AT516476B1 - METHOD FOR ADAPTING THE CLUTCH POWER OF A VEHICLE - Google Patents

Abstract

The invention relates to a method for adapting a friction clutch (5) of a vehicle. In order to perform an adaptation of the switching element without influencing the driving comfort, the following steps are carried out: • operating the vehicle in a stationary or quasi-stationary operating state, wherein a first input torque (ME1) is applied to the input side of the friction clutch (5); • Applying the friction clutch (5) with a basic clutch force (FK1), which is just so large that a first input torque (ME1) can be transmitted; Temporarily changing, preferably increasing, the first input torque (ME1) to a second input torque (ME2); Measuring the output torque (MA) on the output side of the friction clutch (5) and / or determining the slip between the input side and output side of the friction clutch (5); Comparing the determined slip and / or the determined output torque (MA) with a desired range and adapting the basic clutch force (FK1) of the friction clutch (5) if the determined slip and / or the determined output torque (MA) are outside a defined target range ,

Description

Description: The invention relates to a method for adapting the coupling force of a vehicle.

DE 43 24 810 A1 describes a control method for a continuously variable transmission, wherein the slip torque of the clutch determined cyclically or countercyclically and the height of the clutch pressure is compared with a characteristic. The comparison specifies a correction value over which the characteristic is adapted.

WO 2011/124197 A1 discloses a method for controlling an automated clutch comprising a hydraulic clutch actuation system with a hydrostatic actuator whose pressure is detected. The hydrostatic actuator pressure is used for clutch characteristic adaptation.

From DE 19 903 554 A1 a motor vehicle drive train is known, which has an electronic control device, a variator for stepless drive ratio and at least one frictional clutch for transmitting the drive torque. The safety factor against slippage of the clutch is constantly kept so much lower than the safety factor of the variator against slipping that when a torque shock exceeding a certain limit occurs, the clutch slips, thereby preventing the variator from slipping ,

A method and a device for controlling the operation of a drive train of a vehicle arranged automatically actuated clutch is further known from DE 19 824 480 A1. In this case, the closing of the clutch is controlled after a gear change, when starting or while driving such that the closed position of the clutch depends on operating parameters of the drive train. It is proposed that the slip of the clutch is determined after a gear change and controlled closing of the clutch and that the clutch is further closed or completely closed when after a gear change, a predetermined slip value is exceeded for a predetermined period of time.

Furthermore, DE 198 12 629 A1 discloses a control for an automatically actuated clutch, in which by means of a pilot control characteristic to be set in each case desired-Kupp lungselements corresponding to a predetermined nominal clutch torque curve, a corresponding adjustment of the actuator is assigned. At least once during a slip phase, the actual clutch torque is calculated at a predetermined adjustment value in the following manner: First, the change in the engine speed is detected within a predetermined time. Furthermore, the present within this predetermined time mean torque determined. The actual clutch torque is then calculated in response to the change in engine speed from both the mean engine torque within that given time in conjunction with the moment of inertia. If the calculated actual clutch torque deviates from the predetermined desired clutch torque, a corrected pilot control characteristic is accordingly used in the next slip phase for setting the adjustment path corresponding to the predetermined desired clutch torques.

Furthermore, from EP 1 491 787 A1 a method and a device for adapting a stored in an electronic control device relationship between a transmittable torque of a clutch and a control variable for controlling an actuator of the clutch is known, wherein from at least one adaptation parameter calculated by the clutch transmissible torque and the control variable is assigned as updated transmissible torque.

The cited documents are mainly concerned with methods for coupling line adaptation for the compensation of, for example, series dispersion or aging influence.

Friction clutches, such as disk clutches or multi-plate clutches, in automated transmissions - for example, automatic transmissions, dual-clutch transmissions or automated manual transmissions - are subject to various variations in their characteristics, in particular a variable torque transmission characteristic. This characteristic varies, for example, over a series spread and over the runtime, which is known, for example, in the series spread of new transmissions and the aging influence of components and elements.

In addition, the behavior of friction clutches is variable with respect to, for example, the temperature (oil / switching element / hydraulic) and the rotational speeds of the clutch (input / output / differential speed). The behavior of friction clutches is subject to hysteresis effects and nonlinearities, among others.

