DE102017223143A1 - Method for operating an electro-hydraulic control device and electro-hydraulic control device - Google Patents

Abstract

Proposed is a method for operating an electro-hydraulic control device (1), in particular for a transmission of a motor vehicle, in which a plurality of electrically actuated valves (3, 4) in each case via a current signal (11, 12), a hydraulic pressure value is set to a Hydraulic switching system (2) of the control device (1) is transmitted, and in each case a dither modulation for reducing a static friction of the respective valve is impressed, in which the current signal (11, 12) is periodically changed by a superimposed dither signal, whereby from the valve a pressure pulsation ( 19, 20) is transferred to the hydraulic switching system (2). According to the invention, at least one first dither modulation of a first valve (3) is determined as a function of at least one second dithering of a second valve (4) such that a total pulsation (25) of the hydraulic switching system (2) resulting from the superposition of the pressure pulsations (19, 20 ) At least these valves (3, 4) results is minimized. Furthermore, an electro-hydraulic control device is proposed.

Description

The present invention relates to a method for operating an electro-hydraulic control device, in particular for a transmission of a motor vehicle, according to the closer defined in the preamble of independent claim 1. The invention further relates to an electro-hydraulic control device, in particular for a transmission of a motor vehicle, according to the General term of the independent claim.

From the prior art, for example from the DE 10 2008 000 304 A1 , Methods for operating a valve device of a transmission device are known, in which a dither modulation for controlling electric or electronic pressure regulators is used to prevent undesirable frictional effects. Dither modulation can lead to unwanted pressure pulsation.

The invention has for its object to provide a method and an electro-hydraulic control with improved valve control.

The problem underlying the invention is solved by the features of the independent claims. Further advantageous embodiments will become apparent from the dependent claims and the drawings.

A method for operating an electro-hydraulic control device is proposed. The electro-hydraulic control device is preferably a transmission of a motor vehicle or a hydraulic device whose working medium is controlled by electrical signals. In this method, a hydraulic pressure value is set in each case via a current signal at a plurality of electrically operable valves, which in turn is transmitted to a hydraulic switching system of the control device. In such valves, at least one valve tappet is preferably arranged in each case in a valve housing, so that one or more inlets and outlets are alternately opened or closed by the valve tappet. The opening and closing of the valve stem is usually delayed by acting between it and the housing stiction - also known as slip-stick effect. Negative result of this friction effect is a hysteresis in the implementation of the specification in the valve control. In order to reduce the static friction of the respective valve, a dither modulation is impressed, in which the current signal is changed periodically by a superimposed dither signal. In this way, a pressure pulsation is transmitted to the hydraulic switching system in the range of the set pressure value. The dither signal preferably has the effect that the valve tappet or an armature operatively connected thereto is impressed with a vibratory motion and thus better positioning accuracy can be positioned.

At least one first dither modulation of a first valve is determined as a function of at least one second dither modulation of a second valve. The determination of the first dither modulation based on the second dither modulation causes a total pulsation of the hydraulic shift system to be minimized. The total pulsation results from the superimposition of the pressure pulsation of at least these two valves. A pulsation is preferably to be understood as a dynamic pressure change of the working medium to be controlled. The two dither modulations can be dynamically adapted to each other during operation, so that each sets an ideal pressure pulsation, which in turn causes an extinguishing total pulsation. The lower the total pulsation, the lower the perceptible vibrations that are noticeable in the vehicle, for example. The dither modulation can preferably be started automatically by a control unit if the unwanted vibrations are detected by it. After the values necessary to compensate for the pressure pulsations have been detected, the parameters of the dither modulations can preferably be set such that the pressure pulsations are opposite and subtractive overlapping.

It is advantageous if the first dither modulation is determined in such a way that its pressure pulsation is in opposite directions at least at one optimization location of the hydraulic switching system for pressure pulsation of the second dither modulation. If the pressure pulsations of both dither modulations are opposite to each other, they essentially cancel each other out. The optimization site is preferably an arbitrary area in the hydraulic switching system, wherein it may be arranged, for example, in a bend region of a fluid line or substantially centrally in the switching system between the two valves. Depending on the location considered, a different pressure pulsation may occur. Since the starting point or a hypocenter of the unwanted vibrations or vibrations can change as a result of a temperature change or the operating state, the optimization location is preferably in each case that region in the hydraulic switching system in which the maximum vibrations occur. In this way, audible and noticeable vibrations in the motor vehicle can be eliminated promptly to their formation.

