DE102007034203A1 - Clutch`s wear detection method for motor vehicle, involves detecting whether torque is delivered with or in proximity of maximum transferable torque of internal-combustion engine when counter is greater than zero - Google Patents

Abstract

The method involves setting a counter to zero, and detecting whether a slip arises in a clutch (4). The counter is increased when a slip is detected. A detection is made whether a torque is delivered with or in the proximity of a maximum transferable torque of an internal-combustion engine (2) when the counter is greater than zero. The slip of the clutch is detected, and the counter is reduced when no slip is present in the clutch. A determination is made that wear of the clutch is present, when the counter is equal to or larger than a given threshold value. An independent claim is also included for a device for detection of clutch wear in a clutch arranged between an engine and a transmission.

Description

The The invention relates to an automatically controlled clutch in the drive train a motor vehicle with a clutch actuating motorized actuator, which is controlled by a sensor that determines the travel of the actuator and additional Monitored parameters. A wear signal can be generated when the clutch is an overly different Operating behavior has.

It is known in motor vehicles with conventional internal combustion engines between the transmission and the internal combustion engine in the drive train to arrange a clutch, so when changing a gear stage the clutch is opened can be and then can be closed again after changing the gear stage. Such clutches are also known as automatically controlled clutches known, especially in automated manual transmissions.

It is known, in the automatically controlled clutches a slip control to integrate to avoid situations where a discrepancy between an indicated and the actual clutch torque is present. When such a small discrepancy occurs, the Slip control the clutch target position with the aid of the control unit.

These known automatic clutches usually work as friction clutches, the frictional engagement of the associated control unit of the clutch controlled becomes. The friction linings Such couplings are subject to inevitable wear, resulting in Episode has that the maximum transferable torque of the clutch below the torque that can be generated by the engine drops and the clutch "slips" occurring frictional heat can in extreme cases be destroyed lead the clutch.

Therefore, it is for example from the DE 196 39 291 C1 It is known to monitor parameters correlated with the coupling welding in an automatically controlled coupling. When in the DE 196 39 291 C1 proposed solution, the coupling sensor system includes at least one signaling device whose signals reproduce each transmitted by the clutch torque or allow to determine, or that sensors are present whose signals reflect whether the clutch operates with slip. The occurring during slip value of the transmitted torque of the clutch is assigned to the respective value of the placement of the actuator as a transferable torque from the clutch. A warning signal is generated when the maximum attainable when exhausting the travel clutch torque falls below a threshold.

To is regularly the Travel of the actuator detected and determined from which Value the maximum transferable torque from the clutch exhaustion of for the control unit available has standing travel. If the transmittable moment is too small is closed on clutch wear.

In a method that in the DE 36 01 708 A1 is described, the current frictional power is calculated for friction performance monitoring of a friction clutch and for monitoring the Reibbelagverschleißes from the currently transmitted by the clutch torque and the difference between the input side and the output side speed of the clutches. From this the average friction loss of the coupling process is determined. The mean friction values of successive coupling operations are summed and compared to a maximum friction coefficient allowed for the clutch, taking into account standard values for cooling. If the maximum permissible friction power value is exceeded, a warning signal for thermal overload of the clutch is triggered. By monitoring the slip of the clutch in the state of thermal overload, a criterion for impermissibly high wear of the friction linings of the clutch can be obtained.

In a method according to the DE 30 43 348 A1 the gripping point of the clutch is detected by detecting the operating behavior of an electric servomotor of the clutch. By detecting the electric drive current for the electric motor, the actual gripping point position of the clutch is compared with a desired value. As soon as excessive grip point migration is detected, a wear signal is generated.

From that It is the object of the invention to provide a method and a device To detect clutch wear, which is the monitoring the wear state of the clutch over a prolonged period allowed.

These The object is achieved by a method having the features of the claim 1 and a device having the features of claim 11. preferred embodiments are in the dependent claims specified.

The invention is based on the idea of monitoring an operating behavior of the clutch over a prolonged period of time, for example starting from the start of the operation of a new clutch, until a required replacement due to wear occurs. In particular, it can be ensured with the method and the device according to the invention that states in which unexpected slippage occurs in the clutch, but which are due to a natural coupling behavior or on exceptional situations that occur only once, are not considered as wear, since these unexpected slip situations can be compensated as it were by error-free behavior of the clutch below. Only when several situations of unexpected slip have accumulated, without any intermediate compensation, it is concluded, the clutch wear is present, which leads to the repeated unexpected slip.

