WO2016070879A1

WO2016070879A1 - Method for ascertaining a transmission behavior of a powertrain

Info

Publication number: WO2016070879A1
Application number: PCT/DE2015/200485
Authority: WO
Inventors: Ulrich Neuberth; Michael Reuschel
Original assignee: Schaeffler Technologies AG & Co. KG
Priority date: 2014-11-04
Filing date: 2015-10-27
Publication date: 2016-05-12
Also published as: DE102014222457A1; CN107076228A; DE112015004996A5; CN107076228B; DE112015004996B4

Abstract

The invention relates to a method for ascertaining a transmission behavior of a powertrain comprising a drive unit, a transmission, and a friction clutch arranged between the two and controlled in an automated fashion by means of a clutch actuator. A predefined clutch set-point torque is impressed onto the clutch actuator by means of the control device and the clutch actuator sets, by means of an actuation mechanism, an output torque having at least one characterizing output variable, a transmission behavior of the friction clutch changing over time depending on properties of the actuation mechanism and the friction clutch. In order to maintain the quality of control of the friction clutch when the transmission behavior changes, the clutch actuator is impressed with a modulation variable upon an initial transmission behavior of the powertrain and with slipping friction clutch and, depending on the modulation variable, at least one output measurement variable is detected, the at least one output measurement variable is stored in a non-volatile memory in the form of a reference variable and under the same conditions output measurement variables are recurrently detected at subsequent points in time and compared to the reference variable and the transmission behavior of the powertrain is determined from said comparison.

Description

Method for determining a transmission behavior of a drive train

The invention relates to a method for determining a transmission behavior of a drive train with a drive unit, a transmission and an arranged between them, automatically controlled by a clutch actuator

Friction clutch, wherein the clutch actuator by means of a control device, a predetermined desired clutch torque is impressed and the clutch actuator by means of an actuating mechanism an output torque with at least one

characterizing output variable, wherein a transmission behavior changes over the friction clutch depending on characteristics of the actuating mechanism and friction clutch over time.

Generic drive trains with an internal combustion engine, a transmission and an arranged between them, automatically operated friction clutch have long been known. The friction clutch is controlled depending on a driver's desired torque and this fully closed, fully open or slipping operated to compensate for differential speeds between the crankshaft and the transmission input shaft and transmit the predetermined torque. The friction clutch is actuated by a clutch plate, which by means of a Actuating mechanism - including hydrostatically or hydraulically operated devices - axially controls a plate or lever spring of the friction clutch via an actuating travel. In this case, a predetermined desired clutch torque becomes an actuating path on the basis of properties of the friction clutch, such as coefficient of friction and the like, via a clutch characteristic curve or characteristic map assigned and controlled by the clutch actuator and / or regulated. This is a typical transmission behavior of the friction clutch, which may be dependent on the properties of the friction clutch, the characteristics of the actuating mechanism and, if appropriate, characteristics or operating parameters of the drive train or the vehicle equipped with this. For example, as known from DE 103 16 458 A1, a change in the friction coefficient can be detected and adapted to the friction clutch. In this case, output variables at the output of the friction clutch are evaluated without modulation of the clutch actuator and adapted on the basis of these changes in the transmission behavior.

Furthermore, from DE 10 2013 204 698 A1 discloses a method for operating a generic drive train is known in which a clutch actuator actuates a friction clutch, wherein a vibration damper is activated depending on a transmission behavior of the clutch torque via the friction clutch occurring rebounding, in which the clutch plate with a frequency-dependent correction torque is applied. An assessment of the transmission behavior over time is not provided.

The object of the invention is the advantageous development of a method for controlling a friction clutch to determine the monitoring of the transmission behavior of the drive train and, where appropriate, to adapt the transmission behavior.

