combustion engine 1 associated, by a rotation shaft 12, with a first electric motor called generator 2, and secondly a second electric motor 3, electrically connected to the first electric motor 2 and an electric battery 6. Two systems 40 and 50 ensure the transmission of at least a portion of the output power of the two electric motors 2 and 3 respectively to at least one wheel 10 of the vehicle, their respective output shafts 41 and 51 being able to be coupled to the wheels each by means 4 and 5, electronically controllable by means of control circuits 44 and 45. For this purpose the architecture therefore also comprises a first coupling means 4, of the clutch-clutch type for example, capable of connecting the output shaft 41 of the transmission system 4 0 to the wheels 10 of the vehicle and through which the engine 1 alone or at the same time as the generator 2 provides power to the wheels 10 in parallel hybrid mode. It further comprises a second clutch-clutch coupling means 5, capable of connecting the second electric motor 3 to the wheels 10 to which it provides power in hybrid series mode, via the output shaft. 51 of the transmission system 50. The output shafts 42 and 52 of the two clutches 4 and 5, which are connected to the wheels 10 and intended to be driven by the motor parts 43 and 53 of said clutches, are integral with one of the other.

Finally, an electronic control unit 8, of the supervisor type, receives information on the NMT, NG and NME regimes of the three motors 1, 2 and 3 from tachometric elements 13 and 14 respectively, on the state EB of the battery 6 and on the state E4 and E $ of the clutch-clutch 4 and 5. By convention, when the clutches are glued, their state is equal to 1, - E4 = 1 or ES = 1 -, and when they are disabled , their state is equal to 0, - E4 = 0 or E $ = 0 -. This supervisor 8 also receives information on the torque request desired by the driver of the vehicle, from the depression of the accelerator pedal 9 or that of the brake, as well as information on the speed V "of the vehicle. vehicle from a sensor 7 for example.

On the basis of this information, the control unit 8 assigns the three motors 1, 2 and 3 torque sets CMT, Cc and CME respectively with the aim of optimizing the overall efficiency of the vehicle's traction chain and minimizing fuel consumption and the emission of pollutants, and pilot the two dog clutches 4 and 5 which may or may not be glued. The second object of the invention is a method of controlling this powertrain whose architecture has just been described, consisting in calculating the torque setpoints of each of the three engines and controlling the two clutch-clutches whose states characterize the different modes of operation of the power train. Thus, this supervisor makes it possible to operate the powertrain according to different modes, either the hybrid series mode or the parallel hybrid mode, with an intermediate mode corresponding to the bonding of the two clutch-jaw ensures a transition without torque shock.

In the hybrid series mode, there is first of all the operation in "all electric", at low speeds. When the state of charge of the battery 6 is deemed satisfactory by the supervisor 8 which keeps the heat engine 1 stopped, the second electric motor 3 draws energy from said battery 6 for the purpose of transmitting power to the wheels 1 via the second clutch-clutch 5, during acceleration phases. In the deceleration phase, the electric motor 3 recovers a portion of the variation of the kinetic energy to charge the battery.

The series hybrid mode with the combustion engine on is controlled by the supervisor 8 when it considers that the battery can not supply enough energy to the electric motor 3 to satisfy the torque demand formulated by the driver. To increase the power to the wheel provided by this electric motor 3, via the second clutch-jutch 5, the heat engine 1 provides power to the generator 2, which transmits it to the second electric motor 3, the first clutch-clutch 4 being disengaged.

Conversely, the battery 6 can store the power from the electric generator 2 which is not used by the electric motor. The control unit 8 calculates the power demanded from the heat engine 1, taking into account the state of the vehicle defined by various parameters such as the torque applied to the wheel, the vehicle speed Vv and the state of the battery, characterized by its state of charge, the output voltage, the intensity of the current flow and the temperature. The supervisor deduces the CMT torque setpoint to be applied to the engine, as well as the NMT setpoint of the corresponding shaft 12, placing this engine optimally, in order to minimize fuel consumption and the emission of pollutants. steady state.

From this NMT regime setpoint to be respected, the supervisor 8 derives the torque setpoint C <B> G </ B> from the generator 2 application of a control algorithm, of integral proportional type or with internal model example.

In addition, to ensure the torque demand to the wheel, desired by the driver and interpreted from the position of the accelerator pedal, the control unit 8 calculates the torque setpoint CME of the electric motor connected to the wheels.

These setpoints in torque and speed are calculated taking into account the limits of the different components of the powertrain, in particular the battery 6.

When the vehicle speed increases and reaches a certain threshold, automatically or by action of the driver on the mode selector 90, the power train operates in parallel hybrid mode. In this case, the second clutch-clutch is deactivated while the first clutch-clutch 4 is glued and the power supplied to the wheels 10 comes from the engine 1 assisted by the generator 2 which draws energy from the battery 6. If the electric charge of the battery is insufficient, the heat engine 1 provides power to the wheels and the generator 2 which recharges the battery 6. This is done to minimize fuel consumption.

