DE102014203219A1 - Method for determining a pilot control voltage of an electric motor in a hydrostatically actuated clutch system, preferably in an automated manual transmission of a motor vehicle - Google Patents

Abstract

The invention relates to a method for determining a pilot voltage of an electric motor in a hydrostatically operated clutch system, preferably in an automated gearbox of a motor vehicle, with a hydrostatic clutch actuator driven by the electric motor remaining motionless when the electric motor is supplied with the pilot voltage. In a method which ensures sufficient mechanical self-retention of the clutch while reducing the energy input at the same time, the pilot control voltage is determined as a function of a pressure in the hydrostatically operated clutch system.

Description

The invention relates to a method for determining a precontrol voltage of an electric motor in a hydrostatically actuated clutch system, preferably in an automated manual transmission of a motor vehicle, wherein when a loading of the electric motor with the pilot control voltage, driven by the electric motor hydrostatic clutch actuator remains motionless.

From the DE 10 2008 046 232 A1 a method for determining holding voltage limits of a clutch actuator is known. To determine the holding voltage of a motor in which a functionally connected to the clutch actuator of an automatic transmission remains motionless, a supposed holding voltage for a clutch actuator position is determined from a stored map and then determines an actual holding voltage for the same clutch actuator position. After a comparison of the actual holding voltage with the supposed holding voltage, an adaptation of supposed holding voltage values from the characteristic field takes place for a plurality of clutch actuator positions. This holding voltage characteristic is a load pre-control map, which is stored in an in-vehicle memory.

The DE 10 2009 008 597 A1 discloses a clutch actuator for a friction clutch, which is driven by an electric motor and controlled by a control unit, wherein an adapted current limit map is used for the precontrol of the electric motor. The current limits of the clutch actuator are determined as a function of the actuator position. The described load adaptations apply to lever actuators. Self-opening lever actuators require a certain amount of force to hold different positions. This force is related to the moment of the electric motor. The moment is proportional to the required current of the electric motor.

For lever actuators, it is assumed that the torque is also proportional to the voltage, since the ohmic resistance is constantly assumed. It is defined as a function of the coupling position, the so-called roller path, a minimum and maximum voltage. If, depending on the coupling position, a voltage is applied between these limits, the actuator will not move even when the clutch is partially closed. The minimum as well as the maximum voltage curve are continuously adjusted during operation, whereby the distance between the upper and the lower limit can be different. The adaptation to this is called load adaptation. If the clutch actuator must now be held in a position, a voltage is applied just above the minimum voltage value, the clutch actuator is then held with minimal voltage and it is thus entered as little energy as possible in the system.

This existing load adaptation can not be readily applied to a Hydrostatic Clutch Actuator (HCA) because this type of actuator has a significantly different behavior compared to a lever actuator. Hydrostatic clutch actuators, for example, from the DE 10 2010 047 800 A1 as well as the DE 10 2010 047 801 A1 are also not self-holding, but must be offset by a bias voltage to be applied in a self-holding state. Under such a hydrostatic clutch actuator is an actuator with a hydrostatic transmission path, for example, a pressure line with hydraulic fluid to understand. The pressure in the pressure line is detected by a pressure sensor. If an element connected thereto is to be moved by the hydrostatic clutch actuator, hydraulic fluid is moved in the transmission path or the pressure line, for example caused by a piston in a master cylinder which moves a piston in a slave cylinder coupled by the hydraulic fluid. If the element is to hold its position, then the hydraulic fluid rests in the transmission path, so that a hydrostatic state of the hydraulic fluid is present.

The hydrostatic clutch actuator is not self-sustaining at all operating points and over the service life. A heating of the hydrostatic path has the consequence that although a force-over-travel characteristic can be defined, this characteristic curve shifts strongly and at the same time relatively fast over the path through the temperature. The adaptation of such a characteristic for the minimum and maximum voltage to be applied is not possible with such a variable characteristic.