The object is solved by the features of the method of claim 1. The dependent of this claims give advantageous embodiments of the method of claim 1 again. The proposed method is used to determine a transmission behavior of a drive train with a drive unit such as an internal combustion engine, a transmission, for example, with multiple switchable gears and arranged between them, automatically controlled by a clutch actuator friction clutch. The internal combustion engine is, for example, a torsionally vibrating internal combustion engine with several cylinders according to the gasoline or diesel principle. On the crankshaft, a torsional vibration damper, for example, a dual mass flywheel may optionally be arranged with at least one centrifugal pendulum. The transmission can be a manually or automatically operated gear change transmission with discrete gear pairings, a multi-speed epicyclic gearbox, a CVT transmission or a

Be dual-clutch transmission. The interposed friction clutch can be used as a forcibly opened or forced closed dry or

Wet clutch be formed. Two friction clutches may be designed in particular for use with a dual-clutch transmission as a double clutch.

The friction clutch is actuated by means of a clutch actuator which is controlled by means of a control device along an actuating travel associated with the open and closed state of the friction clutch, wherein a predetermined desired clutch torque is impressed on the clutch actuator. The dynamic and stationary setting of the desired clutch torque is carried out by means of a characteristic map or characteristic curve, in which the transmission behavior of the friction clutch and the clutch actuator is included and optionally adapted over time. For example, in the map the temperature-dependent friction coefficient of the friction tion clutch, whose long-term development, the long-term development of the clutch actuator, vehicle-specific and / or drive train-specific data such as type of internal combustion engine, weight of the vehicle, trailer operation, slope of the road, driving situation and the like are taken into account. The clutch actuator contains an actuating mechanism which, from a movement, for example a rotational movement of an electric motor, images a linear movement along the actuating travel. The actuating mechanism may include mechanical, hydrostatic and / or hydraulic actuators.

The control unit can control the clutch actuator by means of a position controller with or without feedforward control. For this purpose, the control device for forming a control circuit accesses corresponding sensors and / or algorithms for direct or indirect detection of the actuation path, the load to be applied by the clutch actuator, the operating temperature, the friction clutch and the like.

The coupling actual torque resulting from the set clutch desired torque at the output of the friction clutch is continuously determined on the basis of output variables at the output of the friction clutch on the basis of characteristic output variables, for example rotational speeds such as the rotational speed, the angular velocity, the angular acceleration and / or the like, and based on the control loop of the position controller , In this case, the control device regulates different driving situations, for example a torque to be transmitted constantly, for example based on the driver's desired torque, the weight of the vehicle, the road gradient and the like, starting and creeping situations of the vehicle, switching and stopping processes. These control processes are influenced by the current transmission behavior of the drive train, in particular the friction clutch, in that a transmission behavior via the friction clutch changes over time depending on characteristics of the actuating mechanism and friction clutch. In order to eliminate the time-varying transmission behavior, in the case of an original transmission behavior of the drive train with a slipping friction clutch, a modulation variable is imposed on the clutch actuator and at least one output measured variable is detected depending on the modulation variable. The original transmission behavior is provided, for example, when new, after maintenance, after a repair or the like. The determination of the transmission behavior takes place in slipping friction clutch, preferably during a crawl of the vehicle. The at least one output measured variable is obtained from the output variable, for example by means of phase-selective methods, for example by means of lock-in methods or the like. The output variable is stored directly or in already preprocessed, for example normalized, weighted or converted into another calculable size as a reference variable in a non-volatile memory, preferably the control device as stored. In temporally recurring sequence, for example for detecting short-term developments of the transmission behavior at intervals of minutes, hours, in some or all Kriechphasen or the like at least with slipping friction clutch and optionally at the same temperature, the same slip or the like, at least one Ausgangsmessgröße is detected and the reference size compared. Alternatively or additionally, the at least one output measured variable is used to detect long-term developments at longer time intervals, driving distances or operating times or the like under the same conditions and compared with the reference size. The output variables determined in this way are brought to the format of the reference variable and compared with the reference variable, so that the comparison of the changing transmission behavior of the drive train can be determined over time.