Not least also shows the transmitted from the engine to the transmission actual torque on some errors: By faulty torque signals and thus incorrect clutch torque friction clutches are not suitably controlled, which brings a corresponding deterioration of the gear shift quality with it.

The behavior can only be considered in a normal expression in the functionality. Deviations from the normal behavior must be detected and compensated by suitable routines. Therefore, a friction clutch must go through the above-mentioned reasons during operation or in a new installation routines that can recognize any setpoint differences, and compensate for functionality accordingly.

Two approaches are known from the prior art to determine the behavior of the friction clutch and adapt in this state: 1.) The friction clutch is subjected to less pressure or force, which also correspondingly less torque can be transferred. After the input torque is kept constant, a slip begins to build up on the friction clutch that is detected. Build up too early, too fast, or too high slip, it is concluded on a friction clutch, which transmits less torque at the same pressure or the same force, as a reference system: Accordingly, more pressure or force is held at the friction clutch for other control cycles , This results in the following disadvantages: After the clutch torque determines the output torque and is lowered abge, there is a high potential that the driver notices the lack of functionality, such as a traction force. This is reinforced by the fact that the coefficient of friction usually decreases with increasing slip.

· The input speed is sometimes up quickly and must be reduced again via a pressure or force control of the slip, which is, however, often noticeable to the driver due to the increase in the drive torque.

· The increase of the drive torque is thereby exacerbated because the effect of the engine inertia is added to the input torque to brake back to the engine at synchronous speed.

The function must be suitably prepared on the pressure side or on the force side by controlling the override to a defined starting level. This starting level is contrasted with a falling ramp of low slope towards slip, and the detected slip compared to the expected response. Furthermore, the strongly increasing slip must be controlled by a pressure jump so that a controlled synchronization via clutch pressure or force is possible.

The friction clutch in this case passes through a hysteresis loop, which falling

Has pressure and force edges. The changing pressure and force edges have a corresponding disadvantageous effect on the behavior of the friction clutch.

2.) The friction clutch is operated permanently with controlled slip. As a result, can be compared continuously between input torque and clutch torque. The slip controller automatically compensates the error and the control deviation can be used for an adaptation of the feedforward control. The

Disadvantages here are as follows: The permanent slip control causes a high degree of functional effort with correspondingly high calibration and hedging costs.

· Permanent slip control can be detrimental in dynamic situations because the controller may not provide the desired control comfort in these situations.

The friction clutch is permanently operated in low slip, which is the

Increased wear and can affect the fatigue life.

Permanent slippage also causes correspondingly higher losses in the long term

System, such as negative effects on fuel consumption and transmission temperature.

The object of the invention is to avoid these disadvantages and to ensure the best possible operation of a friction clutch.

According to the invention this is achieved with the following steps: a) operating the vehicle in a stationary or quasi-stationary Betriebszu, wherein a first input torque is applied to the input side of the friction clutch; B) Applying the friction clutch with a basic clutch force, which is just so large that a first input torque can be transmitted; C) temporarily changing, preferably increasing, the first input torque to a second input torque; D) measuring the output torque on the output side of the friction clutch and / or determining the slip between the input side and output side of the friction clutch; E) comparing the determined slip and / or the determined Ausgangsdrehmo Mentes with a desired range and adapt the basic coupling force of the friction clutch when the determined slip and / or the determined output torque are outside a defined target range.

A quasi-stationary operating state is understood here as an operating state in which the relevant variables (rotational speed, torque, power, driving resistance) change only within an acceptable range.

The speed gradient remains approximately constant, the torque is maintained within an acceptable tolerance band. The acceptable range or tolerance band is predefined in the calibration of the functionality. The changes in the relevant quantities are thus so minor in a quasi-stationary state that they can still be regarded as irrelevant to adaptation.

In quasi-stationary operating conditions, the friction clutch is acted upon by a coupling force such that slightly more torque than the first input torque can be transmitted (basic holding torque).

This actuation value is maintained. As a result, the torque at the output, and thus the driving torque of the vehicle, and the resulting acceleration is defined.

