DE102005029566A1 - Method for protection of automatically actuated clutch of vehicle from overload, involves preventing overload state of clutch through targeted intervention in vehicle management as function of driving situation and energy input in clutch - Google Patents

Abstract

A driving situation such as creeping, starting off and driving of the vehicle, is determined, after which energy input in the clutch is determined , continuously. An overload state of clutch is prevented or reduced through targeted intervention in vehicle management as a function of determined driving situation and energy input in the clutch.

Description

The The present invention relates to a method for protecting an automated actuated Clutch of a vehicle against overload according to the preamble of claim 1.

such automatically operated Couplings can on vehicles equipped with different transmissions Find. The distinction of the transmission does not only apply the degree of automation, but also the design, so it For example, the transmission is an automated manual transmission, an uninterruptible gearbox, a parallel gearbox or a transmission with stepless change of the ratio can act. In such transmissions, the clutch exercises in the form the friction clutch in general two functions, namely once the function to act as a starting element and also the function to act as a switching element.

Either when starting as well as when restoring the traction connection between the engine and the driveline after a gear change operation will over the clutch a clutch torque at differential speed between the input and the output side of the friction clutch transmitted. It becomes inevitable Frictional loss as product of clutch torque and differential angular velocity in the clutch friction surfaces registered, leading to an increase in the temperature of the friction surfaces and so that the clutch leads overall.

Of the Wear the clutch friction depends on from the amount of energy input and the temperature. Next a normal wear of the friction surfaces can it also to secondary effects in the form of mechanical deformations of the friction surfaces and changes the friction coefficient of the friction surfaces come, so it for example at a drop in the coefficient of friction the friction partner to an extension the slippage phase can come and thus in turn to an increase of enlisted energy.

It is therefore of particular importance in dry-running clutches Meaning, the energy input into the clutch does not become too high allow.

at Vehicles with automated actuation Clutches is the direct operation the clutch deprived of the influence of the driver, but very well can the driver over his driving style on the wear behavior of the clutch influence to take.

So is it possible, for example, that a creep noticed or even unnoticed by the driver the vehicle against a slope or a delayed start-up on a Climb to an elevated Energy input leads into the coupling. Also leads a holding of the vehicle on a slope through the accelerator pedal to an increased Energy input into the coupling, which also applies, for example, in the case that the driver overlooks a tightened parking brake when starting.

Next This caused by the driver of the vehicle causes for a increased Energy input into the clutch can also be caused by errors in the System for actuation the automated friction clutch to an increased energy input come, such as due to a detuning of the hydraulic Track for clutch actuation, such as a leak. All these are just examples of causes for an increased Strain in the form of an increased Energy input into the friction clutch.

outgoing It is now an object of the present invention to provide a method to protect an automated actuated clutch of a vehicle against overload to accomplish.

The Invention points to the solution this object to the features specified in claim 1. advantageous Embodiments thereof are described in the further claims.

The invention now provides a solution to this problem, a method for protecting an automatically actuated clutch of a vehicle, wherein the driving situation of the vehicle is determined by the method, the energy registered in the clutch is detected continuously and in dependence on the fixed the selected driving situation and the en- ergy is avoided or reduced by a targeted intervention in the vehicle management of the overload condition.

Under The concept of determining the driving situation is used in the context of Present invention, the detection of the driving situation of the vehicle on the basis of existing or to be introduced Vehicle parameters and also the monitoring understood the driving situation to change, so that then depending of the detected entry of energy into the clutch a selection at intervention possibilities in the vehicle management to avoid or reduce the overload condition the coupling are performed can and the targeted intervention is then performed.

So is it possible, for example, as part of the detection of the driving situation of the vehicle a classification the driving situation and monitoring the determined driving situation.

In In this context, it is provided according to the invention, for example, to determine the driving situation between at least the situations Creeping, starting and driving to distinguish and this finding to carry out largely continuously or in predetermined Intermittent time intervals.

