FR2957645A3 - System for controlling take-off phase of motor vehicle at time of action of driver on accelerator pedal, has generation module generating three setpoints utilized to control engine rotation speed and clutch torque - Google Patents

Abstract

The system has a generation module (1) for generating an engine rotation speed setpoint (omega-tgt), an engine torque setpoint and an input clutch torque setpoint (Cembtgt) from speed (V) of a vehicle (7), a position (P) of an accelerator pedal and wheel torque requirement (CHTA), where the three setpoints are utilized to control an engine rotation speed (omega) and an input clutch torque (Cemb). A rotation speed regulation device (4) regulates the engine rotation speed around the speed setpoint. An independent claim is also included for a method for controlling a movement phase of a vehicle at a time of an action of a driver on an accelerator pedal.

Description

The invention relates to a system and a method for controlling the movement phase, known as the "drive-in phase". of "take-off", of a motorized vehicle, and more generally of the transition phase from the open state to the closed state of an input clutch equipping the vehicle gearbox.

It relates to the field of automated gearless gearbox transmissions, such as automatic two-clutch gearboxes, or compact conical coupler gearboxes used in motor vehicles. On all transmissions of vehicles, whether manual or automatic, the takeoff consists in gradually passing to the wheels a certain level of the torque delivered by the engine. On a manual gearbox, the driver ensures progressive torque transfer by simultaneously manipulating the acceleration and clutch pedals. From the disengaged position, it meticulously checks the support on the accelerator pedal, to ask the engine a sufficient torque to the compensation of the vehicle load, and the release of the clutch pedal, to gradually close the input clutch so that the vehicle load is gradually seen by the engine. The precision of the dosing makes it possible to avoid runaway, stalling or jerking of the engine.

In the case of automated boxes, the driver only acts on the accelerator pedal, closing the input clutch being performed by a main coupler controlled by a computer associated with the gearbox. There are several ways to control the closing of the entry clutch take-off phase in the case of an automated box. The prior art describes for example a control method taking into account the difference 2957645 -2- between the rotational speed of the engine and the rotational speed of the input shaft of the gearbox, said primary regime. In a first phase, when the two regimes are remote, the torque transmitted by the input clutch to the wheels increases and the vehicle begins to move. Then, when the two regimes are close enough, the input clutch is closed and the vehicle enters the nominal driving phase. The disadvantage of such a method is that it provides a takeoff performance independent of the support on the accelerator pedal made by the driver. Other control systems and methods which overcome this disadvantage are known, in particular those which make it possible to regulate the primary or engine speed on a specific target, so as to guarantee a certain behavior of the vehicle during take-off, for example a rapid hit. the target speed of the vehicle, a limitation of jolts when the clutch closes, or a control of noise pollution related to the engine speed.

Although these methods take into account the support on the accelerator pedal, they only make it possible to guarantee only one of the desired criteria. In addition, they do not take into account the demand for torque to the wheels expressed indirectly by the driver via the depression of the accelerator pedal, which can in certain critical cases cause the engine to stall or create a shock. when opening the input clutch. The aim of the invention is to improve the take-off quality of automated gearboxes, by proposing a system and a control method making it possible to control the sliding of the input clutch when the vehicle is set in motion, so as to reach as quickly as possible a target speed of the vehicle, ensuring a limitation of the maximum engine speed and shocks during closing of the input clutch, taking into account the variations of support on the accelerator pedal and the level of torque to the wheels requested by the driver. It proposes to control in parallel the engine speed and the torque that can be transmitted to the input clutch, so that these two quantities are servocontrolled on reference trajectories describing the expected behavior during the take-off phase: the target of engine speed is designed to operate the engine at its maximum torque, while being saturated to avoid the 5 flights of regime; the target input clutch torque is smooth and not dynamic, to avoid jolts. in one embodiment, the invention relates to a control system of a phase of setting in motion, during the action of the driver on the accelerator pedal, a vehicle equipped with a motor transmitting a torque to a gearbox 10, via at least one input clutch whose control allows to connect or to decouple progressively in rotation a primary shaft with an output shaft of the motor. The control system comprises a module for generating an engine rotational speed setpoint, a motor torque setpoint and an input clutch torque setpoint, based on the speed of the vehicle. the position of the acceleration pedal and the torque demand to the wheels. It comprises a device for regulating the speed of rotation of the motor around a setpoint, and a device for regulating the input clutch torque around a setpoint.