The invention is therefore an object of the invention to provide a method for determining pilot voltages in a hydrostatically actuated clutch system, in which the not self-sustaining actor supported by the applied bias is self-sustained. In addition, due to the conditions of higher ambient temperatures, it is to be guaranteed that only as much energy is introduced into the clutch system as is necessary in order to keep the clutch actuator in the respective position.

According to the invention the object is achieved in that the pilot control voltage in response to a pressure in the hydrostatically operated Coupling system is determined. Due to the fact that the load adaptation now relates to the pressure occurring within the hydrostatic clutch actuator and not to the roller path or the clutch position as previously, an accurate determination of the pilot voltage can be realized for hydrostatically actuated clutch systems, which ensures that the itself is not self-retaining hydrostatic clutch actuator remains motionless when applying the pilot voltage.

Advantageously, a maximum and a minimum are determined for the pilot control voltage for a pressure determined at a predetermined clutch position, wherein the hydrostatic clutch actuator remains motionless when a pressure between the maximum and the minimum occurs, and preferably a pilot voltage characteristic is formed, which consists of a maximum characteristic curve and a minimum characteristic is included. By means of this stretched by the minimum or maximum characteristics range, it is reliably possible to keep even hydrostatic clutch actuators, which are not mechanically self-retaining, with the lowest possible energy consumption even at high ambient temperatures in certain positions.

In one embodiment, a voltage jump on the electric motor of the hydrostatically actuated clutch system for adjusting a Kupplungsaktorzielwertes is set to adjust the pilot characteristic, wherein after reaching the Kupplungsaktorzielwertes at a predetermined pressure, the pilot voltage is corrected. In this way, an adaptation of the bias characteristic for a minimum or maximum applied pilot voltage, which is also referred to as a holding voltage, based on the pressure, take place.

In one variant, after reaching the clutch actuator target value, the hydrostatic clutch actuator is switched off, the pilot control voltage being corrected when the determined pressure value occurs after reconnection of the clutch actuator. Due to the voltage jump, the hydrostatic clutch actuator, which is designed to self-closing or self-closing after switching off the pilot control voltage. The pilot control voltage must therefore be increased at this pressure, in order to make the hydrostatic clutch actuator self-holding.

In a further development, the hydrostatic clutch actuator is switched on and off again for adaptation of the pilot control characteristic until, at a predetermined pressure value, the clutch actuator remains motionless. This procedure, which is also referred to as "trembling", means that a pilot control voltage, in which the hydrostatic clutch actuator remains motionless, is determined with as little energy input as possible, which not only results in a possibility of adjusting the mechanical self-holding of the clutch actuator, but also for reduction the energy input in the hydrostatic clutch actuator leads, which in turn guarantees a low temperature load of the actuator environment.

In one embodiment, a fixed, dependent on the pressure in the hydrostatically actuated clutch system pilot control characteristic is used. This has the advantage that a single, previously determined pilot control characteristic can be used for a large number of hydrostatically actuated clutch systems. Since no adaptation is necessary during operation of the hydrostatic clutch actuator, the required computing power of the control unit driving the electric motor of the hydrostatic clutch actuator is reduced. Such a fixed pilot control characteristic can be defined identically for all hydrostatically actuated clutch systems.

In a further development, the pilot control characteristic is adjusted once during the commissioning of the hydrostatically actuated clutch system to the hydrostatically actuated clutch system and remains unchanged over the life of the hydrostatically actuated clutch system. This has the advantage that the fixed pilot control characteristic is adapted only once as a function of the pressure occurring in the clutch system. This pilot control characteristic is thus adapted to a special hydrostatic clutch system and may possibly be chosen lower than if a preload characteristic is firmly defined for all the hydrostatically actuable clutch systems to be produced.