A size Meaning regarding the entry of power into the automatically actuated clutch will take slip states for a while Starting or a crawl, so it after a Further development of the method according to the invention is provided, in the driving situation starting between a startup when the vehicle is stationary and a starting process when not standing Vehicle to distinguish, here also the inserted gear is detected. For example, during a startup process met with a stationary vehicle another subdivision be with regard to the engaged gear, namely that Transmission in the first, in the second or another gear, such as in reverse, located. Even after a start on a slope a higher energy input in the friction clutch is expected, can also be based on existing Vehicle parameters, such as an evaluation of the throttle angle or the accelerator pedal position or, for example, a tilt sensor signal a detection of the driving situation of the vehicle can be performed.

It is provided according to the invention in this case that the energy introduced into the clutch is detected as the integral of the introduced at any time in the clutch friction over time according to the formula e friction = ∫P friction (T) dt, So that the energy input into the clutch is known at any time and in any driving situation.

The current friction is a product of the current slip speed n slip on the clutch and the current friction torque on the clutch MR, so that the friction results as P friction = M R ω slippage = M R 2πn slippage ,

The in the determination of the registered energy incoming friction torque can do so after a continuation of the invention are measured or by means of coupling characteristics be determined or also determined on the basis of existing parameters, such as the engine speed, the engine torque and the mass moment of inertia the engine and the clutch flywheel.

Thus, it is possible, for example, according to an embodiment of the method according to the invention, the friction torque according to the relationship M R = M Mot - J Mot ω. Mot = M Mot - J Mot 2πn. Mot . to ascertain, wherein the data required for determining the friction torque MR, namely the engine speed nMot, the engine torque MMot are transmitted via a bus system present in the vehicle, for example the CAN bus, and the mass moment of inertia of the engine and flywheel JMot is known.

After so the friction torque is known at any time, the in the Kupp registered energy at any given time.

To The invention now provides that in dependence predetermined threshold values of the energy introduced into the coupling or the expected energy input into the clutch different targeted interventions in the vehicle management are made, where the thresholds are predetermined or dependent can be determined from the current temperature of the clutch.

In order to can now in dependence the expected energy input depending on the determined driving situation or the energy actually recorded in the friction clutch different interventions in the vehicle management be made. It is possible to set the thresholds in dependence be predicted by the established driving situation or in dependence from the current temperature of the clutch to determine, so in determining the thresholds the current load situation the clutch can go with. Depending on the determined Energy entry thresholds can then made various interventions in the vehicle management become.

Provided For example, the determined or expected energy input in the clutch to a clutch temperature of, for example, up leads to 250 degrees Celsius, It can be assumed that the coupling has a normal load situation so that up to this associated energy entry threshold no Interventions in the vehicle management are carried out. With rising Temperature of the coupling become the tolerated energy entry thresholds, From then on, targeted intervention in vehicle management takes place be reduced.

If now based on the observed or expected energy input from a clutch temperature of about 250 degrees Celsius to about 350 degrees Celsius is assumed, so according to the invention comfort-restrictive interventions be carried out in the vehicle management, such as a Starting operation in second gear no longer perform.

If the detected or expected energy input to a clutch temperature of more than 350 degrees Celsius, for example, is another comfort-reducing Intervention in the vehicle management possible, such as a Reduction of engine torque output.

To a development of the invention, it is provided that the interventions in the vehicle management in dependence of predetermined thresholds an expected duration of a slip condition of the clutch of Vehicle executed can be. So it is also possible the expected energy input depending on the expected To determine the duration of the slip state of the clutch.

There the selection of targeted interventions in vehicle management as well dependent on the detected and supervised Driving situation of the vehicle to be carried out, it is after the Invention also provided that the respective intervention in dependence predetermined threshold values of the speed of the vehicle is executed, for any safety-critical interventions in vehicle management to avoid.

If according to the inventive method For example, it is determined that the vehicle is in the Driving situation creep is located on a slope, and the Evaluation of the vehicle speed shows that this almost Is zero and the energy entry threshold is exceeded, so that a clutch protective Intervention in the vehicle management becomes necessary, so can in this Situation the clutch will not be opened for safety reasons, what a rollback the vehicle would lead in the opposite direction, nor can the clutch be closed because the vehicle otherwise set in motion would, what the driver may wish does not correspond, so according to the invention, the interference in the Vehicle management look like that only an acoustic and / or visual and / or haptic indication to the driver of the vehicle is dispensed, so for example a visual warning in the display the vehicle appears, an audible warning about a Vehicle number is issued or a haptic warning to the Driver is issued in the form of an actively induced Fahrzeugruckelns by a corresponding operation the clutch.