It is an advantage if, to minimize the total pulsation, the first Dither modulation is phase shifted to the second dither modulation. The electrohydraulic control device preferably comprises a control unit, by means of which on the one hand the total pulsation in the system, or its phase and amplitude, and on the other hand the necessary phase shift are determined so that the total pulsation can be reduced. The first dither modulation is then preferably phase-shifted as a function of the determined data. If necessary, the phase offset can be readjusted in the further course in order to achieve a more ideal pulsation behavior. The two pressure pulsations preferably extend relative to one another such that an amplitude peak of one pressure pulsation intersects an amplitude valley of the other pressure pulsation. In this way, a subtractive superimposition arises, in which the two pressure pulsations essentially cancel each other out, as a result of which a small or, ideally, no appreciable total pulsation is set. This makes it possible to keep the total pulsation of the hydraulic switching system at a low level even with changing environmental influences or operating conditions.

Advantageously, to minimize the total pulsation, a dither amplitude of the first dither modulation is changed to that of the second dither modulation. The dither amplitude is preferably parameterized for the optimization point to previously determined ideal values.

Furthermore, it is advantageous if the total pulsation occurring there is determined at the at least one optimization location of the hydraulic switching system. The total pulsation preferably results from the superposition of the pressure pulsations of both valves. The pressure pulsation depends, inter alia, on the strength of the effects of the adhesion slip effect. The adhesive slip effect or the hysteresis effect is reduced by the connection of the dither modulation, so that the pressure pulsation of the respective valve also changes and, ideally, the total pulsation is optimized.

The total pulsation present at the optimization site is advantageously determined by a computer simulation and / or by empirical real experiments. The analysis and design of the hydraulic system with regard to the dither-induced pressure pulsation preferably takes place by the simulation or empirical determination of system relationships, such as the drive current and the resulting pressure behavior at the relevant pressure transfer point or the optimization location. The control unit of the hydraulic system is preferably designed to individually determine the amplitude and / or phase position for each electrohydraulic actuator or the valves based on these empirical values or calculations and thus adapt them to one another in order to set the total pulsation to an ideal value.

It is advantageous if the total pulsation present at the at least one optimization location is sensed. After the total pulsation has been determined, the dither phase and / or the dither amplitude can be adjusted as a function of the sensory total pulsation while influencing the system behavior.

It is an advantage if the total pulsation present at the at least one optimization site is detected directly via a pressure sensor arranged in the hydraulic switching system and / or indirectly via a sensor arranged outside the hydraulic switching system. The sensor is preferably designed to measure an acceleration and / or vibration of a line of the control device. The pressure sensor is preferably arranged at a relevant pressure transfer point, wherein the total pulsation or its phase and amplitude are measured directly by means of the pressure sensor. Depending on the detected values, the first dither modulation with a correspondingly selected phase offset can then be switched on. Alternatively, it is conceivable to measure the total pulsation indirectly. For this example, the acceleration or vibration of a cooling oil pipe or its body sound is measured and made based on the measurement results, the setting of the dither.

The determined total pulsation is advantageously analyzed, derived in a map for controlling the at least one first valve and / or stored in a control device of the control device. The characteristic diagram preferably comprises the phase position and / or the amplitude. The dither modulation or its dither amplitude and / or dither phase to be changed is preferably determined as a function of the stored characteristic map.

It is advantageous if the map is designed taking into account system frame conditions of the control device. System frame conditions are preferably different hydraulic operating states and temperature ranges in which the dither modulation is to be activated and synchronized.

Another advantage is when the dithering of several valves to each other and / or be set in dependence on each other. The valve with the greatest influence on the total pulsation is preferably determined and its dither modulation is set first. For example, in multi-step automatic transmissions or generally electro-hydraulic control devices, a plurality of valves and / or Pressure regulator involved and acted upon by a dither. If the dither modulations for the individual valves are selected independently of one another, this can lead to strong vibrations of the hydraulic switching system and consequently to an undesirably high total pulsation, due to the different hydraulic pressure values resulting from the stick-slip effect of the valves. In order to set the total pulsation low, the parameters of the individual dither modulations are coordinated so that they are in opposite directions and thus essentially cancel each other out. As a result, the ride comfort can be reduced by reduced vibrations or vibrations of the hydraulic shift system in a simple manner.

