FR3061688A1 - METHOD FOR CONTROLLING A DECELERATION HYBRID MOTOR POWERTRAIN - Google Patents

Abstract

A method for controlling the regenerative braking of a hybrid powertrain where the braking demand expressed by the driver by pressing his brake pedal is distributed by a brake control system (BSM) between the brakes of the vehicle and an electric machine operating generator for recharging the battery, characterized in that during a change of state of the kinematic chain involving the interruption of the transmission of the regenerative braking torque of the electric machine to the wheels, the regenerative braking torque (EM Wheel tq brake req) is temporarily transferred by the brake control system (BSM) to the vehicle brakes.

Description

Holder (s): RENAULT S.A.S, NISSAN MOTOR CO. LTD ..

O Extension request (s):

® Agent (s): RENAULT SAS.

FR 3 061 688 - A1 ® CONTROL METHOD FOR HYBRID DECELERATION DRIVE GROUP. @) Method for controlling the regenerative braking of a hybrid powertrain where the braking request expressed by the driver by pressing his brake pedal is distributed by a braking control system (BSM) between the vehicle brakes and an electric machine operating as a generator to recharge the battery, characterized in that during a change of state of the kinematic chain involving the interruption of the transmission of the regenerative braking torque from the electric machine to the wheels, the regenerative braking torque (EM Wheel tq brake req) is temporarily transferred by the brake control system (BSM) to the vehicle brakes.

- i CONTROL METHOD FOR HYBRID DECELERATION MOTOR-PROPELLER

The present invention relates to the control strategies implemented in vehicles equipped with hybrid powertrains (GMP).

More specifically, it relates to a method for controlling the regenerative braking of a hybrid powertrain in which the braking demand expressed by the driver by pressing his brake pedal is distributed by a braking control system, between the brakes of the vehicle. and an electric machine operating as a generator to recharge the battery.

A hybrid vehicle equipped with an electric machine usually has energy recovery periods during decelerations, thus taking advantage of the kinetic energy of the vehicle to generate electricity, by applying negative torque to the wheel. using the electric machine, then acting as a generator.

On certain hybrid applications, a technology called “decoupled braking” is integrated. It distributes between the wheel brakes and the electric machine, the level of deceleration requested by the driver by pressing his brake pedal. The kinetic energy is no longer entirely lost by the friction of the pads on the brake discs / drums, but used in part or in whole by the electric machine, to recharge the vehicle battery.

The vehicle's drive train is defined by a combination of couplers and reducers, specific to each architecture. When the kinematic chain changes states, the electric machine can be momentarily decoupled from the wheels, to allow the gear ratio to be changed. When this change of state occurs during the braking phase with energy recovery, the recovery is temporarily canceled, causing loss

- 2 of the deceleration level achieved by the electric machine. During such a change of state, the actual deceleration of the vehicle no longer corresponds to the deceleration request from the driver.

The publication FR 2 973 299, for example describes a hybrid transmission for a motor vehicle provided with a heat engine and an electric drive machine, which comprises two primary eccentric shafts and a secondary shaft carrying two gear gears and a coupler . The coupler makes it possible to link the electric machine to the wheels on two transmission ratios, in electric or hybrid mode. It opens to allow a change between these reports by temporarily interrupting the transmission of torque (engine or resistant) to the wheels, during the shift. If the vehicle is decelerating, the actual deceleration of the vehicle no longer corresponds to the driver's request for deceleration.

The present invention aims to guarantee a constant level of deceleration in a braking situation, during a change of state of the kinematic chain involving a breakdown of electrical torque at the wheels.

To this end, it proposes that during a change of state of the kinematic chain involving the interruption of the transmission of the regenerative braking torque from the electric machine to the wheels, the regenerative braking torque is temporarily transferred by the brake control, to the vehicle brakes.

Preferably, the transfer takes place before the start of the change of state.

This method can be used on all hybrid vehicles equipped with an automatic transmission, the kinematic chain of which has at least two states, the change of which involves a breakdown of electrical torque at the wheels.

The invention will be better understood on reading the following description of a nonlimiting embodiment

- 3 thereof, with reference to the accompanying drawings, in which:

FIG. 1 is an example of the electronic architecture used, and

Figures 2 and 3 illustrate the progress of the proposed strategy.