In turn, further process steps can be made dependent on the changing transfer behavior. For example, the map or the characteristic curve for controlling the friction clutch can be adapted by means of the clutch actuator. As a result, changes in the transmission properties, such as a changing coefficient of friction and the like, or a changed behavior of the clutch actuator, in particular the actuating mechanism, can be compensated. Furthermore, if one or more predetermined thresholds are exceeded, entries can be output in an error memory of the control device and / or warnings of the driver.

According to an advantageous embodiment, the modulation quantity is formed as a modulation moment with a predetermined frequency pattern. This means that the clutch desired torque is superimposed with a modulation torque having a predetermined frequency pattern, in the simplest case a sinusoidal modulation moment. It has proven advantageous for most applications to provide a frequency pattern with frequency components less than or equal to 20 Hertz.

From the output variable, for example an output torque, the at least one output measured variable can be calculated as the output measured variable by a phase-selective method. Here, the Ausgangsmessgröße be an output speed of the friction clutch and / or at least one output acceleration of the friction clutch. The at least one output measured variable serves as a signal response to the modulation variable introduced by means of the coupling actuator, such as modulation moment. A changed transmission behavior can be determined in the form of frequency responses of the rotational speed and the acceleration as a function of the frequency pattern of the modulation variable which is always applied identically.

In order to reduce or avoid the perceptibility of this monitoring and identification of changes in the transmission behavior for the driver and possibly passenger, the frequency pattern for achieving the at least one output measured variable is determined such that the frequency responses of the at least one output measured variable in a frequency range of minimum acceleration responses and maximum speed responses and for the subsequent determination of the transmission behavior always the same frequency pattern is used. In this case, vehicle-dependent examinations, for example computer-aided model calculations and / or vehicle tests for determining a frequency pattern suitable in this regard, can be carried out in advance. Thereafter, this frequency pattern is used both for determining the reference variable and the temporally subsequent output measured variables.

The transmission behavior over time is preferred based on one each

Amplitude and a phase of the at least one output variable determined. This means that by means of phase-selective measurements, for example by means of a lock-in amplifier or the like, for example, for the acceleration and the rotational speed in each case a frequency-dependent phase and amplitude is determined and from it the transmission behavior is determined. These signal responses can be used for example in the case of present juddering vibrations or the like also the detection and eradication of these by means of a software filter. In this case, it may be advantageous to evaluate the transmission behavior only when no picking vibrations are present.

It has also proven to be advantageous to perform the transmission behavior depending on a gear engaged in the gear.

For example, if a change threshold of the transmission behavior is exceeded and therefore dependent on a changed transmission behavior, the control of the clutch actuator can be adapted, for example by adapting the control parameters such as clutch characteristics, proposing maintenance or repair and / or the hardware, for example, the actuating mechanism to the changed Condition is adjusted.

In other words, it is proposed that in special slip situations such as creep of the vehicle, an excitation is switched to the clutch target torque, which is characterized in that this causes a reaction, for example, at the transmission input speed, the perceptible acceleration, for example, at the driver's seat but very low or so that it can not be perceived. This is possible, for example, in certain gear combinations or in special drive trains in selected frequency ranges. These are characterized in that the speed transmission function and the acceleration transmission function are different in this frequency range, namely that at a maximum the speed response forms an acceleration response at or near a minimum.

This frequency range is suitable for identifying the transmission behavior. Here, for example, a sine excitation can be used to identify the frequency response. Assuming that the frequency response in the form of magnitude and phase at this frequency has a defined effect on the overall frequency response function, it can be used to assess system behavior such as transmission behavior.

With ongoing adaptation of the transmission behavior higher torque uniformities can be allowed in clutch systems, since the vorzuhaltende, deteriorated over time transmission behavior in the friction clutch in new condition does not need to be maintained. Thus, other design parameters of the friction clutch can be optimized, for example, the torque capacity, wear, production costs and the like.

The proposed method can alternatively or additionally also be used for the identification and compensation of vibrations at expected frequencies, for example when controlling an electric machine in a hybrid drive train.

The invention can be used in vehicle projects with automated clutch actuation to support active damping of the powertrain.