The phase angles of the dither modulations of the valves are advantageously matched to one another. In this case, the dither modulations of at least two valves are started with respect to one another with a time offset and / or adjusted in phase with one another. The phase offset is preferably based on a common reference phase. In this case, the control device is preferably designed to activate the dither modulation via a switch, the dither modulation starting at a defined phase. To superimpose the two valves with matched dither modulations, the dither modulations can be started with a time offset corresponding to the necessary phase offset. The current signals are preferably supplied with the same time base, so that the frequencies can not shift to each other. Likewise, the amplitude for the optimization location can be parameterized according to the characteristic curve. Alternatively or additionally, it is advantageous if the two dither modulations are parameterized in the correct phase, wherein preferably the current signals can be acted upon by the control device with a phase angle and / or amplitude. The current signals or their current regulator are preferably synchronized and refer to a common reference phase, which then refers to the phase offset for all current signals. By way of the design of the dither modulation according to the characteristic diagram, the optimum phase position and / or amplitude for a minimum total pulsation can be set for the optimization location.

Further proposed is an electro-hydraulic control device, in particular for a transmission of a motor vehicle. The electro-hydraulic control device has a hydraulic switching system for the hydraulic switching of at least one component and a plurality of electrically actuatable valves. By means of a control device, the valves are each with a, in particular pulse width modulated, current signal controllable to set a hydraulic pressure value which is transmitted to the hydraulic switching system. By the controller Dithermodulation for reducing a static friction of the respective valve can be impressed. The dither modulation causes the current signal to be periodically changed by a superimposed dither signal, whereby the valve transmits pressure pulsation to the hydraulic switching system in the range of the set pressure value. The control device is designed to carry out a method according to the preceding description, wherein said features may be present individually or in any desired combination.

By applying the current signal with the dither modulation, the current signal is substantially pulse width modulated. Since the RMS current is preferably proportional to the valve circuit and thus to the pressure or volume provided, the dither signal results in pressure pulsations of proportional amplitude and frequency of dither modulation. By adapting the dithering of the individual valves to each other, in particular by equating the dithering periods and / or phase shifting of the dithering modulations, it is possible to adjust them in such a way that they are in opposite directions and essentially cancel each other out.

• 1 eine stark schematisierte Blockschaltbilddarstellung einer elektrohydraulischen Steuervorrichtung
• 2 ein pulsweitenmoduliertes Stromsignal mit Dithermodulation,
• 3 eine an einem Ventil gemessene Druckpulsation und
• 4 eine an einem Optimierungsort gemessene Druckpulsation.

The invention is explained in more detail with reference to drawings. Show it:

• 1 a highly schematic block diagram representation of an electro-hydraulic control device
• 2 a pulse width modulated current signal with dither modulation,
• 3 a measured at a valve pressure pulsation and
• 4 a pressure pulsation measured at an optimization site.

The 1 shows an electro-hydraulic control device 1 , Such control devices 1 find use, for example, in transmissions of motor vehicles as a hydraulic control unit or oil supply. The control device 1 has a hydraulic shifting system 2 for the hydraulic switching of at least one component. The component may be, for example, a cooling oil line. The switching system 2 has a first and a second electrically actuated valve 3 . 4 on. The valves 3 . 4 are by means of a control unit 5 controllable with a current signal to set a hydraulic pressure value, which is transmitted to the hydraulic switching system. In such valves 3 . 4 often occurs the so-called static friction effect, through which the valves 3 . 4 open jerky and thus arise control inaccuracies.

In order to eliminate these control inaccuracies, the valves 3 . 4 each acted upon by a dither, so that not shown valve tappet or armature for moving the valve stem are placed in a slight "shaking". The so-called dithering prevents the static friction effect. The current signals (cf. 2 ) of the valves 3 . 4 are pulse width modulated, which means that the pulse width is superimposed by means of a dither signal and periodically changed, whereby the valves 3 . 4 one pressure pulsation each 6 . 7 on the hydraulic shifting system 2 is transmitted.

From the superimposition of both pressure pulsations 6 . 7 the two valves 3 . 4 results in a total pulsation 8th of the hydraulic system 2 , An unfavorable or too high total pulsation 8th can lead to vibrations and / or vibrations in the motor vehicle, which negatively affect the ride comfort. This can be avoided by setting the first dither modulation of the first valve as a function of the second dither modulation of the second valve such that the total pulsation 8th of the hydraulic system 2 is minimized. For this purpose, the pressure pulsations 6 . 7 both valves 3 . 4 influenced with the respective Dithermodulation that they are in opposite directions and thus essentially extinguish (see. 2 to 4 ).

