DE102005033077A1 - Predicting overload in automatic clutch in motor vehicle during slip phase, by taking actions to avoid overload based on expected energy entering clutch and/or expected temperature - Google Patents

Abstract

The method involves determining the energy entering the clutch during a first period in the slip phase, and/or determining the current temperature of the clutch. The expected energy entering the clutch and/or the expected clutch temperature is determined based on the expected energy entering the clutch in a second period of the slip phase. Based on the expected energy and/or expected temperature, actions are taken to avoid overload.

Description

The The present invention relates to a method for predicting an overload an automatically operated Clutching a vehicle during a slip phase and to avoid the overload according to the preamble of claim 1. The invention also relates to a device to carry out the method according to the preamble of claim 11.

at a arranged in the drive train of a vehicle friction clutch is when starting and switching in the clutch friction power and Frictional energy introduced. The friction power leads to a temperature gradient in the clutch while the friction energy to an increase in the average clutch temperature leads.

at Such an automated clutch results in a predetermined position of the actuator in the form of, for example, an actuator actuated clutch transferable Clutch torque based on the clutch torque characteristic. Over a Adaptation of the clutch torque characteristic based on the clutch temperature or the friction energy introduced into the clutch can be caused by temperature change the transmission behavior be taken into account the clutch.

If the clutch but due to a short-term significant overload the risk of thermo-mechanical deformation of the clutch unit and the fading of the friction lining is exposed, then such critical situations to a significant change in the transmission behavior lead the clutch, the by an adaptation of the clutch torque characteristic no longer Account can be taken.

The Adaptation of the clutch torque characteristic already takes place on the basis completed changes the transmission behavior instead of the coupling and thus can be the danger of looming thermo-mechanical deformation of the clutch unit and the Danger of an incipient fading of the friction linings do not take into account.

outgoing It is the object of the present invention to provide a method for predicting an overload of an automated actuated Clutch of a vehicle to create and thus the possibility the early one Initiate remedial action to offer. It is also intended to provide a device for carrying out the method become.

The The present invention now provides a solution to this problem of the method, a method for predicting an overload an automatically operated Clutching a vehicle during a slip phase and to avoid the overload, wherein after the Procedures during a predetermined first period of the slip phase in the clutch registered energy is determined and / or the current temperature the clutch is detected and based on the expected second Duration of the slip phase of the expected energy input into the Clutch and / or the expected clutch temperature determined becomes and depending from the expected energy input and / or the expected Coupling temperature measures to avoid overloading be taken.

In order to The present invention provides a method by which the danger an overload such an automated actuated clutch is detected and then on the basis of the perceived danger of overloading timely action initiated, which avoid the detected overload. To this end It is provided according to the present invention that the slip phase the clutch, so the time during which the clutch in slip mode during a start-up procedure or a gear change operation of the transmission associated with the clutch, at least in two time periods is divided, wherein during the first predetermined Duration of the slip phase entered into the clutch energy amount is determined and based on the expected during the second Duration of the slip phase expected friction energy input in the Clutch measures to avoid an emerging overloading of the clutch become.

Since the measures to be taken here to avoid overloading the clutch in their valence can be tuned to the importance of the risk of overloading the clutch, it is after the invention provides that the measures to avoid overloading depending on the expected energy input and / or the expected coupling temperature can be selected. Thus, according to the invention, for example, more or less comfort-reducing measures to avoid overloading the clutch can be taken, in this context, as an example not as a driver comfortmindernd detected measure increasing the Überanpressung the clutch can be called and at a greater risk of overloading the clutch on the basis of a larger expected Reibendemenergietragtrags in the clutch a comfort-reducing measure can be taken by one hand, the clutch is closed faster and on the other hand, the motor torque output by means of an intervention in the engine control is reduced.