In a first embodiment of the invention it is provided that the check of the slip is carried out in the drive mode of the vehicle, wherein the input torque is a drive torque. Based on the abovementioned actuation value for the first input torque, an increase in the friction clutch input torque is triggered via a positive torque request on a drive machine, which may be designed, for example, as an internal combustion engine or electrical machine, for example by increasing torque engagement. This increase can be very short and concise.

The aim is to perform the adaptation of the coupling force of the friction clutch without disturbing the normal ferry service and ride comfort. To perform the determination of the clutch slip as unnoticed by the driver, it is advantageous if the first input torque is changed for a maximum of a few seconds.

If the coupling force of the friction clutch is in a set tolerance band, a slight slip will build up in a precisely defined time range, which can be kept very short, practically without influencing the output torque. This slip is again reduced without affecting ride comfort when subsequently inducing a small reduction in drive torque. The drive torque is reduced until a synchronization of the rotational speeds occurs at the friction clutch.

If the slip is not detected as expected, the base-metal temoment can be lowered accordingly for a new test and the test be carried out again, until a defined slip is detected.

In the present invention, to achieve even more concise torque jumps at the beginning of the slip measurement, the prime mover, if it is designed as an internal combustion engine to be prepared for the expected positive torque intervention, for example by adjusting the ignition angle and the cylinder filling. As a result, the positive edge of the torque increase can be carried out even faster and thus the accuracy further increased and the comfort for the driver can be increased.

In a second exemplary embodiment of the invention may also be provided that the check of the slip is performed in overrun mode of the vehicle, wherein the input torque is a braking torque. The slip test is carried out, for example, during a fired thrust. The temporary change of the first input torque can be done by a short-term activation of the fuel cut-off - ie deactivation of the combustion in the thrust.

The fired thrust is characterized by a minimum firing torque that is not sufficiently high to compensate for engine losses. As a result, the output engine torque is effectively still negative, but just smaller than the torque in the fuel cut. When the fuel cutoff takes place no burns in the cylinder and thus no combustion torque occurs. At the engine output, the engine losses thus occur as a thrust torque.

The method according to the invention offers the following advantages over the prior art: [0044] Since the output torque remains quasi-constant, the control remains largely unnoticed by the driver; There is a clean timing, a simple and reliable detection of the slip point, since, for example, the engine torque can be controlled faster and more accurate than clutch pressure or force; - The test can be canceled at any time, for example, when a bad ter road condition is detected without the process is disturbed; [0047] The test can be repeated without loss of comfort and risk of abnormalities; - An error in the base engine torque is adjusted with, since an adaptation of the

Clutch actuation takes place on the engine torque signal; [0049] The friction clutch does not undergo any hysteresis during the actual test. This increases the reproducibility.

The invention will be explained in more detail below with reference to the figures.

1 shows the adaptation of the coupling force with a known method, FIG. 2 shows the adaptation of the coupling force with the method according to the invention, and FIG. 3 shows schematically the structure of a drive train for carrying out the method of the invention. [0053] FIG inventions to the invention process.

In Fig. 1 and Fig. 2 are each time t in the diagram a) the input speed nE of the friction clutch 5 (for example, a disc clutch or multi-plate clutch) of a vehicle, in the diagram b) the clutch torque MK, on the Friction clutch 5 reduced input torque ME, the output torque MA, and in the diagram c), the clutch force of the friction clutch 5 is applied.

In Fig. 1 at the times t1s t2, t3, the friction clutch 5 is acted upon with less and less pressure or force FK, which can be transmitted according to less clutch torque MK. After the input torque ME is kept constant, starting from the time t3, slip begins to build up on the friction clutch 5, which is de-tektiert. Build up too early, too fast, or too high slip, it is concluded on a friction clutch 5, which transmits less torque at the same pressure or the same force, as a reference system: Accordingly, for more control cycles and more pressure or force on the friction clutch maintained. The disadvantage is that from the onset of the slip, the input speed nE increases sharply and the output torque MA decreases. After detecting the slip, the slip must be reduced again via a pressure or force control by increasing the coupling force FK between the times t3 and t4. This is often noticeable to the driver (after previous break-in you can feel an increase in the clutch torque MK). Until stabilization to the original output torque Ma, the friction clutch passes through a hysteresis loop, which adversely affects ride comfort and behavior.

