WO2008151922A1

WO2008151922A1 - Method and device for controlling a clutch

Info

Publication number: WO2008151922A1
Application number: PCT/EP2008/056455
Authority: WO
Inventors: Rainer Petzold; Anthony Robert Sayman; Ludger Ronge
Original assignee: Zf Friedrichshafen Ag
Priority date: 2007-06-15
Filing date: 2008-05-27
Publication date: 2008-12-18
Also published as: DE102007027702A1

Abstract

The invention relates to a method for controlling a clutch, particularly a friction clutch in a power train of a motor vehicle, by way of which an internal combustion engine can be connected to a transmission, wherein clutch waypoints are determined by means of at least one training process. In order to enable comfortable and safe starting processes with constant starting conditions, at least one marginal clutch waypoint determined by means of monitoring engine relevant parameters is activated in a stationary vehicle having the first gear engaged, based on a previously determined stationary point of the clutch without torque transmission, while the clutch moves in the locking direction. In a device for carrying out the method, a control unit comprises means for detecting and processing engine-, clutch- and transmission-relevant data and clutch waypoints derived therefrom for storing the data.

Description

Method and device for controlling a clutch

The invention relates to a method for controlling a clutch according to the preamble of patent claim 1 and to an apparatus for carrying out the method according to the preamble of patent claim 12.

In vehicles with automated manual transmissions or automatic transmissions with an automatic friction clutch as drivable starting element to control the torque transmission between the drive motor and the transmission of an electronic control device various operationally relevant sensor data, such as engine speed, transmission input speed, accelerator pedal position, driving speed and switching intent supplied and after a corresponding evaluation Disconnecting or engaging the starting clutch, possibly with a variable closing or opening, triggered.

In order to ensure a flawless and comfortable driving, it is known in automatic clutches to determine the individual path conditions in the adjustment of the friction partners, in particular characteristic Kupplungswegpunkte, such as the Zupunkt or application point, via automatic Einlernprozesse. This results in a coordinate system over which certain functions of the clutch, for example, "clutch open when switching" or "waiting position when the vehicle is stationary with gear engaged to start request signal is generated", can be displayed.

Since the travel conditions for the closing and opening of the clutch and thus also the torque transmission of the clutch over its life, in particular by wear, and in the current operation by external influences, such as different temperatures and speed fluctuations, may change, it is necessary, the Einlernprozesse preferably at each clutch actuation or at least at predetermined intervals perform to adjust the relevant Kupplungswegpunkte corresponding to the current path conditions for the clutch operation.

Various methods for teaching characteristic clutch waypoints are known from the prior art:

For example, DE 103 52 61 1 A1 proposes a method for adapting a clutch travel point which is defined as a grinding point with starting engagement, in which a teaching of the waypoint is not carried out with a clutch moving in the closing direction but with the clutch being opened by detecting a clutch Differential speed between the drive side and output side of the clutch takes place. In addition, in order to take into account a hysteresis of the clutch travel, a second waypoint can be determined when the clutch is closing.

DE 100 54 867 A1 describes a method for adapting a clutch travel point defined as a creep point for setting a desired creep torque. The actual transmission torque of the clutch is compared with a transmission torque of a creep point set in a preceding cycle, and in the event of a deviation from a desired creep torque when the starting gear is engaged, a reference point between a grinding point and the creep point is assumed, via which a new creep point is determined. which corresponds to the desired creep torque.

DE 695 16 391 T2 describes a method for determining a clutch point defined as a contact point, in which the clutch moves at a constant speed in the closing direction and from a detected at a time interval speed difference of a transmission input shaft two positions of the closing path is closed to a lying before the first position touch point.

DE 101 63 438 A1 proposes a method for determining a coupling application point, which is defined as the limit point of a torque transmission which starts when the clutch is engaged further. The procedure can also be carried out with the engine off. Therein, in contrast to the conventional use of speed and motor signals, a manipulated variable is varied. In particular, the application point is detected on a discontinuity in a gradient of a disengaging force or on a value of zero accepting contact force of the clutch.

DE 103 06 934 A1 shows another method for determining a contact point with incipient torque transmission without the inclusion of engine-related sensor data, in which an unsynchronized reverse gear is used. In this case, a contact point is determined when the vehicle and the engine is running when the torque transmission of the clutch is sufficient to move the teeth of a sliding sleeve against the teeth of a coupling body of a reverse gear in a tooth-on-tooth position.