Next the selection of measures to avoid overloading the clutch depending on the expected energy input and / or the expected coupling temperature It is also provided according to the invention, these measures dependent on the first period of the slip phase and / or the expected second period of the slip phase to select. So, for example at a predetermined engine torque, a maximum allowable slip time determined, otherwise the friction energy input into the clutch exceeds a predetermined threshold. If now during a first slip period of the friction energy input into the clutch already the maximum permissible Friction energy input approaches, the slip speed, that is So the differential speed between the Kupplungseingangs- and the Coupling output side is still so great that the to dismantling the slip speed expected second duration of the slip phase, the duration of the slip phase already elapsed at the first time already elapsed is added, gets bigger as the maximum allowable Slip duration, then at the risk of overloading the clutch can be closed and it can take appropriate action to avoid overloading the clutch are taken, for example, the clutch to abbreviate the expected second Schlupfzeitdauer be closed faster.

There the duration of the slip phase also from the present in the drive train ratio and the vehicle speed depends this being essentially due to during a gear change operation present slip phase applies, it is according to a development the invention also provides the measures to avoid overloading the clutch in dependence the current gear of a transmission in the drive train of the vehicle and / or the speed of the vehicle.

As already mentioned above was, is when starting and switching in the clutch friction brought in. This friction power leads to a temperature gradient in the clutch. A high current friction can therefore be in short Time to a thermo-mechanical Deformation of the clutch unit and a negative change the coefficient of friction of the friction linings of the clutch lead, so that It is also provided according to the invention that the measures avoiding overload the clutch selected become dependent the current friction of the clutch and / or the gradient the current slip speed of the clutch. So go into the selection the measures to avoid overloading The coupling also comes at a very short term to bear monitoring parameters or selection parameters.

To The invention also makes a distinction with respect to the measures to be taken to avoid overloading the clutch in dependence the significance or the severity of the risk of overloading the clutch. If, for example, based on the during the second period of the slip phase expected energy input in the clutch is detected that during the entire slip phase in the clutch registered friction energy in the clutch too an expected clutch temperature of, for example, 140 degrees Celsius leads, and from experience it is known that a clear change the transmission behavior the clutch is used at a temperature of 140 degrees Celsius and this change the transmission behavior the clutch should be avoided, so after this finding the clutch can be closed faster to the duration of the friction energy input to decrease in the clutch. If on the basis of the expected Friction energy input during the expected second period of the slip phase is detected, that the unchanged Maintaining the slip condition during the second slip period to an expected clutch temperature of, for example, 250 degrees Celsius leads, then as a measure to avoid overloading the Clutch in addition to the faster closing of the clutch also an intervention in the engine control to reduce the engine delivered output torque can be performed.

In order to It is also provided according to the invention, the measures to avoid overloading the Coupling based on threshold values of the selection parameters or monitoring parameters perform.

To A development of the invention may also include areas between Thresholds are formed within which selectable actions to avoid overloading the clutch are classified such that depending the threshold ranges of the selection parameters the measures are selected. It can Thus, according to the present invention threshold ranges of Selection parameters or monitoring parameters be defined so that when the expected energy input values or, for example, slip duration values within a first one Threshold range, a first set of measures to avoid the overload the clutch selected which, for example, is detected less comfort-reducing by the driver becomes. But should the expected values be within another Threshold range would be an actual Reaching the higher Threshold ranges through the selection parameters or monitoring parameters a greater danger the overload of the Include coupling, so that according to the invention in this case then stronger comfort-reducing measures to avoid overloading the clutch are taken, such as a clear Reduction of the output torque from the engine.

To a development of the invention, it is also contemplated that the second duration of the slip phase based on the slip speed to be reduced is determined. It means in other words that it is during the the first period of the slip phase already to a reduction the slip speed of the clutch has come during the then known first period of the slip phase, so that on the Base of the present at the end of the first period of the hatching phase Slip speed the length the second period of the slip phase can be determined at whose end the slip speed has become largely zero, so So that largely equal speed exists between the engine output shaft and the transmission input shaft.

All In general, it is provided according to a development that means the measures to avoid overloading the clutch increases the gradient of reducing the slip speed, so that's action be taken, which covers the entire slip period of the clutch reduce the entry of the friction energy during the To reduce the slip time of the clutch.

To For this purpose, according to the present invention, the degree of Überanpressung the clutch increased be and / or the clutch will be closed and / or that of the engine torque to be transmitted to the clutch be reduced.

above were monitoring parameters or selection parameters called, based on their thresholds this Parameters can be determined on the basis of which, in turn, different measures to avoid the overload the clutch selected and performed can be. To The invention also provides that for the different Slip phases leading operations the startup and the gear change or the circuit separately different Threshold values of the selection parameters or monitoring parameters can be. For example, it is also possible different combinations of selection parameters or monitoring parameters to form the basis for the different measures to avoid overloading the clutch are taken.

