FR3003321A1 - METHOD FOR CONTROLLING A FRICTION-CLUTCH CLUTCH SYSTEM - Google Patents

Abstract

A method of controlling a clutch system with friction members for a power train comprising a motor, an automated gearbox and said clutch system interposed between the engine and the gearbox, the clutch being able to occupy a closed position coupling, an open decoupling position and intermediate positions during coupling phases and during decoupling phases. At the control of passage of the clutch from its open position to its closed position, the method comprises a filtering (122, 124, 142) progressivity of a torque transmission setpoint (CembCns) by the clutch, when this setpoint becomes positive at the passage of a licking point of the clutch to which the friction bodies begin to slip. A control system vehicle (10) configured to implement said method.

Description

The present invention relates to a method of controlling a clutch system with friction members. More particularly, the invention relates to a control method of a friction clutch system for a powertrain comprising a motor, an automated gearbox and said clutch system interposed between the engine and the gearbox, the clutch being able to occupy a closed coupling position, an open decoupling position and intermediate positions during coupling phases and during decoupling phases. This kind of process is known from FR2933462. This document discusses slip commands and constraints on actuators. In addition to the clutch closing speed, there are issues relating to the management of the clutch for rapid and / or sudden crossing of a point of licking of the friction members. It must be avoided that the passage of the point of licking generates a shock that could be felt by the driver and passengers of the vehicle. This shock would be all the more important that the couple would be fast. The present invention is intended in particular to improve the solutions of the prior art. For this purpose, the invention relates to a control method of a friction clutch system for a powertrain comprising a motor, an automated gearbox and said clutch system interposed between the engine and the gearbox, the clutch being able to occupy a closed coupling position, an open decoupling position and intermediate positions during coupling phases and during decoupling phases. At the control of passage of the clutch from its open position to its closed position, the method comprises a progressively filtering a torque transmission setpoint by the clutch, when this setpoint becomes positive at the passage of a point of licking the clutch to which the friction bodies begin to slide. In various embodiments of the method according to the invention, one can optionally also resort to one and / or the other of the following provisions: the filtering is monodirectional operating only to the control of passage of the clutch from its open position to its closed position; the filtering includes a parameter representative of the driver's will according to at least one acceleration recommendation; filtering comprises a function producing a gross torque setpoint clutch as a function of the parameter representative of the driver's will and a treatment of the raw setpoint by a filtering strategy of passage of the licking point, to determine a final clutch torque setpoint to be transmitted by the clutch; the filtering comprises a step of transforming the final torque setpoint into a displacement position set of the friction members; filtering uses accelerator pedal position data as a recommendation for acceleration; the filtering uses a value corresponding to a percentage of the difference between a value of an input dependent on the raw torque setpoint clutch at a current time and a final setpoint torque output at a time step previous; the time interval between the preceding time step and the current time is substantially ten milliseconds; the setpoint becomes positive at the passage of the licking point of the clutch being greater than zero and varying substantially up to three Newton meters. Furthermore, the invention also relates to a motor vehicle comprising a power train comprising a motor, an automated gearbox and a friction clutch system interposed between the engine and the box, the clutch which can occupy a closed coupling position, an open decoupling position and intermediate positions during coupling phases and during decoupling phases. The vehicle comprises a control system configured to implement the method according to the invention so that the sliding can be progressive at the passage of the licking point of the clutch. Other objects, features and advantages of the invention will become apparent from the following description of one of its embodiments, given by way of non-limiting example, with reference to the accompanying drawings in which: FIG. 1 illustrates the method according to the invention in connection with a vehicle control system; - Figure 2 is an operating chronograph illustrating an application of the method according to the invention showing clutch torque instructions over time; FIG. 3 is a principle chronograph of filtering according to the method according to the invention; FIG. 4 is a chronograph of the filtering of FIG. 3 for a value used in the method according to the invention; FIG. 5 is a chronograph of the filtering of FIG. 3 for another value used in the method according to the invention. The invention applies to a motor vehicle provided with a powertrain comprising a