According to a development of the invention, it is also provided that a predeterminable period of time is waited before the intervention in the vehicle management, during which the presence of the condition for the intervention is still checked. During this period of time, for example, a corresponding acoustic and / or optical and / or haptic warning message can be output to the driver of the vehicle, which signals that it is in the subsequent engagement in the driving management is not a malfunction, but a coupling protection function. If, during this warning time, the checking of the continued presence of the overload situation of the clutch shows that - for example due to a corresponding reaction of the driver of the vehicle to the warning information - the overload situation is no longer present, so according to the invention, the otherwise required intervention in the Vehicle management either no longer performed, or it follows an intervention in the vehicle management, which is a less comfort-reducing measure in terms of its weighting, such as a short-term prevention of starting the vehicle in second gear, but continue to start the vehicle in first gear with a lower energy input into the coupling is possible.

Depending on the energy input threshold, therefore, according to the invention, different interventions in the vehicle management in the form of measures to reduce the load on the clutch can be initiated. Examples of such measures depending on the detected driving situation are shown in the following table.

The Table shows only examples of targeted interventions in the vehicle management, so for example after recognizing the Driving situation "Creep against incline ", If this creep already exceeds a predetermined Energy entry threshold led has to be issued a warning to the driver, for example such that there is an optical indication that the coupling of the vehicle is overloaded becomes.

at the second example shown in the table "creep against incline with stationary vehicle "can be an effective intervention in the Vehicle management consist in that the creep function disabled is to avoid further thermal stress on the clutch the clutch is opened and at the same time a braking intervention takes place, the rolling back avoids the vehicle. This example shows that the targeted Intervention in the vehicle management also from a sequence of several Individual interventions can exist.

If it is determined in the context of determining the driving situation that the vehicle is in a crawl on a slope and while the vehicle speed is already greater than a walking speed, then a targeted intervention to avoid further thermal stress the clutch consist in that the clutch is completely closed.

If For example, according to the invention, it is determined that the vehicle on a slope over one activity the accelerator pedal or accelerator pedal of the vehicle is held, and the Energy entry threshold in the clutch a predeterminable threshold already exceeded has or exceeds threatens, then, for example, after a note to the driver, the clutch will be closed. The before closing the Clutch issued driver warning may possibly cause a change the behavior of the driver so lead that he the accelerator pedal not further pressed, so That the engine torque output decreases and thus the energy input in the coupling is reduced, so that a protection of the coupling by closing The clutch no longer needs to be implemented, as in the frame monitoring, whether the determined driving situation is still correct, determined was that this is no longer the case and now the situation "creep against incline "at standing vehicle has occurred and the above targeted interventions in the vehicle management are made.

If in the context of the method according to the invention for example, based on the evaluation of existing vehicle parameters it is determined that the vehicle is in a starting process located and for this purpose by the driver possibly the accelerator pedal is strongly penetrated to a corresponding high acceleration to reach the vehicle from a standstill, then this leads - already strong heated clutch - too an increased Energy input into the clutch, the driving situation-dependent energy input threshold is exceeded and the clutch is closed, which also without causing a safety-critical situation due to the evaluation of the accelerator pedal angle and the determination of the corresponding driver's request is possible.

If the determination of the driving situation provided according to the invention the vehicle a starting operation against the service and / or parking brake of the vehicle (stable), then this can be dependent further detected vehicle parameters to different targeted Intervene in the vehicle management lead, such as opening the Clutch, which is due to the already operated brake of the vehicle is not safety-critical, or even, for example, that the engine stopped by an intervention in the engine management become or strangled This is also in conjunction with a corresponding note can be done to the driver. Also, as a possible alternative to parking the engine only an intervention in the engine management in conjunction with a reduction in the drive torque delivered by the engine occur.

