Method for suppressing speed-dependent vibrations in a drive train signal

Abstract

Method for suppressing speed-dependent vibrations (V(r,t))) of a non-rotating drive train device of a hybrid drive train of a motor vehicle, wherein a raw signal (s(r,t)) loaded with vibrations (V(r,t)) of at least one frequency (f(r,t)) is detected for controlling the drive train unit, wherein a rotational characteristic value of a shaft subject to torsional vibrations is detected parallel to the raw signal (s(r,t)), its amplitude is determined in a phase-selective manner and is subtracted from the raw signal (s(r,t)), wherein the rotational characteristic value is used to reconstruct the at least one frequency (f(r,t)) of the vibrations (V(r,t)) and therefrom, by means of integration, an angular position (φ(r,t)) of the vibrations (V(r,t)), characterized in that the amplitude of the vibrations is determined from the angular position (φ(r,t)) and the raw signal (s(r,t)) by means of a phase-locked loop. (V(r,t)) is determined, whereby the sine and cosine components obtained by means of the phase-locked loop and the angular position (φ(r,t)) the vibrations (V(r,t,rek)) are reconstructed, wherein a correction signal (s(k,t)) is formed from the reconstructed vibrations (V(r,t,rek)) and the raw signal (s(r,t)), wherein the method for suppressing at least one further frequency is repeated at least once with the correction signal (s(k,t)) as the raw signal, wherein the rotational characteristic value is detected from a shaft subject to torsional vibrations, and wherein the drive train device actuates a separating clutch between the shaft subject to torsional vibrations and a subsequent shaft, and the correction signal (s(k,t)) serves to control the separating clutch.