motor, an automated gearbox and an automated clutch system, this system having friction members interposed between the engine and the box. Conventionally, the clutch is interposed between on the one hand the flywheel associated with the crankshaft of the engine and on the other hand the primary shaft of the gearbox, this shaft being conventionally geared gear gears gear ratios of the gearbox. gearbox. The clutch can occupy a closed coupling position, an open decoupling position and intermediate positions during coupling phases and during decoupling phases. In the intermediate positions, a licking point corresponds to the position of the clutch from which there is friction between two discs of friction members of the clutch and thus a beginning of passage of torque when the clutch passes from its open position to its closed position. [0012] Robotic transmission systems, or automated manual transmission systems, constitute an intermediate solution between conventional manual transmissions and automatic transmissions. Unlike the latter, characterized by complex mechanical components such as torque converters and planetary gear trains, the robotics transmissions use a clutch and a gearbox that have a traditional mechanics but are controlled, not by the driver but by a control system. In the case of a robotic transmission, the vehicle does not include a clutch pedal, and it is the control system that measures the action of the clutch in coordination with the production of engine torque. This control system coordinates the smooth running of the vehicle mobility by the powertrain group. The control system may comprise computers, also called electronic control unit, which may be different for the operation of the engine and for the operation of the gearbox with the associated clutch. The control system must generate instructions for: servocontrol of the position of the friction members of the clutch associated with a clutch actuator; the servocontrol of interconnection actuators associated with the gears of the gearbox; the engine control which determines the torque produced by the engine essentially according to an acceleration recommendation which is for example a parameter representative of the position of the accelerator pedal. In the case of the movement of the vehicle from the stop, this setting in motion being commonly called "take-off", the progressive closing of the clutch, and its coordination with the production of the engine torque, is a key phase control of the robotic transmission. During take-off, the smooth crossing of the licking point is crucial for the quality of the service perceived by the occupants of the vehicle. In the embodiment considered as an example, the control system 10 comprises a supervisor 12 in which are implemented certain control method steps and a close control unit 14 which implements other steps of control method. In FIG. 1, the control system 10, the supervisor 12 and the close control unit 14 are symbolized by mixed dotted lines surrounding process steps considered in solid lines. The close control unit 14 is considered to be part of the automated clutch system. The invention relates to a method for controlling the closing phase of the clutch in the so-called automated robotic transmission system. In an operating hypothesis to be avoided, the rapid and / or sudden crossing of the licking point would cause a shock felt by the driver and the passengers of the vehicle. This shock would be all the more important that the couple would be fast. Thus, the method according to the invention introduces a filtering of the setpoint around the licking point of the clutch in order to control the torque gradient and thus to impose a torque setting profile so as not to generate shock. In addition, it is important not to delay a request for clutch opening. Indeed, in certain life situations such as anti-stall, it is necessary to open the clutch as quickly as possible so as not to transmit torque to the engine and thus allow it to not stall. For this purpose, the filtering is monodirectional so as not to delay the opening of the clutch and thus to avoid any excess torque on the end of the opening of the clutch. To understand the operation of the powertrain in a torque increase phase during which the friction members are sliding, for example at takeoff of the vehicle, it must be considered that the torque transmitted by the clutch, which corresponds to a fraction of the engine torque, is seen on the one hand as a negative torque crankshaft side, this transmitted torque thus avoiding the net torque provided by the engine, and on the other hand as a positive torque side transmission downstream of the clutch . It is this torque that, multiplied by the gear ratio engaged in the gearbox, is transmitted to the drive wheels of the vehicle. The state of the powertrain is then defined by variables measured upstream and downstream of the clutch. Typically, this is the upstream engine speed, always available on a vehicle, and a speed measurement downstream of the clutch such as the speed of the primary shaft, the speed of the secondary shaft or the wheel speed . During take-off of the vehicle, the movement of the vehicle is obtained by transmitting a larger and larger fraction of the engine torque to the primary shaft, and therefore to the wheels, through a gradual closing of the clutch. The clutch progressively and then gradually couples the flywheel to the primary shaft, thus transmitting the torque produced