Disadvantageously, in the known methods and the taught coordinate systems changes of the relevant Kupplungswegverhältnisse of a startup to the next startup in befindendem with gear engaged vehicle have been considered rather insufficient. However, in particular in the area of torque transfer, that is to say in the transition between open and slipping clutch, temperature and speed fluctuations may cause comfort and safety problems when starting and / or maneuvering. For example, the startup clutch is disengaged when stopping the vehicle, triggered by the clutch control, by means of a clutch actuator, for example, to prevent the engine is strangled when the speed drops below an idle speed and / or to prevent the vehicle from cranking when the brake is not actuated , can be relatively large by a changing due to changing Kupplungswegpunkte too wide clutch closing path in the subsequent start-up until the start of torque transmission. This can lead to disturbing and wear-increasing torque surges and / or to an undesired short-term rolling of the vehicle against the selected approach direction.

If, on the other hand, the clutch is not disengaged when the vehicle is stationary and the gear is engaged, a comparatively high torque can be transmitted already at a standstill by a contact point that is too far in the direction of engagement of the clutch, resulting in an undesirably high creep tendency of the vehicle.

Against this background, the invention has for its object to provide a method for controlling a clutch, which provides as independent as possible from operational influences largely consistent comfortable starting conditions available and ensures high reliability. Furthermore, an apparatus for carrying out such a method is to be described.

The solution to this problem arises from the features of the independent method claim and the device claim, while advantageous embodiments and modifications of the invention are the dependent claims. The invention is based on the finding that when learning or adapting a clutch coordinate system starting from a first specific clutch travel point, in which the clutch is just safely opened under all operating conditions, a second clutch travel point, in which a very low torque is being transmitted, is approached can, which in each case a clutch position is determined in a limited adjustment range, which allows largely consistent initial conditions for the start-up and maneuvering.

Accordingly, the invention proceeds from a method for controlling a clutch, in particular a friction clutch in a drive train of a motor vehicle, via which an internal combustion engine can be connected to a transmission in which clutch travel points are determined with the aid of at least one learning process.

To achieve the object, the invention provides that, at least when the vehicle is engaged starting gear, starting from a predetermined rest point of the clutch without torque transmission, a, moving in the closing direction clutch with the help of monitoring engine-related parameters, determined, marginal Kupplungswegpunkt with low torque transmission is approached.

For carrying out such a method according to the invention, the invention also provides a device in which a control device for controlling the clutch has corresponding means for detecting and processing engine, clutch and transmission-relevant data and for storing clutch waypoints derived therefrom.

Since speed data and fuel injection quantity data are available anyway in modern motor vehicles, these data can be fed to an existing control device of the clutch and can be used by means of a suitable controller adapted evaluation or a suitable evaluation program are processed. The actuating device of the clutch is then acted upon in each case with the corresponding control signals. Thus, the method according to the invention can be implemented particularly cost-effectively in existing motor vehicles.

The inventive method is particularly advantageous for automated manual transmissions applicable. In principle, however, it can be used mutatis mutandis in all types of powertrains and transmissions with automatic clutches, for example, in dual-clutch transmissions, step machines and continuously variable automatic transmissions.

By the method is advantageously achieved that start-up and maneuvering operations can always be initiated with the same conditions and high comfort. In particular, torque shocks and switching delays are avoided by excessively long clutch travel in the torque transfer of the clutch or increased wear by undesirably high friction torque at standstill with too tight friction partners of the clutch and significantly reduces the risk of unwanted rolling against the selected approach direction.

This is achieved with a gear engaged vehicle by a stable and under all conditions very low torque transmission. For this purpose, a rest point is first determined in which the clutch is safely open under all circumstances, that transmits no torque. This rest point serves as a starting point for the coupling positioning as well as a reference point for the acquisition of engine-relevant data without torque transmission to the gearbox. As engine-relevant parameters, the idling speed and / or the idling fuel injection quantity and optionally also the engine torque of the internal combustion engine can be detected and evaluated. The determination of the rest point is advantageously carried out as a function of a previously taught when stationary vehicle driving point as auxiliary coordinate. The driving point can be taught by, when starting from completely open clutch in the closing direction moving clutch, a speed monitoring a behebeeingangsseitigen secondary side of the clutch and when exceeding a predetermined speed threshold at the transmission input a clutch waypoint is determined and stored as a driving point.