By contrast, FIG. 2 shows the method according to the invention for comparison. It can be clearly seen that first - between the times L and t2 - the clutch force FK is reduced to a base clutch force FKi, which is just so large that a first input torque ME1 is transmitted slip-free. In a quasi-stationary operating range from the time t2 of the vehicle, the input torque ME is temporarily increased to a second input torque ME2, resulting in a short-term increase in the input rotational speed nE of the friction clutch 5. As a result of the slip, the short-term increase in the input torque ME between t3 and t4 has minimal effect on the output torque Ma, so that the drivability and ride comfort for the driver are no longer affected. If the measured slip on the switching element within the intended range, an adaptation of the switching element is not required. If the slip is higher than intended, the activation force of the switching element must be increased. If no slip is detected, the slip measurement is repeated with reduced activation force of the switching element. After detecting the slip, the input torque ME from the increased value ME2 is temporarily reduced to a value ME3 between times t4 and t5 to transfer the clutch surfaces from the sliding friction to the stiction state before finally resetting the first input torque ME1. Thereafter, the coupling force can be increased again to the original operational value FKb.

The method according to the invention shown in FIG. 2 has the advantage, in comparison to the method shown in FIG. 1, that the output torque MA is virtually constant and the process remains largely unnoticed by the driver; A clean timing, as well as a simple and reliable detection of the slip point (motor torque or input torque ME can be controlled faster and more accurately than clutch pressure or force); [0061] the test can be stopped at any time without interrupting the procedure (for example, if a bad road condition is detected) and can be repeated without loss of comfort and a risk of abnormalities; [0062] an error in the basic engine torque can be adjusted; [0063] The friction clutch 5 does not experience hysteresis change during the actual test. This increases the reproducibility.

Fig. 3 shows a drive train 1, which is suitable for carrying out the method described, wherein at least one prime mover 2 (internal combustion engine, electric machines, power-split drive combinations) via coupling / input elements 3 - such as automatic or manual clutches, torque converter or the like - And any primary ratios 4 (planetary gear, countershaft, or the like) is drivingly connected to a friction clutch 5 and this with power (speed, torque) applied. The friction clutch 5 transmits this power via a possible secondary ratio 6 and drive elements 7 on non-illustrated drive axles.

The invention can be used both for standard drives, such as automatic transmissions, dual-clutch transmissions, automated manual transmissions, converter clutches, converter clutch in the CVT transmission, for friction clutches with coupling elements in the hybrid compound such as disconnect couplings, starting clutches, clutches and brakes, as well as in the start-stop Composite can be applied for example with separation / coupling elements.

Claims (7)

claims A method of adapting the coupling force of a friction clutch (5) of a vehicle, comprising the steps of: a) operating the vehicle in a stationary or quasi-stationary operating condition, applying a first input torque (MEi) to the input side of the friction clutch (5); b) applying a basic clutch force (FKi) to the friction clutch (5) which is just large enough for a first input torque (MEi) to be transmitted; c) temporarily changing, preferably increasing, the first input torque (ME1) to a second input torque (ME2); d) measuring the output torque (MA) on the output side of the friction clutch (5) and / or determining the slip between the input side and output side of the friction clutch (5); e) comparing the determined slip and / or the determined output torque (Ma) with a desired range and adapting the basic clutch force (FKi) of the friction clutch (5), if the determined slip and / or the determined output torque (Ma) outside a defined target range lie. 2. The method according to claim 1, characterized in that the base coupling force (FKi) and / or the underlying functional parameters of the friction clutch are reduced when no slip is detected, and that the steps a) to e) are repeated. 3. The method according to claim 1 or 2, characterized in that the basic coupling force (FKi) and / or the underlying functional parameters of the friction clutch (5) are increased when the determined slip is greater than the defined target range of the slip. 4. The method according to any one of claims 1 to 3, characterized in that the test of the slip in the drive mode of the vehicle is performed, wherein the input torque (Me) is a drive torque. 5. The method according to claim 4, characterized in that before performing step c) the ignition angle of at least one cylinder is pre-adjusted. 6. The method according to any one of claims 1 to 3, characterized in that the test of the slip is performed in overrun operation of the vehicle, wherein the input torque (Me) is a braking torque. 7. The method according to claim 6, characterized in that in step c) the fuel cut is activated.