Description

The invention relates to a method for suppressing speed-dependent oscillations of a non-rotating drive train device of a drive train of a motor vehicle, wherein a raw signal, which is loaded with oscillations of at least one frequency, is detected for controlling the drive train unit.DE 10 2008 041 884 A1 discloses a method for detecting and compensating oscillations in a vehicleDE 10 2014 206 183 A1 and DE 10 2012 217 132 A1 disclose methods for reducing picking oscillations in the drive train of a vehicle.DE 10 2010 041 999 A1 discloses a method for correcting a sensor variable of a sensor and for operating a control of an actuator.DE 10 2020 000 424 A1 discloses a method for correcting a rotational angle detection of an electric machine by means of a parameter learning device. Hybrid drive trains for carrying out the proposed method are known, for example, from the publications DE 10 2021 116 688 A1 and DE 10 2020 119 189 A1. In hybrid drive trains with an internal combustion engine with torsional vibration, vibrations with typical frequencies occur, which are dependent on the rotational speed. Due to the operative connection of non-rotating drive train devices, such as actuating devices for a separating clutch between a crankshaft of the internal combustion engine and a subsequent transmission input shaft, speed-dependent oscillations are likewise induced in these drive train devices for controlling these detected drive train signals.For suppressing these oscillations, low-pass filters, band locks or the like are known to be used. These change the highly dynamic signal behavior of these drive train signals as a result of the system.The object of the invention is the development of a method for suppressing speed-dependent oscillations in a drive train, in particular in a hybrid drive train. In particular, it is an object of the invention to propose a method for suppressing speed-dependent oscillations in drive train signals without changing the dynamic behavior of these.The object is achieved by the subject matter of claim 1. The claims dependent on claim 1 represent advantageous embodiments of the subject matter of claim 1.The proposed method serves for suppressing speed-dependent oscillations of a non-rotating drive train device of a drive train of a motor vehicle.Drive trains of this type, in particular hybrid drive trains, contain an internal combustion engine with torsional vibration or a drive unit made up of an internal combustion engine with torsional vibration and at least one electric machine. The internal combustion engine delivers, on the basis of its principle, a torque which is subject to vibration as a function of rotational speed and which can be mechanically damped, for example, by means of torsional vibration dampers and / or torsional vibration dampers. Nevertheless, oscillations can remain which interfere with non-rotating drive train devices operatively connected to the drive train, such as starters, air conditioners and / or the disconnect clutch and its actuating device that couple the drive shaft of the internal combustion engine or drive unit such that it can be connected from a subsequent shaft. The detection of drive train signals for controlling these are loaded with speed-dependent oscillations of at least one frequency.In order to suppress these speed-dependent oscillations in a raw signal of the drive train signal of such a drive train device, a rotational characteristic value of a shaft with rotational oscillations is detected continuously, for example. For this purpose, in parallel, for example simultaneously, synchronously or the like with the raw signal, for example, the rotational speed, rotational acceleration, the rotational angle and / or the like of a shaft subject to rotational oscillations, for example, of the drive shaft such as, for example, the crankshaft of the internal combustion engine or a drive shaft of the drive unit, the amplitude thereof is determined in a phase-selective manner and subtracted from the raw signal. In this way, in contrast to a low-pass filter, the time response of the detected raw signal and of the corrected drive train signal can be reconstructed exactly.For example, the at least one frequency of the oscillations can be reconstructed by means of the rotational characteristic value and an angular position of the oscillation can be reconstructed therefrom by means of integration, so that a temporally exact determination of the disturbance can be detected without disturbing the signal profile of the raw signal.The amplitude of the oscillations can be determined from the angular position and the raw signal by means of a phase-locked loop (PLL). A phase locked loop yields the sine and cosine components of the oscillations for a predefined frequency. From these components and the angular position of the oscillations, the undesired oscillations can be completely reconstructed. A correction signal is determined from the reconstructed oscillations and the raw signal, for example, by forming the difference, in which the oscillations superimposed on the raw signal and the reconstructed oscillations cancel each other out. A correction signal remains in this case, which in its dynamic behavior remains largely undisturbed, so that the control and control processes of the non-rotating drive train devices, which are dependent on this correction signal, can take place reliably and at the up-to-date.When oscillations with at least one further frequency occur, the proposed method for suppressing this at least one further frequency can be repeated at least once using the correction signal as a raw signal.In a preferred manner, the non-rotating drive train device actuates a separating clutch between the shaft subject to torsional vibrations and a subsequent shaft, wherein the raw signal serves for the control as actuation of the separating clutch. For example, the drive train device can be designed as a hydraulic system with a slave cylinder that actuates the separating clutch. In this case, the raw signal is obtained from a pressure sensor for detecting a system pressure at the slave cylinder and / or a travel sensor for detecting an actuation travel of a slave cylinder piston of the slave cylinder. Due to the transmission of a torque with rotational oscillations, which is dependent on the rotational speed, via the separating clutch, the slave cylinder piston is correspondingly set into oscillations, which lead to a raw signal with oscillations, which is dependent on the rotational speed of the separating clutch and is filtered by means of the proposed method.In other words, in drive trains such as hybrid drive trains, for example, in particular with an internal combustion engine, undesirable oscillations are always present. By means of their rotational speed, oscillations are excited at different points, which are dependent on the rotational speed. For example, there is a vibration whose frequency f is proportional to the rotational speed n.Usually, a low pass filter is used to reduce the vibration. For example, in a two-six-cylinder internal combustion engine, vibrations of between 120 and 220 Hz occur, which produce a pressure vibration that varies in proportion to the rotational speed of the crankshaft of the internal combustion engine and all subsequent shafts. Although this conventional low-pass filter or band locks can suppress the undesired oscillations, they lead, on the basis of principle, to a phase shift of the drive train signal, which distorts the highly dynamic signal behavior. In addition, not only the oscillations of the undesired frequency, but also other oscillations, for example desired control pulses, are suppressed as a result.It is therefore proposed to reconstruct an angular position of the undesired oscillation in a first step by measuring the rotational speed signal of the shaft subject to rotational oscillation.In a second step, a phase locked loop is used to determine the oscillation amplitude of the undesired oscillation from the reconstructed angular position and the raw signal in which the undesired oscillation is contained. In a third step, the undesired oscillation is reconstructed from the amplitude and the angular position.In a fourth step, a filtered signal such as a correction signal without the unwanted oscillations is formed from the difference between the raw signal and the oscillations reconstructed in the third step.The invention is explained in more detail on the basis of the exemplary embodiment shown in FIGS. 1 and 2. These show: FIG. 1 is a block diagram for implementing the proposed method for suppressing speed-dependent oscillations; and FIG. 2 shows a diagram with speed-dependent oscillations and their filtering.FIG. 1 shows, for example, the block diagram 1 for carrying out the proposed method, which can be stored in a control device of a drive train and executed continuously. First, over time t, the rotational speed n(t) of a shaft subject to rotational oscillations which are undesired oscillations V(r,t) and the raw signal s(r,t) subject to rotational-oscillation-dependent oscillations of the shaft are read in.In block 2, the frequency f(r,t) of the undesired oscillation V(r,t) is determined from the rotational speed n(t). For example, the undesired oscillation V(r,t) may have a frequency f(r,t) that is twice as high as the rotational speed n(t). Thus, the frequency f(r,t) of the unwanted vibration also changes with time: f(r,t)=2*n(t).In block 3, the frequency f(r,t) is integrated over the time t, resulting in the angular position φ(r,t) of the undesired oscillation.In block 4, a phase locked loop is carried out by means of the angular position φ(r,t) and the raw signal s(r,t), from which the amplitudes A(r,t,sin) and A(r,t,cos) result as the sine component and cosine component of the undesired oscillation V(r,t). These arise due to a phase angle between the rotational speed n(t) and the undesired oscillation.In blocks 5, 6, amplitudes A(r,t,sin) and A(r,t,cos) are reconstructed as sine component and cosine component with the aid of the angular position φ(r,t) to form the corresponding oscillation components V(r,t,sin) for example with the aid of V(r,t,sin)= A(r,t,sin)*sin(φ(r,t)) and V(r,t,cos)= A(r,t,cos)*sin(φ(r,t)) and added in block 7, with the result that the rotation-speed-dependent undesired oscillation V(r,t,rek) is reconstructed.The filtered correction signal s(k,t) results in block 8 from the difference between the raw signal s(r,t) and the reconstructed undesired oscillation V(r,t,rek ).FIG. 2 shows the diagram 10 of the pressure p of a pressure sensor of a hydraulically operated drive train device for actuating a separating clutch between a shaft with torsional vibration and a separating clutch arranged downstream thereof over time t. The signal curves 11, 12, 13 of the pressure over time represent the vibration behavior of the pressure signal with different suppression of undesired vibrations, wherein a change of the actuation state of the separating clutch takes place at time t 1.Signal curve 11 represents unfiltered raw signal s(r,t). The raw signal s(r,t) is superimposed with the undesired oscillations V(r,t), which are induced by the shaft with torsional oscillations in the drive train device and thus in its pressure sensor.Signal curve 12 shows correction signal s(k1,t) filtered by means of a low-pass filter. Due to the specific behavior of the low-pass filter, a time delay of the signal occurs after the initiation of the signal change at the time t 1, so that the control of the separating clutch, for example, due to overshoots and the like, may be made more difficult.Signal curve 13 shows correction signal s(k,t), corrected by the method according to block diagram 1 of FIG. 1, with a signal change responding much more quickly after time t 1, so that the separating clutch can be controlled more precisely.List of reference characters1 Block diagram 2 Block 3 Block 4 Block 5 Block 6 Block 7 Block 8 Block 10 Diagram 11 Signal profile 12 Signal profile 13 Signal profile A(r,t,sin) Amplitude Sine component A(r,t,cos) Amplitude Cosine component f(r,t) Frequency n(t) Rotational speed p Pressure s(r,t) Raw signal s(k,t) Correction signal s(k1,t) Correction signal t1 Time V(r,t) Oscillation V(r,t,sin) Sine component Oscillation V(r,t,cos) Cosine component Oscillation V(r,t,rek) Reconstructed oscillation φ(r,t) Angular position