The terms of electronic architecture which appear in FIG. 1 are vehicle control units:

• BSM: Control of the braking system, • TSM: Control of the distribution of torque setpoints, • ASC: Control of the target kinematic chain state • EM: Electric machine.

The signal flows used are defined as follows:

• Brake pdl pressure: Driver's braking pressure on the brake pedal, • EM Wheel tq brake req: Electric torque at the wheels required by the Brake System Control (BSM), • EM Wheel tq brake applied: Electric torque at the wheels being applied by the Torque setpoint distribution control (TSM), • EM tq req: Electric torque requested from the machine

electric (EM) by Control of the division of torque settings (TSM), • EM wheel tq brake reg: Flag of application of electric torque wheel braking by Control of the distribution of instructions (TSM) of linked couple at EM Wheel tq brake req.

• DLS setpoint: State of the target kinematic chain sent by the Control of the target kinematic chain state to the gearbox and other consuming functions, • Shift with EM wheel tq break: Flag of change of state of the kinematic chain with breaking of torque to come or in progress, • Gearbox tq reg: Box intervention flag

- 4 speed on the torque setpoints, • Hydro wheel tq brake req: braking torque setpoint to be achieved by the hydraulic braking system, • Global wheel tq brake applied: overall level of braking torque achieved at the wheel by the hydraulic system and by electric machine.

As indicated above, on a hybrid vehicle in the "regenerative braking! F" phase, the braking is distributed between the vehicle brakes and the electric machine operating as a generator to recharge the battery. The method of the invention controls the distribution of the braking demand expressed by the driver by pressing his brake pedal by a braking control system (BSM) between the brakes of the vehicle and the electric machine. So that the cancellation of the negative torque of the electric machine required by the braking system is not felt by the driver and his passengers during a change of state of the kinematic chain involving the opening of the torque chain between the electric machine and the wheels, the regenerative braking torque (EM Wheel tq brake req) is temporarily transferred by the braking control system (BSM) to the vehicle brakes. To this end, provision is made for the braking control system (BSM) to transfer the regenerative braking request EM Wheel tq brake req to the hydraulic braking system, generally hydraulic. The transfer preferably takes place before the start of the change of state. It is carried out by the request Hydro wheel tq brake req, mentioned in FIG. 2, which is a request for hydraulic braking in the nonlimiting case, where the braking system of the vehicle is hydraulically controlled.

To achieve this, the Control of the target kinematic chain (ASC) produces and first issues a Flag Shift with EM wheel tq break, to warn the Brake System Control (BSM) of a change of state of the kinematic chain imminent or in progress, with rupture

- 5 of torque on the electric machine.

The Flag Shift with EM wheel tq break passes to the true value, if the future state (target state DLS target) of the kinematic chain chosen by the Control of the state of the kinematic chain (ASC), implies a break in electrical torque to the wheels, when engaged from the current DLS_crt state.

The Control of the target drive train status (ASC) keeps the target setpoint of the final target drive drive DLS setpoint (implemented in all other software functions) at its initial value at this stage. This setpoint is different from DLS target. It is retained until the Brake System Control (BSM) has canceled its request for electrical braking torque at the EM Wheel tq brake req. The overall level of braking torque remains constant during the transfer, since the increase in the braking torque setpoint at the wheels is the reverse of the decrease in the regenerative braking setpoint.

When the demand for electrical braking torque at the wheels becomes zero, and the Braking System Control (BSM), has regulated the overall braking torque level, transferring the torque previously achieved by the electric machine EM Wheel tq break applied in a Hydro wheel tq brake req hydraulic torque produced by the braking system, the Setpoint Distribution Control (TSM) emits an EM wheel tq brake reg signal at the false value, intended for the Control of the target kinematic chain status ( ASC). The change of state begins at the moment when the braking transfer is carried out.

The Target Kinematic Chain State Control (ASC) chose the chain state of the final DLS setpoint kinematics, according to its own internal strategies. For reasons of approval or reliability of the powertrain components, it may not wait for the emission of the EM wheel tq brake reg flag at the false value to impose

- 6 the emission of the target state. The change of state begins in particular before the electric braking torque is canceled, if the maintenance of the current state of the kinematic chain imposes an under-speed or an overspeed of the traction elements (electric machine or heat engine), or if it becomes unavailable due to malfunctions of the gearbox or of the bodies involved in its production.