When Example for this can be called that for each arrivals and circuits separated depending on the clutch temperature, the current gear and the current Vehicle speed and the introduced friction energy, the previous Duration of the slipping phase during the current startup process or the current switching process threshold values for the each defined selection parameters or monitoring parameters defined which are then grouped into threshold ranges within whose then selectable activities to avoid overloading the clutch can be selected.

The at the time of determining the current values of the selection parameters or monitoring parameters current friction power and the current gradient of the slip speed can now be evaluated so that the current friction and the current gradient to a selection of a preventive measure the overload the clutch leads, the more comfort-reducing measures include, for example a reduction in engine torque. This can one due to the current friction power or the current gradient of the slip speed higher Danger of overloading the automatically operated Clutch be taken into account.

Depending on the thus identified risk of overloading the clutch. can now be taken according to the invention, different measures to avoid the overload. That's the way it is, for example it is possible to close the clutch, ie to close it, whereby, depending on the threshold range, the clutch can be closed at different speeds, that is with different gradients of reduction of the slip speed. It is also possible, depending on the threshold values or the threshold ranges, to increase the overpressure on the clutch and to reduce the engine torque by means of an engine intervention, which can happen, for example, if it has been determined by the method according to the invention that the expected energy input, for example would lead to a fading of the friction linings of the clutch, so that even the fully closed clutch can no longer transmit the current engine torque.

The The invention now also provides a device for carrying out the Method, wherein the device has an actuator for actuating a Clutch in the drive train of a vehicle and a control device for controlling the actuator, wherein the control device for determining in the clutch during a slip phase enumerated frictional energy and to select from activities to avoid overloading the coupling is formed from a plurality of such measures, and activates the actuator according to the selected measures.

In order to The invention also provides a device with which depending from the danger of overloading the automatically operated Friction clutch different measures to avoid overloading be taken at a time before such an overload situation indeed can arise.

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

It is assumed that the situation of a startup of a vehicle with a trailer on a mountain. The approach is carried out under full load, so with fully actuated accelerator pedal. After a first period of the slip phase during the start-up process of 3 seconds, the current friction power is 9.5 kW, while the previously introduced friction energy is 37 kJ. Because of the slip speed still present after 3 seconds of the starting operation, it can now be determined that the expected second duration of the slip phase is a further 9 seconds, so that the total slip phase is approximately 12 seconds. During the second period of the slip phase, on the basis of this knowledge, an expected friction energy input as the integral of the friction power is determined to be 74 kJ. The current frictional loss results from the following relationship: Frictional power (Watt) = 2 · Pi / 60 · Slip speed (rpm) · Clutch torque (Nm), So from the product of the clutch torque and the slip speed.

There the thus predicted expected friction energy input on the basis the current clutch temperature to different expected Coupling temperatures leads, become the with the thus determined expected friction energy input expected temperatures are classified as critically different, as a result, different measures to avoid the overload the clutch are taken.

zeigt nun, dass anhand der aktuellen Kupplungstemperatur und der zu erwartenden Reibenergie unterschiedliche Schwellenwertbereiche (in diesem Fall der erwarteten Kupplungstemperatur) bestimmt werden, so dass dann, wenn die erwartete Kupplungstemperatur in Abhängigkeit vom erwarteten Reibenergieeintrag in unterschiedlichen Schwellenwertbereichen liegt, unterschiedliche Maßnahmen zum Vermeiden einer Überlastung der Kupplung ausgewählt werden.The following table

now shows that different threshold ranges (in this case the expected clutch temperature) are determined based on the current clutch temperature and the expected friction energy so that when the expected clutch temperature is in different threshold ranges depending on the expected friction energy input, different measures to avoid overloading the clutch can be selected.