in the motor to the primary shaft. The torque tap is defined as the passage of the clutch from an open state corresponding to open positions to intermediate positions for a sliding friction state of the friction members. This therefore corresponds to an increase in torque around the licking point, ie a negative torque setpoint towards a positive torque setpoint. In the method for preventing shocks when crossing the licking point of the friction members of the clutch, a gross set torque CembRaw clutch is corrected in CembCns final torque clutch setpoint. The position of licking point corresponds to the position of the clutch from which there is friction between the two disks of friction members of the clutch and thus at the beginning of the passage of torque. At the point of licking, the friction members begin to transmit torque from the engine to the gearbox. The correction is, in an example of variation curves instructions, shown in principle in Figure 2. The ramping torque increase of the clutch torque is softened during the passage of licking points which are in correspondence of the null torque on the ordinate axis. In Figure 2, the CembRaw gross clutch torque setpoint curve is in solid continuous line and the final clutch torque setpoint curve CembCns is in strong dashed lines. For a step of the method, the supervisor 12 implements a first function 122 developing the raw set torque clutch CembRaw to meet the will of the driver. The first function uses various parameters, for example a 12P accelerator pedal position data and other parameters including, for example, the vehicle speed and / or the speed of variation of the positioning of the accelerator pedal. For another step of the method, the CembRaw raw setpoint is then processed by a passage filtering strategy 124 of the one-way licking point, to determine the final setpoint clutch torque CembCns. This final setpoint CembCns is then sent to the close computer 14 of the gearbox. The drive unit 14 close to the gearbox will then, by a transformation step 142, transform the final torque setpoint CembCns, the unit of which is the Newton meter (Nm), into a position setpoint. to move the friction members to their appropriate position by the appropriate actuators of conventional type. The unit 14 for close control of the gearbox indicates to the supervisor 12 for its filtering strategy 124 LimCemb the range of torque control by the clutch. This range comes for example from a map stored in a memory 14M. It varies from Cemb min to Cemb max depending on the use of the clutch. In the filtering strategy 124, there is a command for the clutch to be completely closed, in abutment position, when the instruction sent by the supervisor will be equal to Cemb max. In the filtering strategy 124, there is a command for the clutch to be open at its maximum, when the instruction sent by the supervisor will be equal to Cemb min. In the filtering strategy 124, there is a command for the licking point to correspond to a zero torque setpoint. This position corresponds to the position of the clutch from which there is friction between the two disks of the friction members of the clutch and thus at the beginning of the passage of torque. It is accepted that the beginning of the passage of torque may correspond to a torque greater than 3Nm. In the filtering strategy 124, the clutch is used to switch torque only when the torque setpoint is positive (> 0Nm). Conversely, it is considered that there will be no change in torque when the torque setpoint is negative. In fact, a raster torque of less than 3 Nm can remain. In the filtering strategy 124, the filtering principle is as follows: S (z) = Min (S (z1) + X * (E (z) -S (z-1)), E (z) In this function of calculation and choice of minimum instruction to determine the final setpoint CembCns at a current instant (t) by the mathematical operator Min, are taken into account the raw setpoint parameters CembRaw at the current time. (t) and final setpoint CembCns at a past instant (t-nt). The explanations for the various calculation elements are as follows. E (z) = CembRaw (t) S (z) = CembCns (t) S (z1) = CembCns (t-At) (E (z) -S (z-1)) = 1 (z) At represents the value of the discretization time of the system. For example, this time value is the interval equal to ten milliseconds (31 = 10ms). More generally, this time interval 31 can be between 1ms to 20ms for a control variable of the clutch X is a value corresponding to a percentage of the difference between the value of the output at the previous time step and the input 1 (z). In the calculation function of the filtering strategy 124, the value X * 1 (z) is added to the output of the previous time step. The value X varies from 0 to 1. When X = 0, the output remains fixed. When X = 1, the output is equal to the input so filtering is disabled. The value X depends: a variable representative of the will of the driver, for example the depression of the accelerator pedal, torque setpoint from the driver's will by actuating for example a cruise control of the vehicle; the difference between the value of the clutch setpoint S (z-1) and the position of the licking point. The position of the licking point is a calibration or value learned dynamically (in Nm) to take a reference for filtering. In the case of a calibration, this value is generally associated with ONm or is very slightly positive. It is slightly positive, corresponding for example to a torque of less than 3Nm. Thus, the torque transmission