In 1 is the total pulsation 8th represented in an undesirable manner, since the two pressure pulsations 6 . 7 do not extinguish. To obtain the required parameters, has the hydraulic switching system 2 a pressure sensor 9 on, by means of which the total pulsation 8th at an optimization site 10 is detected. The optimization site 10 is a job in the hydraulic shift system 2 at which the total pulsation 8th is increased compared to other bodies. The pressure sensor 9 is preferably along the hydraulic shift system 2 traversable. Alternatively, there are several pressure sensors 9 at different points of the switching system 2 arranged. According to an alternative embodiment, it is conceivable that the total pulsation by means of an outside of the switching system 2 arranged indirect sensor is detected. The pressure sensor 9 determined, for example, an acceleration and / or vibration of a not shown line of the control device 1 ,

The pressure sensor 9 recorded measured values are in the control unit 5 deposited, so that a map for optimal control of the individual dither can be done to minimize the pressure pulsation.

The control unit 5 is designed such that the parameters of the individual valves 3 . 4 can be set individually.

The electro-hydraulic control device may comprise a plurality of valves and respective associated dither modulations.

In the following figures, the effects of the dither modulation of the valves will now be considered 3 . 4 to be discribed.

2 shows two pulse width modulated current signals 11 . 12 with impressed dither modulations of two valves (cf. 1 ). The current signals 11 . 12 are each proportional to the adjusting valve position of the valves 3 . 4 and thus to the provided pressure or volume of the switching system 2 set. Due to the dither modulation, the current signals 11 . 12 each a proportional dither amplitude 15 . 16 on. Furthermore, the dither periods are also 17 . 18 both dither modulated current signals 11 . 12 equated to each other. The two current signals 11 . 12 each have a pulse width modulated cycle time 13 . 14 on. The cycle times 13 . 14 both current signals 11 . 12 are preferably the same.

The equation or adaptation of both current signals 11 . 12 Preferably, each other is based on that of the pressure sensor 9 recorded data from which a map is derived. Depending on the measured values, it is determined which parameters (amplitude and / or period) of a dither modulation must be changed so that the two current signals 11 . 12 are in opposite directions. The current signals 11 . 13 are then subjected to the respective dither modulation, preferably a dither modulation is adapted to the other, so that the pulse width modulated clock time 13 . 14 , the dither amplitude 15 . 16 as well as the dithering period 17 . 18 set at which the current signals 11 . 12 phase shifted and / or the dither amplitude 15 . 16 will be changed. The dither modulation allows the two current signals 11 . 12 have substantially the same parameters and thereby essentially extinguish when they are in opposite directions. Because the current signals 11 . 12 proportional to the valve position of the valves 3 . 4 are changed with the dithering of the current signals 11 . 12 also the pressure pulsation which following in the 3 and 4 is described.

The 3 and 4 show two from the dither modulations of both valves 3 . 4 resulting pressure pulsations 19 . 20 , The two pressure pulsations 19 . 20 each have a pulsation period 21 . 22 these being due to the dither modulations of both current signals 11 . 12 (see. 2 ) are set substantially the same as a function of each other. Furthermore, pulsation amplitudes are also 23 . 24 substantially identical to each other.

To the total pulsation 25 (see. 4 ) are the pulsation amplitudes 23 . 24 by the same period of the pulsation periods 21 . 22 preferably aligned with each other so that the pressure pulsations 19 . 20 are ultimately in opposite directions, so that the wave crests and the troughs of both pressure pulsations 19 . 20 overlay and thereby subtract. In order for a subtractive overlay to occur, the amplitude peaks of the first pulsation amplitude must therefore intersect the amplitude valleys of the second pulsation amplitude.

If the two pressure pulsations 19 . 20 can deviate from one another in the course of time or whose amplitude peaks and amplitude valleys no longer intersect, can be determined by acquiring the measured values with the aid of the pressure sensor 9 as well as the analysis and evaluation of the control device on the basis of the characteristic curve an optimization be made, for example, by changing the first dither modulation of the first pressure pulsation, for example phase-shifted.

Through these idealized pressure pulsations 19 . 20 results in a subtractive total pulsation 25 in which the pulse amplitudes 23 . 24 (see. 3 ) preferably cancel because they are superimposed in the ideal case by the dither or the adaptation of the first dither to the second dither. An undesirable total pulsation 26 arises, for example, when the opposing pressure pulsations 19 . 20 are superposed with the dither modulations so that the amplitude peaks of both pressure pulsations 19 . 20 cut and not as desired amplitude peaks with the amplitude valleys.

The present invention is not limited to the illustrated and described embodiments. Variations within the scope of the claims are also possible as a combination of features, even if they are shown and described in different embodiments.