Advantageously, the pressure within the hydrostatically actuated clutch system is determined from a displacement of a touch point of a clutch. Since the touch point represents the moment at which the clutch begins to grip, which is determined by the pressure acting in the hydrostatic clutch system, the touch point can be regarded as a synonym for the pressure from which conclusions can be drawn on the pilot control voltage.

In one embodiment, the pressure is smoothed by means of a, preferably sliding, averaging. This is particularly advantageous when the pressure signal is detected by a sensor whose output signal is superimposed by a noise component. Falsifications of the pressure signal in the determination of the pilot control voltage are thus prevented, which has the consequence that a highly accurate pilot voltage is determined.

In one variant, the determined pressure above the actuator position is corrected by a hysteresis component. This is necessary because the pressure signal emitted by a pressure sensor has a significant hysteresis over the actuator position. This means that two values for the pilot control voltage are always available for one pressure. By means of such a correction, it is possible to set an unambiguous pilot control characteristic via the pressure and to base it on the determination of the pilot control voltage.

The invention allows numerous embodiments. One of them will be explained in more detail with reference to the figures shown in the drawing. It shows:

1 FIG. 1 shows a schematic structure of a hydrostatic coupling system, FIG.

2 : Pressure position characteristic in a wet clutch,

3 : a diagram illustrating the pilot control voltage value above the pressure,

4 : Behavior of the hydrostatic clutch actuator without pilot voltage (holding voltage),

5 : Behavior of the hydrostatic clutch actuator with pilot control voltage (holding voltage).

In 1 schematically is the structure of a hydrostatically actuated clutch system 1 the example of a known from the prior art, schematically illustrated hydraulic, hydrostatic clutch actuator 3 (HCA). The hydrostatically actuated clutch system 1 includes on the donor side 10 a control unit 2 , which is the hydrostatic clutch actuator 3 controls. At a change in position of the hydrostatic clutch actuator 3 and the piston 14 in the master cylinder 4 along the Aktorweges to the right is the volume of the master cylinder 4 contained hydraulic fluid 7 changed, creating a pressure p in the master cylinder 4 is built, the on the hydraulic fluid 7 via a hydraulic line 9 to the recipient side 11 of the hydrostatically actuated clutch system 1 is transmitted. The hydraulic line 9 is adapted with respect to their length and shape of the installation space situation of the motor vehicle. On the taker side 11 causes the pressure p of the hydraulic fluid 7 in a slave cylinder 4 ' a change of direction on a clutch 8th is transmitted to operate this. The pressure p in the master cylinder 4 on the donor side 10 of the hydrostatically actuated clutch system 1 can by means of a pressure sensor 5 be determined, which sends its signal to the control unit 2 outputs. The of the clutch actuator 3 traveled distance W along the Aktorweges is by means of a displacement sensor 6 determined. The displacement sensor 6 it can be the piston 14 directly traveled distance or the number of revolutions of the electric motor 15 detect which is the electrostatic clutch actuator 3 drive and indirectly determine the route in this way.

In 2 the pressure p is shown above the actuator position W. As can be seen, has the in a hydrostatically actuated clutch system 1 determined pressure p a significant hysteresis over the actuator position W. Stands the hydrostatic clutch actuator 3 eg currently 8 mm, the measured pressure for the closing branch may be 8.4 bar or 5.5 bar for the opening branch. Before using the pressure p to determine a precontrol, the pressure p must be corrected by the hysteresis fraction. In the present case, one would thus look at the mean value of the pressure p of 8,4bar - 5,5bar = 2,9bar / 2 + 5,5bar = 6,95bar and change the value of the hysteresis curves at this point of the abscissa.

In addition, it must be noted that that of the pressure sensor 5 Superimposed pressure signal is superimposed with a noise component, where usually a noise amplitude is observed by 0.3 bar. In order to smooth this pressure signal, a simple moving averaging with only a few pressure values is sufficient.