Advantageously, the control system comprises an open loop for calculating an input clutch torque setpoint, another open loop for calculating a motor torque setpoint, and a closed motor control loop, which is controlled. from the sum of the motor torque setpoint and an adjustment torque.

For example, the adjustment torque is delivered by the regulating device. This makes it possible to take into account the external disturbances and to cancel the error between the setpoint value of the rotational speed of the engine and the measurement of the rotational speed of the engine. The setpoint generation module comprises a module for generating a filtered engine speed setpoint, a safety module, a closing module for the input clutch, means for generating a setpoint. motor torque, and a module for generating an input clutch torque setpoint.

For example, the module for generating the filtered engine speed setpoint comprises a map receiving input instructions according to the speed of the vehicle and the position of the accelerator pedal. A low-pass filter may be placed at the output of the map in order to smooth the engine rotational speed curve and to obtain a filtered engine speed setpoint.

The clutch module of the input clutch comprises a means for comparing the difference of the rotational speeds of the motor and of the primary shaft with a threshold, and means for generating a ramp setpoint so as to replace the set value of the filtered engine speed, in order to converge the rotational speed of the engine on the rotational speed of the primary shaft. This module eliminates shocks when closing the input clutch. According to a second aspect, the invention relates to a method of controlling a phase of setting in motion, during the action of the driver on the accelerator pedal, a vehicle equipped with a motor transmitting a torque to a gearbox 20, through at least one input clutch controlled by a control sequence for coupling or decoupling progressively in rotation a primary shaft with an output shaft of the engine. The control method is configured to develop a motor rotation speed setpoint, a motor torque setpoint, and an input clutch torque setpoint, from the vehicle speed, of the pedal position. acceleration and torque demand to the wheels, and to regulate in closed loop the motor torque from the motor torque setpoint and an adjustment torque capable of canceling the error between the setpoint and the measurement engine speed. Advantageously, a map is defined and modified by triggering a security module and a closing module of the input clutch. For example, the map can receive the input variations of the accelerator pedal and the vehicle speed values.

In addition, the rotational speed of the input shaft is compared with the reference of the rotational speed of the motor, and the closing module of the input clutch is switched on when the difference in the speeds of rotation of the motor and of the primary shaft is below a certain threshold. A ramp setpoint is generated for the rotational speed of the motor, so as to replace the engine rotation speed reference and to converge more slowly the rotational speed of the engine on the rotational speed of the shaft. primary. Preferably, the motor torque setpoint is a function of the input clutch torque, the motor inertia, and an acceleration setpoint of the motor, defined according to the fundamental law of the dynamics. The motor torque setpoint is a prepositioning setpoint, which makes it possible to regulate the rotational speed of the motor to its setpoint, in an open loop. The motor acceleration setpoint is obtained by deriving the motor rotation speed reference. The motor inertia is a mechanical constant (expressed for example in kg · m2) for connecting the angular acceleration of the motor output shaft and the engine torque. Other features and advantages of the present invention will become apparent upon reading the following description of a non-limiting embodiment thereof, with reference to the accompanying drawings, in which: FIG. An embodiment of the control of the takeoff phase of a vehicle, • Figure 2 shows an example of an embodiment of the generation of the instructions, and • Figure 3 shows the strategy of Closing a clutch at the end of take-off, and • Figure 4 shows the evolution of the input clutch torque during take-off.

According to FIG. 1, the method of controlling the take-off phase of a vehicle, during the action of the driver on the accelerator pedal, comprises a regulation generation module 1, two comparators 2 and 3, two PIb type regulating devices 4 and 5, an adder 6, and a block 7 representing the vehicle.

The module 1 for generating the setpoints makes it possible to generate a speed reference of the motor wtgt, a motor torque setpoint Cmottgt and an input clutch torque setpoint Cembtgt, comprising as input the bearing variations P on the acceleration pedal, the speed V of the vehicle 7, and the torque demand to the wheels CHTA expressed by the driver by the depression 15 of the accelerator pedal. This request for torque to the wheels is proportional to the depression of the accelerator pedal P. The comparator 2 is connected to the output of the module 1 for generating the setpoints, to a measurement sensor (not shown) of the rotation speed of the motor w and at the input of the control device 4. The adder 6 is connected to the output of the regulating device 4, to an output (Cmottgt) of the module 1 for generating the setpoints, and to the input of the vehicle 7 The comparator 3 is connected to the output of the setpoint generation module 1, to a measurement means (not shown) of the input clutch torque Cemb and to the input of the regulation device 5.