setpoint becomes positive at the passage of the licking point of the clutch being greater than zero and varying substantially up to three Newton meters. Two Newton meters or four Newton meters may be considered equivalent quantities. Monodirectional filtering is provided by the mathematical operator Min, but also by the value of X = 1 when E (z) <S (z-1) -P. In this last calculation, P is the position of the licking point. Figure 3 schematizes the filtering principle illustrating an application of the method to avoid shocks when crossing the licking point of the clutch. The raw setpoint CembRaw (t) and the final setpoint CembCns (t) are represented at the intant (t). The instant (t-31) corresponds to a moment of a previous step of time. The raw setpoint CembRaw (t-31) and the final setpoint CembCns (t-31) are represented to the infant (t-nt) the time interval At being for example 10ms and being more generally between 1ms and 20ms according to the desired reactivity of driving the clutch. The vertical offset of the crosses at the moment (t) represents the torque attenuation, dependent on the value X, to avoid an impact when the clutch is at an intermediate position in correspondence of the point of licking. It is recalled that 1 (z) = (E (z) -S (z-1)), 1 (z) being indicated on the chronograph. Knowing that the value X may vary according to the instant (t) considered, the magnitude of the product X * I (z) can vary to vary the desired attenuation of torque increase slope. FIG. 4 schematizes the result of the filtering when X is at the zero value. At time (t), the final setpoint CembCns (t) is equal to the final setpoint CembCns (t-31) which was determined at the instant (t-31). FIG. 5 schematizes the result of the filtering when X is at the value 1. At the instant (t), the final setpoint CembCns (t) is equal to the raw setpoint CembRaw (t) at the same instant. Advantageously, the proposed filtering solution allows a clean control solution to avoid shocks and jolts during the torque increase phases without causing loss of reactivity when opening the clutch. Thus, the sliding is progressive at the passage of the licking point of the clutch.

Claims (10)

REVENDICATIONS1. A method of controlling a clutch system with friction members for a power train comprising a motor, an automated gearbox and said clutch system interposed between the engine and the gearbox, the clutch being able to occupy a closed position a coupling position, an open decoupling position and intermediate positions during coupling phases and during decoupling phases, characterized in that Cilie, the control of passage of the clutch from its open position to its closed position, the method comprises a filtering (122, 124, 142) progressivity of a torque transmission setpoint (CembCns) by the clutch, when this setpoint becomes positive at the passage of a licking point of the clutch to which the bodies of friction begins to slip. 2. Method according to the preceding claim, characterized in that the filtering (122, 124) is monodirectional operating solely to control the passage of the clutch from its open position to its closed position. 3. Method according to any one of the preceding claims, characterized in that the filtering (122, 124, 142) comprises a parameter (12P) representative of the driver's will according to at least one acceleration recommendation. 4. Method according to the preceding claim, characterized in that the filtering comprises a function (122) developing a raw torque clutch setpoint (CembRaw) according to the parameter representative of the driver's will and a treatment of the raw setpoint (CembRaw) by a strategy (124) for filtering the passage of the licking point, to determine a final clutch torque setpoint (CembCns) to be transmitted by the clutch. 5. Method according to the preceding claim, characterized in that the filtering (122, 124, 142) comprises a step of converting (142) the final torque setpoint (CembCns) position set to displacement of the friction members. 6. Method according to any one of claims 3 to 5, characterized in that the filtering uses a data (12P) of accelerator pedal position as an acceleration recommendation. 7. Method according to any one of claims 4 to 6, characterized in that the filtering (122, 124, 142) uses a value (X) corresponding to a percentage of the difference between a value of an input dependent on the gross clutch torque setpoint (CembRaw) at a current time (t) and a final torque setpoint output (CembCns) at a previous time step (t-31). 8. Method according to the preceding claim, characterized in that the time interval between previous time step (t-nt) and the current time (t) is substantially ten milliseconds. 9. Method according to any one of the preceding claims, characterized in that the setpoint (CembCns) becomes positive at the passage of the licking point of the clutch being greater than zero and varying substantially up to three Newton meters. 10. Motor vehicle comprising a powertrain comprising a motor, an automated gearbox and a friction clutch system interposed between the engine and the gearbox, the clutch can occupy a closed coupling position, a position open decoupling and intermediate positions during coupling phases and during decoupling phases, characterized in that the vehicle comprises a control system (10) configured to implement the method according to any one of the preceding claims so that the sliding can be progressive at the passage of the licking point of the clutch.