When determining the rest point, a clutch disengagement or design-dictated minimum disengaging travel is advantageously taken into account. As a result, a rest point can be found in a simple manner from the taught driving point, in which on the one hand, the clutch is securely opened and the other hand is as close as possible to a touch point or Anlegepunkt.

For the following positioning of the clutch on a clutch waypoint with low torque transmission, the clutch is moved in the closing direction when the starting gear is engaged, starting from the open clutch position at rest. The incipient friction of the primary and secondary side friction partners of the clutch causes a decrease in the engine speed below the idling speed. This speed loss is compensated by readjusting the idle injection amount via an existing idle controller of the engine control, wherein in the transition region starting torque transmission, the increase of the injection quantity varies at least approximately proportional to the transmission torque of the clutch.

Since the idling control is relatively sensitive, a marginal clutch travel point, ie a waypoint close to the edge of the torque transmission, can be detected with a very low transmission torque and be adjusted. Additionally or alternatively, the idle speed can be used directly for the determination of the incipient torque transmission of the clutch.

The method is preferably carried out in each case with vehicle inlaid with starting gear - without starting request. Thus, this setting reproducibly created the same starting conditions for the respective approach of the driver.

In principle, the rest point can not only be used in the case of a vehicle already in gear as the starting position for setting the waypoint with low torque transmission for the subsequent starting process. Even when switching the starting gear itself, the rest point can be approached advantageous.

In order not to produce unnecessary wear, fuel consumption, and pollutant emission increasing friction work when the vehicle, can also be provided that when the starting gear with brake on a service brake or a parking brake when exceeding a predetermined time threshold or at the expiration of a predetermined period of rest is approached and only at a detected reduction of braking energy of the clutch travel point is approached with low torque transmission.

Furthermore, it can be provided to reduce the friction work and thus to reduce the wear of the clutch that when in-gear without braking operation standing vehicle and already approached Kupplungswegpunkt with low torque transmission when exceeding a predetermined period for starting the vehicle, so if the driver despite the brake released and starting low torque transmission within a certain period does not start, first again the Rest point is approached by a corresponding clutch adjustment. In principle, it is possible that, when the rest point is reached in a cyclical sequence, the waypoint is approached again with little torque transmission in order to ensure a short actuation time and a high starting comfort in the eventual subsequent start-up procedure.

To increase the ride comfort in automated manual transmissions can further be provided that in a switching operation while driving the clutch is opened and then the previously learned when engaged with starting gear vehicle and stored Kupplungswegpunkt is approached with low torque transmission.

Conveniently, additional waypoints may be determined to complete the clutch path coordinate system. In particular, a point in which the clutch is fully engaged, via a movement of the clutch in the closing direction until reaching an end position, ie the position at which the path gradient of the clutch assumes the value zero during the closing process, are taught. In addition to the rest point, a pre-selectable application point, at which the friction partners of the clutch touch, can be determined via the previously learned driving point.

To clarify the invention, the description is accompanied by a drawing of an embodiment. Therein, the single FIGURE shows a flow chart for the sequence of a method according to the invention for controlling an automatic friction clutch in a drive train of a vehicle.

Accordingly, when the vehicle is stationary and the engine is idling, first a point of engagement and a driving point of the clutch are taught. In order to teach in the point of engagement, the optionally already closed clutch is actuated in the closing direction and checked for a path change equal to zero or, if appropriate, completely adjusted. disengaged. To learn the driving point, the clutch is fully opened and adjusted until the detection of a speed increase at the transmission input in the closing direction. If a predefined speed threshold is exceeded, the current clutch position is defined as the pickup point.

From this driving point as an auxiliary position, a rest point is approached, which takes into account at least one structurally predetermined minimum disengaging path, so that the clutch is safely opened independently of external influences.

The clutch then moves in the closing direction when the starting gear is engaged. The insertion of the starting gear takes place after initiation by the driver, for example by pressing a switch from the neutral to a forward driving position. At this time, the idle fuel injection amount and / or the idling speed are observed. When determining an increased by the idle controller of the engine fuel injection quantity to compensate for the loss of speed at the engine due to the onset of friction Reibpartner the clutch, a Kupplungswegpunkt is detected at very low torque transmission and held the clutch on this target point as the starting point for an expected starting.