The control method makes it possible to regulate in closed loop the rotational speed of the motor w around the nominal value of the rotational speed of the motor wtgt. This wtgt instruction is developed to describe the behavior of the desired vehicle 7 in the takeoff phase. In order to take into account the external disturbances, the regulation device 4 makes it possible to cancel the errors between the setpoint wtgt and the measurement w by means of the comparator 2. More precisely, in closed loop, the measurement w is subtracted from the setpoint wtgt from the setpoint generation module 1, using the comparator 2, and the difference wtgt-w is transmitted to the control device 4. This device 4 outputs a setting torque Cm ), summed by the adder 6 to the engine torque setpoint Cmottgt from the module 1 generation instructions. The result of this summation Cmottgt + CPIp corresponds to a motor torque Cmot transmitted to the vehicle 7 so as to obtain, at the output of the vehicle 7, the rotational speed of the engine w. In parallel, the control method regulates in closed loop the input clutch torque Cemb around the setpoint Cembtgt, to transfer to the wheels a couple quite close to the one requested by the driver, that is to say CHTA, via the accelerator pedal, but having nevertheless undergone filtering and smoothing. More precisely, CHTA being directly proportional to the depression P of the accelerator pedal, all its variations would be felt brutally in the vehicle if it was transmitted to the wheels without this treatment. A limitation of the dynamics of the variation of the Cemb torque makes it possible to guarantee a good driving pleasure. In a closed loop, the measurement Cemb is subtracted from the setpoint Cembtgt from the setpoint generation module 1, using the comparator 3, and the difference Cembtgt-Cemb is transmitted to the regulation device 5, of the PID type. In Figure 2 is shown, for example, a module 1 for generating instructions. This module 1 for generating the setpoints comprises a module 8 for generating a value of rotational speed of the filtered motor wtgtF, a safety module 9, a closing module of the clutch at the end of take-off 10, a module 11 for developing the motor torque setpoint Cmottgt, and a module 12 for generating the input clutch torque setpoint Cembtgt. The module 8 for generating a filtered engine rotation speed reference Wt9tF comprises a cartography C supplied by the manufacturer, linking the maximum engine torque Cmmax to its rotation speed w, and a low-pass filter PB. The security module 9 comprises means for comparing the filtered engine rotation speed wt9tF with the value of the rotation speed of the primary shaft wp. The closing clutch module at the end of takeoff 10 comprises a comparator 13, a comparison means 14 and a means 15 for generating a ramp setpoint. The module 11 for developing the motor torque setpoint Cmottgt comprises a deriving means 16 of the engine rotation speed wt ~ + and a calculation module 17 of the engine torque setpoint Cmoffgt.

To reach the target speed of the vehicle 7 as quickly as possible, the engine must provide its maximum torque Cmmax. The performances of each engine are defined by a map C linking the maximum engine torque Cmmax to the rotational speed of the engine w, for each support value P on the acceleration pedal and for each speed V of the vehicle 7. The different bearings pedal 15 P possible and the different speeds V define a network of curves Cmmax = f (w). For a pedal support P and a given speed V of the vehicle 7, while seeking to make the motor operate at its maximum torque, the rotation speed reference of the motor w is thus defined by inverse function, according to the following equation: = f-1 (max (Cmmax)) The cartography C receives as input the variations of support of the acceleration pedal P and the velocity values V of the vehicle 7. The low-pass filter PB makes it possible to smooth the output of mapping C in order to obtain the rotational speed reference of the wt9tF engine. This instruction is then modified by the security module 9 and the closing module of the input clutch 10. The speed reference wt9tF from the module 8 is transmitted to the security module 9 which compares it with the measurement of the speed of rotation of the primary shaft wp and saturates it if the difference of schemes wt9tF - wp is negative. In other words, the rotation speed setpoint of the motor wt9t must always be greater than the rotation speed of the primary shaft wp, and the safety module 9 has output a setpoint wt9t which verifies the condition next: co tgtF Si ° tgtF 0) P ~ P si cotgtF <~ P 5 The rotation speed setpoint of the filtered motor Wt9tF from the module 8 is also transmitted to the closing module of the input clutch 10. The comparator 13 evaluates the difference between the rotation speed setpoint of the filtered engine Wt9tF and the rotational speed of the primary shaft wp. This difference wt9tF-wp is compared, using the comparison means 14, with a threshold value 5. When the difference wt9tF-wp is less than the threshold 5, the means for generating a ramp setpoint 15 for the rotational speed of the motor is switched on, so as to replace the value of the rotational speed reference of the filtered engine WtgtF. More precisely, under this threshold condition, the rotation speed setpoint 15 of the motor wt9t is no longer defined by the cartography C, but by the generation of a ramp function which converges more slowly the rotation speed of the engine. motor wt9t to the rotational speed of the primary shaft wp, to eliminate jolts when closing the input clutch. The ramp setpoint is also compared and saturated by the security module 9, 20 to obtain a motor rotation speed reference wt9t which is always greater than or equal to the speed of the primary shaft wp. The module 11 makes it possible to determine the Cmotte motor torque setpoint. This setpoint is directly related to the evolution profile of the rotation speed setpoint of the engine wt9t from the safety module 9, and is deduced from the balance of the pairs at the input clutch. The equation of the balance of the pairs is determined by the application of the fundamental law of the mechanics, according to the following equation: ct) tgt = 2957645 -10- is: Cmottgt Cemb + JmCbtgt (1) where Jm is the inertia the engine, to; acceleration of the motor, wtgt the motor acceleration setpoint, Cmot the engine torque, C, nottgt the engine torque setpoint, Cemb the input clutch torque measured.