The supervisor 8 calculates the different torque and speed setpoints to be applied to the three engines, in order to minimize the consumption, in stationary mode, while managing the limits of the various components. In particular, the speed of the electric motor 3 is canceled by a servocontrol.

In these two hybrid modes, the starting and stopping of the engine 1 are based on a threshold power or speed of the vehicle, taking into account the state of the battery 6 and the state of the vehicle , the speed and the requested torque. This variable threshold is calculated by the control unit to minimize fuel consumption.

The second object of the invention relates to the control of the powertrain which performs the change of operating mode, ie the transition from serial hybrid mode to parallel hybrid mode and vice versa, continuously ensuring the demand of the driver and avoiding torque shocks. The state of the two dog clutches characterizing the current mode, the change of mode passes through an intermediate mode characterized by the simultaneous bonding of the two clutches.

The flowchart of FIG. 2 represents the different successive steps of the control method ensuring the transition from the hybrid serial mode to the parallel hybrid mode and vice versa. The steps are symbolized by cartridges and states by rectangles. Step X corresponds to the all-electric hybrid series mode, the engine being stopped, the clutch 4 deactivated and the clutch 5 glued. When the power demanded at the wheel by the driver is greater than a threshold Pde, the starting of the engine is controlled by the supervisor, the clutches 4 and 5 being in the same state, in step Y.

Thus, the control of the passage of the hybrid series mode, wherein the first clutch-clutch 4 between the generator 2 and wheels is disengaged (E4 = while the second clutch-clutch 5 between the electric motor 3 and the wheels 10 is glued ( E5 = 1), to the parallel hybrid mode comprises the following steps.

first step a) consists in making the decision of this mode change after comparing the speed of the vehicle with a threshold or the power demanded from the wheel with a power threshold that depends on the state of the components, battery motors.

A next step b) of preparing for clutch clutch 4 is to bring the speed of the driving part 43 of said clutch, which is connected to the output shaft 41 of the transmission system to a value close to the speed of the clutch. driven shaft 42, which is connected to the wheels 10 driven by the electric motor 3. This is obtained by a servocontrol of the NMT regime of the engine, and therefore the N regime, 3 of the generator 2, at a rate proportional to the NME regime of the electric motor 3 which drives the wheels, to ensure synchronization two parts clutch-clutch 4 initially unstuck.

This slaving of the NMT regime is obtained by calculating the torque setpoints of the three engines, which takes into account the limitations of the various components of the powertrain and which maintains as much as possible a level of power of the constant heat engine to minimize stresses on the battery 6 and ensure driver demand through the electric motor 3.

Before authorizing the clutch clutch 4, the supervisor checks in step c), the speed of the vehicle VV is greater than a speed VPHS threshold giving priority to the serial mode in parallel mode. Indeed, the parallel hybrid mode is not exploitable for all vehicle speeds, particularly for very low speeds at which the engine may stall, the process gives priority to the hybrid mode series to separate the engine as soon as possible . In particular, during a strong deceleration, the speed of the vehicle can pass below VPHS threshold while the mode change is in progress.

When the regimes N42 and N43 of the two parts 42 and 43 the clutch-clutch 4 are substantially equal, which is found in step d) of comparing the difference between the measured speed of the driving part 43 and the operating mode. setpoint of the driven shaft 42, with a threshold this clutch 4 is activated by the supervisor 8, which makes the three heat engines 1 and 2 and 3 electrically secured by the transmission thus rotating at the same time (step e)). For this, the supervisor controls a circuit 44 for controlling the clutch.

When in return, the control unit 8 receives the activation information of said clutch 4 by the control circuit 44 (step f)), it performs a step g) of commutation of the torque instructions CMT, and CME of the three motors 1, 2 and 3 which will vary progressively from the values in series hybrid mode to values calculated for the parallel hybrid mode. This gradual variation avoids being hampered by the dynamics of the thermal engine which is the slowest, while ensuring the management of the limits of the components. The supervisor 8 makes the torque of the electric motor 3 turn towards a zero value and modifies the torque setpoint of the generator 2 to pass all the energy of the heat engine 1 by the mechanical transmission, while constantly monitoring the torque demand at the wheel expressed by the driver. Thus the torque shocks are avoided for the comfort of the driver of the vehicle.

However, if during this setpoint switching phase, the supervisor 8 finds that the speed V "of the vehicle is lower than the preceding VPH threshold (step o)), in case of braking for example, it reverses this switching to return to the series mode setpoints (step p)) As soon as in step q), the setpoints correspond to a zero torque T4 resulting from the generator 2 and the heat engine 1, the supervisor controls the take-off of the dog clutch 4 = 0, ES = 1) for the vehicle to operate again in serial hybrid mode (step r)).