When initiating the starting process is signaled by the driver's approach, ie the operation of the accelerator pedal, the Zupunkt started, the clutch is fully engaged, whereupon the vehicle is in accordance with the engaged gear or the engaged gear in motion.

In addition, it is advantageous to provide service life monitoring in the case of a vehicle with a starting gear engaged. In this case, when exceeding a predetermined time threshold or at the expiration of a predetermined time room again approached the rest point and a waiting loop switched until it is interrupted by a release signal or at the latest by the start-up request. When the brake is applied, the release signal may be, for example, a drop in the braking energy, that is, a release of the brake pedal or the parking brake. Without brake actuation, the clutch can be set to the rest point after a monitoring timeout to a start-up request signal.

The teach-in cycle according to the invention is preferably carried out again before each start-up procedure, so that a stable, very low torque transmission of the clutch is achieved when the vehicle is in gear, regardless of parameters such as wear state, temperature or speed fluctuations. Thus, start-up and maneuvering operations can be initiated with always the same conditions and high comfort.

Claims

claims

A method for controlling a clutch, in particular a friction clutch in a drive train of a motor vehicle, by means of which an internal combustion engine can be connected to a transmission in which clutch travel points are determined with the aid of at least one learning process, thereby indicating that at least at inlaid starting gear stationary vehicle, starting from a pre-determined rest point of the clutch without torque transmission, a, in the closing direction moving clutch with the aid of monitoring engine-related parameters determined, marginal Kupplungswegpunkt is approached with low torque transmission.

2. The method of claim 1, characterized Porsche Style n zei ch net, that the idle speed and / or the idle fuel injection quantity and / or the engine torque of the internal combustion engine are detected and evaluated as engine-relevant parameters.

3. The method according to claim 1 or 2, characterized Porsche Style nzeichnet that the rest point is determined in dependence on a previously learned driving point.

4. The method according to claim 3, characterized Porsche Style zei ch net that for learning the driving point, starting from the clutch in the closing direction moving clutch, a speed monitoring a transmission input secondary side of the clutch and when exceeding a predetermined speed threshold at the transmission input, a clutch waypoint as Carrying point is determined and stored.

5. The method according to at least one of claims 1 to 4, characterized Porsche Style zei ch net that a predetermined Mindestauskuppelweg is taken into account in the determination of the rest point.

6. The method according to at least one of claims 1 to 5, characterized Porsche Style n zei ch net that at rest with a starting gear with braking operation vehicle is approached when exceeding a predetermined time threshold, and at a detected drop in braking energy of the clutch waypoint with low torque transmission is approached.

7. The method according to at least one of claims 1 to 6, characterized Porsche Style n zei ch net that at rest with a gear engaged without braking and the vehicle already approached Kupplungswegpunkt with low torque transmission when exceeding a predetermined period for starting the vehicle again the rest point is approached ,

8. The method according to at least one of claims 1 to 7, characterized Porsche Style n zei ch net that when switching a starting gear when the vehicle is stationary, the rest point is approached.

9. The method according to at least one of claims 1 to 8, characterized Porsche Style n zei ch net that the clutch is opened while driving the clutch and then the previously learned when engaged with starting gear vehicle and stored Kupplungswegpunkt is approached with low torque transmission.

10. The method according to at least one of claims 1 to 9, characterized Porsche Style zei ch net, that a Zuppunkt, in which the clutch is fully engaged, via a movement of the clutch in the closing direction until reaching an end position at which the path change of the clutch during the closing process assumes the value zero, is taught.

11. The method according to at least one of claims 1 to 10, characterized Porsche Style n zei ch net, that a preselectable application point, in which touch the friction partners of the clutch, is determined in dependence on the previously learned driving point.

12. An apparatus for controlling a clutch, in particular a friction clutch in a drive train of a motor vehicle, via which an internal combustion engine with a transmission is connected, characterized Porsche Style n Zeich n et that a control device for controlling the clutch means for detecting and processing engine, clutch Has - and control-relevant data and for storing derived therefrom Kupplungswegpunkte, by means of a method according to one of claims 1 to 11 is feasible.