The invention will be explained in more detail with reference to the single FIGURE. This shows a diagram of a transfer behavior over the excitation frequency. In the figure, for example, amplitudes of frequency response functions determined from vehicle simulations are plotted against the excitation frequency of, for example, a sinusoidal frequency pattern. The frequency response functions represent the speed response in the form of the output measure of speed and the output measure of acceleration on the transmission input shaft of a powertrain. This results in a frequency response up to 20 Hz with frequency ranges B1, B2, in which a high speed but a low acceleration response is given by means of a modulated on the clutch desired torque modulated frequency pattern. As a result, a not disturbing or noticeable for the driver frequency modulation of the clutch actuator is possible, which is suitable for the determination and monitoring of the transmission behavior of the friction clutch and thus also for an adaptation in the changes. In this case, the amplitudes and not shown phases of the speed-dependent output measured variable are preferably determined, wherein the acceleration-dependent amplitudes and phases can be monitored in addition to and / or in monitoring to fall below a predetermined threshold. In this way, the frequency pattern can be introduced without the vehicle occupants feel this. The acquisition and evaluation of the output measured variables by means of conventional calculation methods, such as those used in lock-in amplifiers application. A simple possibility consists in the multiplication of the output variable in the form of a speed signal with the exciting sine signal of the frequency pattern or a rotational speed signal phase-shifted by 90 ° and a subsequent low-pass filtering. As a result, two values are obtained per measurement, which can be converted into an amplitude and phase of the frequency response or directly be interpreted as vector components of a corresponding pointer representation. These can be compared with a stored reference frequency response. Thus, appropriate measures for adaptation and the like can be taken.

LIST OF REFERENCE NUMBERS

B1 frequency range

B2 frequency range

Claims

claims

1 . Method for determining a transmission behavior of a drive train with a drive unit, a transmission and between them

arranged, automatically controlled by a clutch actuator friction clutch, wherein the clutch actuator by means of a control device, a predetermined desired clutch torque is impressed and the

Clutch actuator by means of an actuating mechanism adjusts an output torque with at least one characterizing output, with a transmission behavior on the friction clutch depending on

Characteristics of the actuating mechanism and friction clutch changes over time, characterized in that at an original

Transfer behavior of the drive train with slipping friction clutch the coupling actuator imprinted a modulation size and at least one output measured variable is detected depending on the modulation size, the at least one Ausgangsmessgröße stored in the form of a reference variable in a non-volatile memory, and recorded in a recurring order under the same conditions temporally subsequent output measurements and be compared with the reference size and from this comparison, the transmission behavior of the drive train is determined over time.

2. The method according to claim 1, characterized in that the modulation variable is designed as a modulation moment with a predetermined frequency pattern.

3. The method according to claim 2, characterized in that a frequency range of the frequency pattern is less than or equal to 20 Hz.

4. The method according to any one of claims 2 or 3, characterized in that the modulation size is formed sinusoidal.

5. The method according to any one of claims 1 to 4, characterized in that the at least one output variable is an output speed of the rice Bung clutch and / or at least one output acceleration of the friction clutch is.

6. The method according to any one of claims 3 to 5, characterized in that the transmission behavior in the form of frequency responses of the speed and the acceleration is determined depending on the frequency pattern of the modulation size.

7. The method according to claim 6, characterized in that the frequency pattern for achieving the at least one output measured variable is determined such that the frequency responses of the at least one output measured variable in a frequency range of minimum acceleration responses and maximum speed responses and for the subsequent determination of the transmission behavior is always the same frequency pattern is used ,

8. The method according to any one of claims 1 to 7, characterized in that the transmission behavior is determined based on an amplitude and a phase of the at least one output variable.

9. The method according to any one of claims 1 to 8, characterized in that the transmission behavior is performed depending on a gear engaged in the gear.

10. The method according to any one of claims 1 to 9, characterized in that depending on a changed transmission behavior, the control of the clutch actuator is adapted.