LIST OF REFERENCE NUMBERS

1

control device

2

switching system

3

first valve

4

second valve

5

control unit

6

first pressure pulsation

7

second pressure pulsation

8th

Gesamtpulsation

9

pressure sensor

10

Optimierungsort

11

first current signal

12

second current signal

13

first pulse width modulated cycle time

14

second pulse width modulated cycle time

15

first dither amplitude

16

second dither amplitude

17

first dithering period

18

second dithering period

19

first pressure pulsation

20

second pressure pulsation

21

first pulsation period

22

second pulsation period

23

first pulsation amplitude

24

second pulsation amplitude

25

subtractive total pulsation

26

unwanted total pulsation

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102008000304 A1 [0002]

Claims (13)

Method for operating an electrohydraulic control device (1), in particular for a transmission of a motor vehicle, in which a hydraulic pressure value is set on a plurality of electrically actuatable valves (3, 4) via a current signal (11, 12) which is based on a hydraulic switching system ( 2) of the control device (1) is transmitted, and in each case a dither modulation for reducing a static friction of the respective valve is impressed, in which the current signal (11, 12) is periodically changed by a superimposed dither signal, whereby from the valve a pressure pulsation (19, 20 ) is transmitted to the hydraulic switching system (2), characterized in that at least a first dithering of a first valve (3) in response to at least a second dithering of a second valve (4) is set such that a total pulsation (25) of the hydraulic switching system (2), from the superposition of the pressure pulsations (19, 20) to at least these valves (3, 4) results, is minimized. Procedure after the previous one Claim 1 , characterized in that the first dither modulation is set such that its pressure pulsation (19, 20) at least at one optimization location (10) of the hydraulic switching system (2) for pressure pulsation (19, 20) of the second dithering in opposite directions. Procedure according to one of the previous Claims 1 to 2 , characterized in that to minimize the total pulsation (25) the first dither modulation is phase shifted to the second dither modulation. Procedure according to one of the previous Claims 1 to 3 , characterized in that to minimize the total pulsation (25) a dither amplitude (15, 16) of the first dither modulation is changed to that of the second dither modulation. Procedure according to one of the previous Claims 2 to 4 , characterized in that the locally occurring total pulsation (25) is determined at the at least one optimization location (10) of the hydraulic switching system (2). Procedure according to one of the previous Claims 2 to 5 , characterized in that the total pulsation (25) present at the optimization site (10) is determined by a computer simulation and / or by empirical real experiments. Procedure according to one of the previous Claims 2 to 6 , characterized in that the total pulsation (25) present at the at least one optimization site (10) is detected by sensors. Procedure after the previous one Claim 7 , characterized in that the total pulsation (25) present at the at least one optimization location (10) is detected directly via a pressure sensor (9) arranged in the hydraulic switching system (2) and / or indirectly via a sensor arranged outside the hydraulic switching system (2). Procedure according to one of the previous Claims 6 to 8th , characterized in that the determined Gesamtpulsation (25) is analyzed, derived a map for controlling the at least one first valve and / or in a control device (5) of the control device (1) is deposited. Procedure after the previous one Claim 9 , characterized in that the map is designed taking into account system frame conditions of the control device (1). Procedure according to one of the previous Claims 1 to 10 , characterized in that the Dithermodulationen several valves (3, 4) to each other and / or are determined in dependence on each other, wherein preferably the valve (3, 4) determined with the greatest influence on the total pulsation (25) and its dither modulation set first becomes. Procedure after the previous one Claim 11 , characterized in that the phase positions of the dither modulations of the valves (3, 4) are matched to each other, wherein the Dithermodulationen least two valves (3, 4) are started to each other with a time offset and / or the Dithermodulationen, in particular with respect to a common reference phase be set to each other out of phase. Electrohydraulic control device (1), in particular for a transmission of a motor vehicle, having a hydraulic switching system (2) for hydraulically switching at least one component, a plurality of electrically actuatable valves (3, 4) and a control device (5), by means of which the valves (3, 4) each with a current signal (11, 12) are controllable to set a hydraulic pressure value, which is transmitted to the hydraulic switching system (2), and by means of the respective dither modulation for reducing a static friction of the respective valve can be impressed, in which the current signal (11, 12) is periodically changed by a superimposed dither signal, whereby a pressure pulsation (19, 20) is transmitted from the valve (3, 4) to the hydraulic switching system (2), characterized in that the control unit (5) Implementation of a method according to one or more of the preceding claims is formed.

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