To is in the process of the invention a counter first only set to 0; while The operation then detects whether there is an unexpected slip in the Clutch occurs. The counter is then increased when an unexpected slip is detected. If during the Operation of the counters at a value> 0 is detected, whether a torque at or near a maximum transferable Torque is output from the engine. In such situations with Delivery of a maximum transferable torque is detected, whether the clutch is in the slip state. If now there is no significant slip in the clutch, the counter becomes again reduced. The torque in the vicinity or at a maximum transferable Torque can also be for Counter readings of 0 are detected, but then preferably not the counter is reduced below 0. The steps of detecting, whether unexpected Slip occurs in the clutch and increasing the counter or decreasing the counter, if a torque at or near a maximum transferable Torque transmitted without slippage will be repeated. As long as the counter is under a predetermined Threshold remains, the clutch continues its operation. If the counter over one predetermined value increases, it is determined that clutch wear is present and a corresponding signal can be output.

For example it can be visualized on a vehicle information system and ask the driver to perform a clutch service.

Preferably is for detecting whether unexpected slip occurs in the clutch, considered the coupling temperature and the counter is only increased when the clutch temperature is within a normal operating range. exceeds The clutch temperature can be a normal operating range immediate warning signal, for example, be issued.

Preferably will increase both as well as decreasing the counters each in 1ner steps up or down. alternative it is also possible weighting to such an extent that, for example, unexpected slipping states the counter increased by two or a multiple will, while it is reduced in decreasing in single steps, so that unexpected slip conditions by several normal operating conditions with maximum torque transmission have to be compensated an increase of the counter over the Time to avoid.

To a preferred embodiment for calculating or determining whether unexpected slip in the clutch occurs, a calculation model for determining the current clutch torque based on the position of the clutch actuator used. simultaneously the torque signal of the motor, i. H. the engine output torque monitored. If the calculated clutch torque is greater than the engine torque and slipping, it can be assumed that the slip decreases as the engine speed changes. Therefore is according to the preferred embodiment, if the calculated clutch torque is above a threshold and essentially over the motor torque and the slip is a change the engine speed does not decrease but starts to get bigger, concluded that the clutch torque calculation is inaccurate is and the actual Clutch torque significantly below the calculated clutch torque lies. Because it is possible in such situations, that the torque output the coupling is reduced to such an extent that it is no longer able to with a maximum torque through to transmit the engine generated torque, these situations detected as unexpected slip.

In addition, can the friction coefficient of the clutch over a period recorded in particular, over the same period, about the method of the invention is carried out, and as additional Criterion for the determination of wear Waste of the coefficient of friction of more than a given Value to be used. Furthermore Is it possible, from a clutch characteristic using the clutch friction coefficient to extrapolate whether the clutch capacity in the full engaged position sufficient for the maximum torque provided by the engine transferred to.

For the device Preferably, a control is provided, which can perform the method steps. The necessary input signals be by sensors such as torque sensors for engine torque and / or the clutch torque, a clutch travel position sensor and / or a temperature sensor for the clutch.

following the invention will be described by way of example with reference to the accompanying drawings explains being in

1 a drive train of a motor vehicle is shown schematically; and

2 a flow chart of the method according to the invention is shown in a preferred embodiment.

The motor vehicle has an engine, for example an internal combustion engine 2 on that over a clutch 4 with a transmission, such as an automated manual transmission 6 , connected is. The gear 6 drives over a cardan shaft 8th and a differential 10 the rear wheels 12 of the vehicle. To decelerate the vehicle is a brake system 14 with a braking device 16 provided that via a brake pedal 18 is pressed. Although only the connection from the brake device 16 is placed to the left front radar, it is understood that the brake device 16 interacts with all wheels of the motor vehicle.

For controlling the load of the internal combustion engine 2 serves an accelerator pedal 19 that has a throttle 21 controls. The transmission is by means of a shift lever 23 connected. The coupling 4 is automated and is controlled by an operating unit, such. B. an actuator 25 , via a master cylinder 27 and slave cylinder 29 under displacement of an actuator 48 actuated.

The actor 25 is from a control unit, such. B. an electronic control unit 31 from controlled, which contains a microprocessor and data from, for example, a sensor 32 for the speed of the internal combustion engine (speed), a sensor 34 for detecting the wheel speed of the vehicle, a sensor 36 to detect a shift request by pressing the gear lever 23 , a sensor 38 for detecting the position of the actuator 48 the clutch 4 , a sensor 40 for the position of the actuator 25 , a sensor 42 for detecting the cooling water temperature, a sensor 44 for detecting the temperature of the intake air and a sensor 46 receives for the detection of the coupling temperature.

In the method according to the invention, in the case of coupling assembly or repair of the coupling, in particular wear parts, a counter in the controller 31 set to ZN = 0. This corresponds to step S10 in FIG 2 illustrated procedure.

During clutch operation, ie during operation of the vehicle, the controller monitors at regular intervals or continuously whether there is an unexpected slip in the clutch 4 occurs. For this purpose, for example, in step S11 from the position of the clutch actuator 38 or of the actuator 25 that with the sensor 40 respectively. 38 is detected, the current clutch torque is calculated. At the same time with a torque sensor of the engine 2 detects the torque signal of the motor. When the clutch torque is greater than the engine torque and above one in the controller 31 is set, it is examined whether the slip begins to increase, especially when the engine speed is changed.