If according to the inventive method as part of the determination of the driving situation of the vehicle a "driving in progress " will and over In addition, an increase in the slip speed, then it can be closed be that the clutch slips due to faulty torque tracking and an intervention in the vehicle management in the form of an instruction the clutch control takes place to further close the clutch.

The The invention will now be explained in more detail below with reference to an example.

The energy input threshold depends on parameters such as the vehicle mass, the maximum available engine torque and other parameters such as the road gradient, the level of the starting speed and so on. If, by way of example only, a vehicle with a maximum engine torque of 200 Nm and a mass of 1,300 kg is considered, then in a full-load approach with a starting speed of about 2,000 l / min in the plane of an expected energy input of about 25 kJ be assumed, which may be more than 100 kJ in another driving situation, namely, for example, the start at full load and a slope of about 20%. As already mentioned above, energy input threshold values can also be determined as a function of the calculated or measured coupling temperature. If, in the above example, the approach of the vehicle in the plane at a clutch temperature of about 250 degrees Celsius an expected energy input of up to 60 kJ is determined, then a not yet critical load range of the clutch is determined by the inventive method, so that stress-reducing targeted interventions in vehicle management can still be avoided. This energy input threshold decreases with increasing detected or calculated clutch temperature, so that the energy input threshold at a clutch temperature of about up to 350 degrees Celsius drops to about 25 kJ, above which then targeted interventions are made in the management of the vehicle to reduce the load on the clutch , When the detected or calculated clutch temperature becomes greater than 350 degrees Celsius, the energy input threshold is further decreased and increased For example, a value of 15 kJ, at the crossing exceeded again targeted interventions are performed in the vehicle management, so for example, an intervention in the engine management to reduce the output torque provided or a closing of the clutch to end the slip condition.

The The invention therefore now provides a method to an automatically operated Clutch of a vehicle against overload to protect. On the basis of the determination of the driving situation, for example a crawl, a startup, a startup when pressed Service brake or parking brake of the vehicle, a drive of Vehicle or a switching operation are based on vehicle signals the respective driving situation and the respective energy input in the coupling corresponding targeted intervention in the vehicle management to avoid or reduce the state of stress of Coupling brought about.

Regarding not closer in detail Illustrated Incidentally, features of the invention expressly become apparent the requirements and the drawing referenced.

Claims (10)

Method for protecting an automatically actuated clutch a vehicle against overload, characterized by the following steps: - it will be the driving situation of the vehicle detected - it will be in the clutch registered energy continuously detected - dependent on of the detected driving situation and the enlisted energy The overload condition is achieved through targeted intervention in vehicle management avoided or reduced. Method according to claim 1, characterized in that that for determining the driving situation between at least the situations Creeping, starting and driving is distinguished and the finding is carried out largely continuously or intermittently. Method according to claim 1 or 2, characterized that in the driving situation starting between a startup when the vehicle is stationary and a starting process when not standing Vehicle is distinguished while the inserted gear determined becomes. Method according to one of the preceding claims, characterized in that the energy introduced into the clutch is detected as the integral of the introduced at any time in the clutch friction over time according to the formula e friction = ∫P friction (T) dt. Method according to one of the preceding claims, characterized characterized in that to determine the registered in the clutch Energy the friction torque is measured or based on clutch characteristics is determined or determined by the engine speed, the Motor torque and a mass moment of inertia. Method according to one of the preceding claims, characterized characterized in that depending predetermined threshold values of the energy introduced into the coupling or the expected energy input different targeted Interventions in vehicle management are made, with the thresholds are predetermined or dependent be determined by the current temperature of the clutch. Method according to one of the preceding claims, characterized characterized in that the intervention in the vehicle management in dependence predetermined thresholds of an expected duration of a slip condition the clutch of the vehicle to be executed. Method according to one of the preceding claims, characterized characterized in that the intervention in the vehicle management in dependence predetermined thresholds of the speed of the vehicle are executed. Method according to one of the preceding claims, characterized characterized in that before performing the engagement in the Vehicle management an optical and / or acoustic and / or haptic Signal is delivered. Method according to one of the preceding claims, characterized characterized in that before performing the engagement in the Vehicle management is waited for a predeterminable period of time, while the condition of the intervention is still checked.