The motor acceleration setpoint wtgt is obtained by numerically deriving the setpoint of the rotational speed of the engine cotgt from the safety module 9, by means of bypass 16. Then the module 17 calculates the motor torque setpoint Cmottgt according to the equation (1). The module 12 makes it possible to develop the input clutch torque setpoint 10 Cembtgt. It consists of a low-pass filter, which filters the torque to the CHTA wheels requested by the driver. Figure 3 illustrates the strategy of the module 10 closing the input clutch at the end of takeoff. On the ordinate, we find rotation regimes expressed in rads-1, and on the abscissa the time t expressed in seconds. The curve in solid line represents the rotational speed reference of the motor wtgt, and the dashed line represents the rotational speed of the primary shaft wp. At time to and until time tl, the rotational speed of the primary shaft is zero and the motor rotates at a slow rotation speed wl. The request to start the vehicle has not yet been made by the driver.

From time t1, the clutch is no longer open, so that the engine torque begins to pass to the wheels of the vehicle. The curve of the rotational speed of the primary shaft wp first increases slowly, then exponentially, and the curve of the rotational speed reference of the motor wtgt evolves according to a logarithmic function, given by the mapping C of the module 8 To a value of rotation w2, then remains constant until time t2. At time t2, the difference wtgt-wp of the speed of rotation of the primary shaft wp and the speed reference of the output shaft of the motor wtgt reaches a threshold 5, and the closing module of the clutch at the end takeoff 10 is engaged. at time t2, the generation of a ramp function by the module 15 of FIG. 2, described above, makes it possible to obtain a reference of the rotational speed of the motor wtgt converging towards the rotation speed of the primary shaft 5 wp up to the rotation speed w3. From time t3, the clutch is closed, the rotational speeds of the primary shaft wp and the output shaft of the motor w are synchronized while avoiding the generation of shocks. This defines an optimum trajectory for the engine speed following that of the primary speed wp, while operating the engine at its maximum torque. The engine speed is slaved closed loop to this trajectory, using the engine torque Cmot as control variable. FIG. 4 illustrates the evolution of the input clutch torque setpoint Cembtgt and the measured input clutch torque Cemb during take-off. On the ordinate, we find pairs expressed in N • m, and on the abscissa the time t expressed in seconds. The dashed line curve represents the driver's demand for torque to the CHTA wheels, the solid line curve to the Cembtgt input clutch torque setpoint, and the dashed line represents the actual input clutch torque. (measured) Cemb 20 At time to and until time tl, the acceleration pedal is not actuated. The CHTA, Cembtgt and Cemb pairs are void. From time tl, the driver depresses the accelerator pedal with a value P which corresponds to a request for equivalent torque to the CHTAp wheels. The input clutch torque setpoint Cembtgt, filtered from CHTA by the low-pass filter 12 of FIG. 2, begins to increase, then reaches the value CHTAp. It then remains constant until the time t4 when the clutch is completely closed. The measured input clutch torque Cemb, driven in a closed loop by the regulator 5 on page 1, also starts to increase, then reaches the value CHTAp and remains constant until the time t4. An optimum trajectory is thus defined for the clutch torque Cemb, which makes it possible to avoid jolts during closing of the clutch. In summary, thanks to the system and the method for controlling the so-called "take-off" phase of the vehicle that has just been described, the take-off of the vehicle 7 is dependent on the variations of support P on the acceleration pedal, vehicle V speed 7 and CHTA wheel torque demand. Moreover, this control system and method allows the vehicle 7 to reach a target speed as quickly as possible, while ensuring saturation of the rotational speed of the engine w by the rotational speed of the primary shaft wp, with the aid of the security module 9, as well as an elimination of shocks during closing of the input clutch, with the closing clutch of the input clutch at the end of take-off 10 and of generating a smoothed Cemb entry clutch torque.