If, for example, the current clutch temperature is less than 100 degrees Celsius, and the expected friction energy input reaches the value of 50 kJ, then this situation becomes "uncritical" stepped, so that no countermeasures are taken to avoid overloading the clutch, since this situation is not critical for the clutch. But if the current clutch temperature - for example due to already several such start-up operations - in the range of 200 - 300 degrees Celsius and the expected friction energy input again at 50 kJ, then this situation is classified as "critical 1", and it is the situation "critical 1 "To take appropriate measures to avoid overloading the clutch, for example, a much faster closing of the clutch to shorten the second period of the slip phase, so that due to the integral over time, the actual energy input into the clutch is much smaller than the expected friction energy input.

Lies now the current clutch temperature in the range of, for example 100-200 Degrees Celsius and is determined by an expected frictional energy input of 150 kJ, so leads This leads to an even more critical situation, which is "critical 2 "is designated and in addition to the action taken to avoid overloading coupling in the form of quicker tightening of the coupling still the engine torque is reduced. Accordingly, after the inventive method for predicting an overload the automatically operated Clutch also one as "critical 3 "rated situation ent, if indeed the current clutch temperature, for example, more than 200 degrees Celsius is and due to the expected friction energy input of 150 kJ at the present time Engine torque a much greater reduction in engine torque as a measure to avoid overloading the clutch is engaged.

If in the above-described starting situation of a vehicle with a trailer on a hill after starting, that is the onset of vehicle movement in the desired Direction, the slip speed gradient over a predetermined threshold lies, that is for example, greater than Is zero and thus the slip speed increases, this may after the inventive method recognized be and for example, a much more comfort-reducing measure for Avoid overloading the clutch selected be taken, for example, a measure that instead of the category "critical 1 "now the category" critical 2 "springs.

In order to Now, the invention provides a method for predicting an overload an automatically operated Clutch a vehicle and avoid overload. Dependent on the severity of the predetermined overload, i. So of the degree the predetermined overload become different measures according to the present invention to avoid overloading taken. these can for example, in an increase the overpressure on the clutch, reducing the engine torque by an engine intervention, a faster tightening of the clutch or a combination of said or other additional measures to protect the coupling when starting and shifting.

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

Claims (11)

A method for predicting an overload of an automatically actuated clutch of a vehicle during a slip phase and to avoid overloading, characterized in that the enlisted during a predetermined first period of the slip phase energy is determined and / or the current temperature of the clutch is detected and Based on the expected second period of the slip phase of the expected energy input into the clutch and / or the expected clutch temperature is determined and taken depending on the expected energy input and / or the expected clutch temperature measures to avoid overloading. Method according to claim 1, characterized in that that the measures to avoid overloading the clutch selected become dependent the expected energy input and / or the expected clutch temperature. Method according to claim 1 or 2, characterized that the measures to avoid overloading the clutch selected become dependent the first period of the slip phase and / or the expected second period of the slip phase. Method according to one of the preceding claims, characterized marked that the measures to Avoid overloading the clutch selected become dependent the current gear of a transmission in the drive train of the vehicle and / or the speed of the vehicle. Method according to one of the preceding claims, characterized marked that the measures to Avoid overloading the clutch selected become dependent the current friction of the clutch and / or the gradient the current slip speed of the clutch. Method according to one of the preceding claims, characterized marked that the measures to Avoid overloading the clutch selected are determined by thresholds of selection parameters. Method according to Claim 6, characterized that ranges between thresholds are formed within whose selectable activities to avoid overloading The coupling can be classified in such a way that depending the threshold ranges of the selection parameters the measures selected become. Method according to one of the preceding claims, characterized characterized in that the second period of the slip phase based the degraded slip speed is determined. Method according to one of the preceding claims, characterized characterized in that by means of the measures for avoiding the overload the clutch increases the gradient of reducing the slip speed. Method according to claim 9, characterized in that that the degree of overpressure the clutch increased is and / or the clutch is closed and / or that of the Clutch to be transmitted Engine torque is reduced. Apparatus for carrying out the method according to one the preceding claims, with an actuator for actuation a clutch in the drive train of a vehicle and a control device for controlling the actuator, characterized in that the control device for determining the introduced into the clutch during a slip phase Friction energy and to choose measures to avoid overloading the coupling is formed from a plurality of such measures, and activates the actuator according to the selected measures.