In this case, an internal flag, called No shift delay for tq brake reg, is produced and imposed internally on the Control of the target kinematic chain state (ASC).

The No shift delay for tq brake reg signal goes to the true value if:

the DLS setpoint state imposes a sub-regime or an overspeed of the traction units (electric machine or heat engine), or if it becomes unavailable due to malfunctions of the gearbox or of the organs participating in its production, if ( so that driving pleasure is retained);

if the Braking System Control (BSM) takes longer than a certain time to cancel its request for electric braking torque at the wheels EM Wheel tq brake req after the Shift with EM wheel tq break flag is set to the value true, the change of state is triggered before the electric braking torque is canceled; this is the case in particular, if the Braking System Control (BSM) takes too long to cancel its request for electrical braking torque at the wheels, for the driving pleasure to be retained;

or if the Control of the target kinematic chain state is in manual mode, implying that no holding delay can be envisaged, without degrading the driving pleasure.

When receiving the signal No shift delay for tq brake reg to the true value, or from the signal EM wheel tq brake reg to the false value, the Control of the kinematic target state (ASC) applies the state of

- 7 the target drivetrain DLS target previously saved through the final drivetrain state DLS setpoint, so that the driveline status can be achieved by the gearbox and that all other consuming software functions of this information could work properly.

The flag Shift with EM wheel tq break is maintained at the true value, as long as the change of state of the kinematic chain DLS setpoint is not finished: this condition is defined by the fact that there is equality between the state of the drive train DLS crt current and the drive train target DLS setpoint current and the fact that the gearbox has no influence on the torque setpoints issued by the Torque setpoint distribution control (the flag Gearbox tq reg having the false value in this case).

Figure 2 illustrates how the strategy works step by step. In step 1, the state of the target kinematic chain DLS target changes and its realization implies a break in electrical torque to the wheel lasting from the state of the current kinematic chain DLS crt. The Shift with EM wheel tq break signal is then set to true. It is received by the Braking System Control (BSM) which decreases its torque request to the electric wheel EM Wheel tq brake req to have this torque achieved by the hydraulic braking system (Brake System), through its setpoint Hydro wheel tq brake req. During steps 1 and 2, the overall level of braking torque Global wheel tq brake applied remains constant, since the increase in the Hydro wheel tq brake req setpoint is the reverse of the decrease in the EM wheel tq brake setpoint req.

In step 2, the EM Wheel tq brake req electrical braking setpoint becomes zero, which allows the Torque setpoint distribution control (TSM) to pass the EM wheel tq brake reg signal to the false value. In step 2, the kinematic chain status control (ASC) sends the final target kinematic chain status signal DLS setpoint to the gearbox and to the other functions necessary for its realization, which starts at this point. instant. The gearbox then begins to realize it by intervening on the torque setpoints issued by the Torque setpoint distribution control (TSM) which then transmits this information by the Gearbox tq reg signal, which then changes to the true value. It takes control over the distribution of torque setpoints issued by a torque setpoint distribution control system during the change of state.

In step 3, the current kinematic state DLS crt becomes equal to the final target kinematic state DLS setpoint. The gearbox always keeps control of the distribution of the torque setpoints issued by TSM, which continues to issue the Gearbox tq reg flag accordingly at the true value.

In step 4, the gearbox no longer has control over the distribution of the torque setpoints, which implies passing the Gearbox tq reg flag to the false value. Therefore, the Control of the target kinematic chain (ASC) status switches the signal Shift with EM wheel tq break to the false value to allow the braking system (BSM) to again request an electric braking torque EM Wheel tq brake req at the Torque setpoint distribution control (TSM) and have some of the hydraulic braking performed by the electric machine.

Between stage 2 and stage 4, no braking is carried out by the electric machine, but only through the hydraulic system and the Hydro wheel tq brake req setpoint. From step 4, up to step 5, the Brake system control increases its request for electric braking via the signal

EM Wheel tq brake req and the decrease in its braking request

Hydro wheel tq brake req, so that the overall level of braking torque at the wheel,

- 9 Global wheel tq brake applied, remains constant.