When the supervisor 8 has commanded a zero torque setpoint for the electric motor 3, he verifies in step h) that the speed of the vehicle V is greater than a threshold VHP2, said speed threshold for the servocontrol of the electric motor and the interconnection of the clutch 5. Indeed, in case of sudden braking example, while the clutch 5 would have been disabled, its interconnection would be too long and adversely affect the safety of the vehicle.

After step h) for comparison of the speed, the second dog clutch 5 is deactivated (E5 = 0) while the first clutch 4 is activated (E4 = 1), so that the vehicle operates in parallel hybrid mode ( step i)).

When the control circuit 54 of the clutch 5 gives the deactivation information to the supervisor 8 in the step j), the latter returns to zero the NME regime of the electric motor 3 by means of the servo-control, then deactivates this motor to avoid the no-load losses (step k)) The control of the passage of the parallel hybrid mode, in which the clutch-dog clutch 4 is activated (E4 = 1) unlike the second dog clutch-clutch 5 (E5 = 0), to hybrid mode series, comprises the following other steps. The decision of the change of mode takes place after comparing the speed of the vehicle V V with a threshold VsH, which depends on the state of the battery 6, or the power demanded from the wheel, in step A).

The preparation for the clutch-dog clutch 5 interconnection consists of a step B) of servocontrol of the NME regime of the electric motor that does not rotate and is disconnected from the wheels 10, at a proportional regime to the NG of the generator 2, so the heat engine 1, which drives the wheels. Thus, the speed of the driving part 53 of the clutch 5, which is connected to the output shaft 51 of the transmission system 50 between the electric motor 3 and the wheels 10, is brought to a value close to the speed of the driven shaft 52 which is itself connected to the wheels that the generator 2 drives. Thus two parts 52 and 53 of the clutch 5 are synchronized.

To achieve this servocontrol of the NME regime, the supervisor 8 calculates torque instructions CMT, CEE and CME, which take into account the limitations of the three motors 1, 2 and 3 and the battery 6 and which ensure the driver's request through of the engine 1 and the generator 2.

The next step C) makes a comparison of the difference between the measured NME speed of the electric motor 3 and the speed N52 setpoint the driven shaft with a threshold SN2, and if this difference is well below said threshold, the supervisor 8 the clutch 5 is controlled by means of its control circuit 54 (step D)), since the speeds of the two portions 52 53 of the clutch 5 are substantially equal. The motors are then secured in rotation.

In step E), the control unit 8 reads the information on the state of the clutch 5 sent by its control circuit 54 and compares the speed of the vehicle with a threshold VHP, which is a function of the state of the battery and the vehicle, below which it triggers a step F) for switching the torque setpoints of the three motors. To avoid torque holes, the setpoints in parallel mode gradually change to serial mode values, while managing the powertrain component limit. When the setpoints correspond to a resulting zero torque T4 generator 2 and the heat engine 1 in step G), the supervisor controls the deactivation of the clutch 4 for the vehicle to operate in hybrid mode series (step H)).

When the control circuit 44 of the clutch 4 gives the information (E4 = 0) to the supervisor 8, the latter 8 controls the NG mode of the setpoint generator in series hybrid mode (step I).

Thus, during the change of hybrid mode, the supervisor controls the intermediate mode, during which are realized - the synchronization of the speed of the electric motor which is not mechanically connected to the wheels in the initial hybrid mode on a regime proportional to the speed of the other engine electric driving the wheels via one of the two clutches-jab initially glued; the activation of the other clutch-clutch initially detached, rendering the engine and the two electric motors secured to the wheels; the progressive variation of the torque setpoints of the three motors from the values in initial mode to values calculated for the mode to be reached; - Deactivation of the clutch-clutch initially glued when the torque setpoint, sent to the electric motor driving the wheels in the initial mode, becomes zero.

The architecture of the powertrain according to the invention combines the advantages of hybrid low-speed serial hybrid mode of the vehicle and high-speed parallel hybrid mode. Thanks to its control method which, during the change of mode, realizes an intermediate mode in which the two dog clutches are activated, the demand of the driver is ensured continuously, without holes of torque since the three motors are made integral with the wheels. same time.

While keeping a simple transmission system, gearbox type, the powertrain control minimizes fuel consumption and pollutant emissions, while ensuring a comfortable driving vehicle.

 The fact to separate the electric motor from the wheel through a second clutch-clutch reduces its size. This electric motor is no longer linked to the wheel at high speed, in parallel hybrid mode, and the reduction ratio between said motor and the wheel is shortened and avoids a high maximum torque of this engine, as well as no-load losses since its regime is regulated to a zero value.