If this is the case, the counter ZN is incremented by one in step S12. If not, the process proceeds to step S13, where it is determined whether the counter is already at a value> 0 or not. If this is not the case, then the method returns to determining whether an unexpectedly high slip is present, in step S11. Otherwise, as well as after incrementing the counter in step S12, the method proceeds to step S14, where it is determined whether the engine is outputting a maximum torque. When the engine outputs a maximum torque and at the same time it detects that in the clutch 4 there is no significant slip, the counter ZN is decremented by one in step S15 and the process returns to the determination of an unexpected slip in step S11.

Lies otherwise, in step S14, even at the maximum engine torque slip before, in step 16 it is checked if the counter already reached a predetermined threshold or not. Is the counter on a stand taller than the threshold is ZNmax, the system detects that, presumably Clutch wear is present and indicates a corresponding wear message in step S17 the driver. When the counter has not yet reached the value ZNmax, the method returns to step S11 back.

Consequently may be characterized by the fact that in step S14 in transmission of a maximum or near maximum Motor torque Mmax without slippage of the counter ZN is lowered, a any unexpectedly high slip condition in step S11 be compensated if it is not due to coupling wear, there in the state of wear the coupling of the meter ZN disproportionately in step S12 or much more often compared to a possible one Compensation increases in step S15 becomes.

The determination of the unexpected slip state in step S11 may be concurrent with whether the clutch temperature is normal. If the clutch temperature is outside a normal operating range, can also be a corre sponding This error message will be output.

Finally, parallel to the illustrated flow in 2 the clutch friction coefficient is continuously monitored over an extended period of time. From this observed clutch friction coefficient can also be concluded that a maximum transferable clutch torque value. If this approaches the maximum torque, ie, steadily decreases, and reaches the vicinity of the maximum engine torque to be transmitted, an error message can also be issued.

Of the essential aspect of the invention is that the observation a clutch wear over a extended period is possible and thus it is ruled out that wrongly wear state is closed, if otherwise abnormal performance of the vehicle is present.

2

Internal combustion engine

4

clutch

6

manual transmission

8th

propeller shaft

10

differential

12

rear wheels

14

braking position

16

braking device

18

brake pedal

21

throttle cap

23

gear lever

25

actuator

27

Master cylinder

29

slave cylinder

31

control unit

32

sensor

34

sensor

36

sensor

40

sensor

42

sensor

44

sensor

46

sensor

48

actuator

Claims (14)

Method for detecting clutch wear in one between a motor and a transmission arranged clutch, containing the steps: (a) setting a counter to zero; (b) detecting, whether an unexpected slip occurs in the clutch and increasing one counter, when a missed slip is detected; (c) if the counter is greater than Zero is detecting whether torque is at or near one maximum transferable Torque is output from the engine, detecting the slip the clutch and reducing the counter, if no significant slip present in the coupling; (d) repeating steps (b) and (c) and determining that clutch wear is present when the counter equals or bigger one predetermined threshold is. Method according to claim 1, characterized in that that in step (b) the coupling temperature is taken into account and the counter is increased, when the clutch temperature in the detection in a normal Operating range is. Method according to one of the preceding claims, characterized characterized in that in step (b) the counter is increased by one. Method according to one of the preceding claims, characterized characterized in that in step (c) the counter is decremented by one. Method according to one of the preceding claims, characterized characterized in that in step (b) for detecting whether unexpected Slip occurs in the clutch based on a detected Position of a clutch actuator a current clutch torque is calculated and compared with a motor torque. Method according to Claim 6, characterized that change the slip is observed when the current clutch torque greater than is the engine torque, and increasing the slip at a motor speed change is closed on an unexpected slip in the clutch. Method according to Claim 6, characterized that closed only to an unexpected slip in the clutch when the current clutch torque is above a predetermined threshold lies. Method according to one of the preceding claims, characterized characterized in that the friction coefficient of the clutch via a Period is recorded and when the coefficient of friction decreases is determined below a predetermined threshold that a clutch wear is present. Method according to one of the preceding claims, characterized characterized in that in step (c) the counter is reduced to minimum zero becomes. Method according to one of the preceding claims, characterized characterized in that in step (a) the counter is set to zero, if wearing parts the clutch are new. Device for detecting clutch wear in one between a motor and a transmission arranged clutch, containing several sensors for the delivery of detection signals and a controller which is programmed and adapted to the steps of the procedure according to one of the preceding claims in dependence on the detection signals perform. Device according to claim 11, characterized in that that the sensors torque sensors for the engine torque and / or contain the clutch torque. Device according to claim 11 or 12, characterized in that that the sensors contain a temperature sensor for the clutch. Device according to one of claims 11 to 13, characterized that the sensors have a sensor for a clutch actuator position included.