Claims

Method for suppressing speed-dependent oscillations (V(r,t)) of a non-rotating drive train device of a hybrid drive train of a motor vehicle, wherein a raw signal (s(r,t)) loaded with oscillations (V(r,t)) of at least one frequency (f(r,t)) is detected for controlling the drive train unit, wherein a rotational characteristic value of a shaft subject to rotational oscillations is detected in parallel with the raw signal (s(r,t)), its amplitude is determined in a phase-selective manner and is subtracted from the raw signal (s(r,t)), wherein the at least one frequency (f(r,t)) of the oscillations (V(r,t)) is reconstructed by means of the rotary characteristic value and an angular position (φ(r,t)) of the oscillations (V(r,t)) is reconstructed therefrom by means of integration, characterized in that the amplitude of the oscillations (V(r,t)) is determined from the angular position (φ(r,t)) and the raw signal (s(r,t)) by means of a phase-locked loop, wherein the oscillations (V(r,t,rek)) are reconstructed from sinusoidal components and cosine components obtained by means of the phase-locked loop and from the angular position (φ(r,t)), wherein a correction signal (s(k,t)) is formed from the reconstructed oscillations (V(r,t,rek)) and the raw signal (s(r,t)), wherein the method for suppressing at least one further frequency is repeated at least once using the correction signal (s(k,t)) as raw signal, wherein the rotational characteristic value is detected from a shaft having rotational oscillations, and wherein the drive train device actuates a separating clutch between the shaft having rotational oscillations and a subsequent shaft, and the correction signal (s(k,t)) is used to control the separating clutch.Method according to Claim 1, characterized in that the drive train device is designed as a hydraulic system with a slave cylinder which actuates the separating clutch.Method according to Claim 2, characterized in that the raw signal is obtained from a pressure sensor for detecting a system pressure at the slave cylinder and / or a travel sensor for detecting an actuation travel of a slave cylinder piston of the slave cylinder.

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