The braking control system again requests a regenerative braking setpoint from the braking setpoint distribution control system, after the change in state. In step 5, the brake system control finds itself in the same situation as before the step

1, which allows it to better distribute its EM Wheel tq brake req and hydraulic Hyrdo wheel tq brake req braking instructions, according to the driver's braking request.

FIG. 3 illustrates the case where the state of the DLS setpoint kinematic chain cannot be maintained so that the brake system control (BSM) cancels its request for electrical braking before the state of the DLS target kinematic chain is achieved. setpoint.

Step 1 is identical to the previous case. At the stage

2, the EM Wheel tq brake req electrical braking setpoint is still not zero. The signal No shift delay for tq brake reg goes from the false value to the true value, meaning that the state of the final target kinematic chain cannot be frozen at its initial value any longer, without causing a risk of degradation of the driving pleasure or endangering the traction equipment.

The kinematic chain status control (ASC) then sends the state of the final target kinematic chain DLS setpoint, to the gearbox and to the other functions necessary for its realization, which begins at this moment. The gearbox then begins to realize it by intervening on the torque setpoints issued by the Torque setpoint distribution control (TSM) which transmits this information by the Gearbox tq reg signal which is at true value. Unlike the previous case, the braking system has not finished canceling its electrical braking torque setpoint EM Wheel tq brake req by compensating for it with the Hydro wheel tq brake req setpoint: it then exists

- ίο a decrease in the overall braking torque at the wheel Global wheel tq brake applied even if this is minimized by the strategy in place before step 2. The following steps are the same as in the previous case.

The advantages of the invention are numerous. Among these, we can note:

• the little development that it requires, and the simplicity of its implementation, • its possible application on all hybrid architectures equipped with an automatic transmission having at least two kinematic chain states whose change implies a break in electrical torque at the wheels, and • the use of a decoupled braking system, making it possible to recover braking energy, with a good level of approval, on the hybrid architectures concerned.

- ii -

Claims (10)

1. Method for controlling the regenerative braking of a hybrid powertrain in which the braking request expressed by the driver by pressing his brake pedal is distributed by a braking control system (BSM) between the vehicle brakes and an electric machine operating as a generator to recharge the battery, characterized in that during a change of state of the kinematic chain involving the interruption of the transmission of the regenerative braking torque from the electric machine to the wheels, the regenerative braking torque (EM_Wheel_tq_brake_req ) is temporarily transferred by the brake control system (BSM) to the vehicle brakes. 2. regenerative braking control method according to claim 1, characterized in that the transfer of the regenerative braking request to the vehicle brakes, occurs before the start of the change of state. 3. A method of controlling regenerative braking according to claim 1 or 2, characterized in that the overall level of braking torque remains constant during the transfer, because the increase in the braking torque setpoint at the wheels is reverse of the decrease in the regenerative braking setpoint. 4. Recuperative braking control method according to claim 1, characterized in that the change of state begins at the moment when the braking transfer is carried out. 5. Regenerative braking control method according to claim 3, characterized in that the change of state begins before the electric braking torque is canceled, if the maintenance of the current state of the kinematic chain imposes a sub-regime or an overspeed of the traction units or if it becomes unavailable due to malfunctions of the gearbox or of the organs involved in its production. 6. Regenerative braking control method according to - 12 claim 3 in that the change of state is triggered before the electric braking torque is canceled, if the brake system control (BSM) takes too long to cancel its request for electric braking torque at the wheels , to maintain driving pleasure. 7. regenerative braking control method according to claim 1, 2 or 3 characterized in that the change of state is triggered before the electric braking torque is canceled if the control of the kinematic chain state is in manual mode . 8. A method of controlling regenerative braking according to claim 1, 2 or 3, characterized in that the gearbox takes control over the distribution of torque setpoints emitted by a system for controlling the distribution of torque setpoints during the duration change of state. 9. Regenerative braking control method according to claim 1, 2 or 3, characterized in that the braking control system again requests a regenerative braking instruction from the system for controlling the distribution of braking instructions, after the completion of the change of state. 10. Regenerative braking control method according to one of the preceding claims, characterized in that the vehicle brakes are hydraulically operated. 1/3