Claims (2)

<B> <U> CLAIMS </ U> </ B> A power train for a vehicle with a hybrid electric transmission, comprising a heat engine mechanically secured to a first electric motor generator, associated with a first clutch-clutch controllable to transmit power to the wheels in parallel hybrid mode, and a second electric motor for transmitting the power to the wheels in the hybrid series mode, a battery supply of the two electric motors and a supervisor-type electronic control unit receiving the speed information of said three motors and delivering them the torque setpoints according to the speed of the vehicle and depressing the accelerator pedal, characterized in that the electric motor (3) is capable of being connected to the wheels (10) by a second clutch-clutch (5) controllable by the supervisor (8) during fashion changes and that these two dog clutches (4 and 5) have their shafts trained specifiers (42 and 52), which are connected to the wheels (10), mechanically secured. 2. Powertrain control method according to claim 1, characterized in that, during the change of hybrid mode from serial type to parallel type and vice versa, the supervisor (8) controls an intermediate mode comprising the following phases - synchronization the speed of the electric motor which is not mechanically connected to the wheels in the initial hybrid mode on a regime proportional to the speed of the other electric motor which drives the wheels (10) via one of the two clutches-claws originally <B > glued; </ B> - activation of the other clutch-clutch initially detached, making the engine (1) and the two electric motors (2 and 3) integral with the wheels <B>; </ B> - progressive variation torque setpoints of the three motors from the values in initial mode to values calculated for the mode to be reached; - Deactivation of the clutch-clutch initially glued when the torque setpoint, sent to the electric motor driving the wheels in the initial mode, becomes zero. Powertrain control method according to claim 2, characterized in that, during the transition from serial hybrid mode to parallel hybrid mode, the supervisor (8) controls an intermediate mode comprising the following steps: a) decision making of the change of the hybrid mode mode after comparing the vehicle speed (V,) with a threshold (VHS), depending on the state of the components; b) control of the speed (NMr) of the engine (1) and the speed (NG) of the generator (2) at a speed proportional to the speed (NME) of the electric motor (3) by calculating the torque setpoints of the three motors so synchronizing the driving part (43) on the driven part (42), connected to the wheels (10), of the clutch (4) initially taken off <B>; </ B> comparison of the speed (V,) of the vehicle with a threshold giving priority to the serial mode in the parallel mode; comparing the speeds of the two driving parts (43) driven (42) of the clutch-clutch (4) detached; e) activation of said clutch (4) which renders the three motors (1, 2, secured by the transmission, f) receiving the activation information of said clutch (4) by supervisor (8); g) gradually switching the torque setpoints of the three motors (1, 2, 3) to values calculated for the parallel hybrid mode, if the vehicle speed remains above the threshold (VPHS); h) comparing the speed of the vehicle with a threshold (VHP2), for the authorization of takeoff of the second clutch-clutch (5) initially activated in step i); j) receiving the deactivation information of said clutch (5) by the supervisor (8); k) deactivation of the electric motor (3) to eliminate empty losses. 4. Powertrain control method according to claim 3, characterized in that, during the step of switching the torque setpoints of the three motors, the supervisor (8) performs the following steps o) speed comparison (Vy ) the threshold vehicle (VPHS); p) reversing the setpoint switching for a return to the hybrid series mode if the vehicle speed (V ") is below the threshold (VPHS), q) verifying that the setpoints correspond to a resulting zero torque generator (2) and the thermal engine (1); r) take-off of the clutch-clutch (4) activated in the preceding step e) 5. Control method of the powertrain according to claim 2, characterized in that, during the passage of the parallel hybrid to the serial hybrid mode, the supervisor (8) controls an intermediate mode comprising the following steps A) decision making mode change after comparing the speed of the vehicle (V,) with a threshold (VSH), depending on the state of the battery (6), B) the speed control (NME) of the electric motor (3), disconnected from the wheels (10), at a rate proportional to the speed (Nc;) of the generator (2), causing the wheels, by calculating the torque setpoints of the three engines (1, 2, 3), for synchronizing the drive part (53) of the clutch (5) initially detached on its driven part (52) connected to the wheels; C) comparing the speeds of the two driven (53) and driven (52) portions of the clutch (5) unstuck; D) activating said clutch (5) which makes the three motors, 2, 3) integral with the transmission; E) reception of the activation information of said clutch by the supervisor (8) and comparison of the vehicle speed (V,) with a threshold (VHP), progressive switching of the torque setpoints of the three motors (1, 2, 3) to values calculated for the serial hybrid mode; verifying that the setpoints correspond to a zero torque resulting from the generator (2) and the heat engine (1); deactivating the clutch (4) initially glued in parallel mode; control of the speed (NG) of the generator (2) to its setpoint in series mode.