Claims (10)

REVENDICATIONS1. Control system for a movement phase, when a driver is acting on an accelerator pedal, of a vehicle equipped with a motor transmitting a torque to a gearbox, via at least one input clutch controlled by a control sequence for coupling or decoupling progressively in rotation a primary shaft with an output shaft of the engine, characterized in that it comprises a module (1) for generating a a motor rotation speed setpoint (wtgt), a motor torque setpoint (Cmoffgt), and an input clutch torque setpoint (Cembtgt) from the vehicle speed (V) (7), the position (P) of the accelerator pedal and the request of torque to the wheels (CHTA), these three setpoints being used to control the rotation speed of the engine (w) and the clutch torque of entry (Cemb). 2. Control system according to claim 1, characterized in that it comprises a device (4) for regulating the speed of rotation of the motor (w) around the set point (wtgt), and a regulating device (5) for input clutch torque (Cemb) around the setpoint (Cembtgt) • 3. Control system according to claim 1 or 2, comprising an open loop for calculating the setpoint of the input clutch torque (Cembtgt), an open loop for calculating the motor torque setpoint (Cmottgt), and a motor closed loop which is controlled from the sum of the motor torque setpoint (Cmottgt) and an adjustment torque (CPI)). 4. Control system according to claim 1, 2 or 3, wherein the module (1) for generating the setpoints comprises a module (8) for generating a nominal value of rotational speed of the engine filtered (wtgtF), a safety module (9), a closing module (10) for the clutch at the end of take-off, a module (11) for generating the engine torque setpoint (Cmoffgt) and a module (12). ) of the input clutch torque setpoint (Cembtgt) • 5. The control system as claimed in claim 4, wherein the module (8) for generating a filtered engine rotation speed reference value (wtgtF) comprises a map C receiving as input setpoint values as a function of the speed (V) of the vehicle (7) and the position (P) of the accelerator pedal. 6. Control system according to claim 4 or 5, wherein the module 10 (10) for closing the input clutch at the end of takeoff comprises a means (13) for comparing the difference of the rotational speeds of the shafts. motor and primary (wtgtF - wp) with a threshold (5) and means (15) for generating a ramp setpoint so as to replace the engine rotational speed reference value with a ramp function. 15 7. A method of controlling a movement phase, during the action of a driver on an accelerator pedal, of a vehicle equipped with a motor transmitting torque to a gearbox, by means of intermediate of at least one input clutch controlled by a control system for progressively coupling or decoupling in rotation a primary shaft with an output shaft of the engine, characterized in that: - a speed setpoint is developed of rotation of the motor (wtgt) and a setpoint of motor torque (Cmoffgt) from the speed (V) of the vehicle (7) and the position (P) of the accelerator pedal, - a torque setpoint is developed Starting clutch (Cembtgt) from the request of torque to the wheels (CHTA), - the torque applied to the engine is regulated in closed loop, from the engine torque setpoint (Cmottgt) and a adjustment torque (Cp = p) capable of canceling the error between the rotat speed set point the rotational speed of the engine (wtgt) and the measured value 2957645 -15- of the rotational speed of the engine (w). 8. Control method according to claim 7, wherein a set value of rotational speed of the filtered motor (wt9tF) is defined by a map (C) and is modified by switching on a security module (9) and a module (10) for closing the input clutch at the end of take-off in order to obtain the engine rotation speed reference (wt9t). 9. The control method according to claim 8, wherein the value of the rotational speed of the primary shaft (wp) is compared with the setpoint of the rotational speed of the filtered motor (wt9tF). 10 10. A control method according to claim 8 or 9, wherein a module (10) for closing the input clutch at the end of take-off is engaged when the difference in rotation speeds of the motor and of the primary shaft ( wt9tF -wp) is less than or equal to a threshold (5), and a ramp setpoint is generated for the engine rotation speed, so as to replace the filtered engine rotation speed reference (wt9tF) by a ramp function , and to converge the rotational speed of the engine on the rotational speed of the primary shaft (wp).