In the hydrostatic clutch actuator 3 it is a non-self-sustaining actuator, which means that in a de-energized electric motor 15 the clutch 8th mechanically opens itself or closes itself. To prevent this, the electric motor 15 of the clutch actuator 3 energized with a pilot voltage, which is also referred to as a holding voltage, so that the clutch actuator 3 remains motionless. In order to accurately determine such a pilot control voltage, a load adaptation is provided which has two components. The first part consists of a constant switching on and off, the on the electric motor 15 applied voltage, which is also referred to as "jitter", while the second portion provides an adaptation of the maximum limits or minimum limits of the pilot voltage after a voltage jump.

In 3 the pilot control voltage is shown above the pressure. In this case, a maximum characteristic curve a and a minimum characteristic curve b are distinguished, which deviate to different degrees in the different regions of the pressure p. The Vorsteuerspannungskennlinie behaves over the pressure p adequately to a characteristic that was determined on the actuator position W.

The pilot control voltage Uv is thereby determined by means of a reference bias characteristic having a minimum characteristic b and a maximum characteristic a. Will a setpoint jump, on the electric motor 15 applied voltage U in the direction of closing the clutch 8th through the control unit 2 given, this leads to a voltage jump. For a small period of time, a voltage value is set just above the voltage value corresponding to the maximum characteristic a of the reference pilot voltage. Moves the hydrostatic clutch actuator 3 not, so at this point the voltage value in the maximum characteristic a is increased, since one actually a movement of the clutch actuator 3 would have expected. With such a desired value jump adaptation, both the maximum characteristic a and the minimum characteristic b of the pilot control voltage Uv can be adjusted above the pressure p.

The detection of a desired value jump of the voltage U and thus of the clutch actuator target value can not take place from the pressure p when the pressure signal is used as the abscissa for the pilot voltage characteristic since it changes too slowly. Here, the clutch actuator target position must continue through the displacement sensor 6 be evaluated. Consequently, at the time of the abrupt change of the clutch actuator target position, the measured pressure p must be detected and the pilot voltage characteristic Uv must be adapted to this pressure value. This is done to the effect that the current pressure value is frozen and at this pressure point, the minimum characteristic b and the maximum characteristic a are changed.

In 4 is the behavior of the hydrostatic clutch actuator 3 shown without setting a pilot control voltage Uv. In this case, a position profile is shown in the four diagrams A, B, C. D respectively over the time t. When switching on and off in the control unit 2 installed controller for controlling the electric motor 15 In the diagram A, the actuator position W changes continuously by 1 mm. In diagram B, as a result of this change in the actuator position W in the hydrostatically actuated clutch system 1 impacting pressure change shown. As can be seen, the greater the change in the actuator position W over the time t, the more the pressure p increases. The on the electric motor 15 applied voltage U is shown in the diagram C, which is always formed as a result of the constant switching on and off a uniform voltage peak. However, upon reaching a certain actuator position W and thus an increase in the pressure p, a noise around the voltage U is perceived, which means that the voltage U does not switch off. This noise within the voltage U is due to the non-latching movement of the clutch actuator 3 due, which opens or closes without pilot voltage. Diagram D clearly shows the switching on and off of the controller due to the switching off of the clutch actuator 3 upon reaching the clutch actuator target position and restarting when the clutch actuator 3 is pushed out of the clutch actuator target position to recognize. The voltage U is switched very high frequency between 0 volts and 0.8 volts back and forth as soon as the pressure p in the hydrostatically actuated clutch system 1 rises above a pressure of 14 bar. This behavior results from the fact that no pilot voltage (holding voltage) to the electric motor 15 is created.

In 5 the same conditions are shown again, with the difference that the pilot voltage Uv to the electric motor 17 is applied. It can be seen from the diagrams C and D that the hydrostatic clutch actuator 3 At higher pressures p is no longer supplied with a voltage of 0 volts, but always with a small pilot control voltage Uv, which is here by 0.4 volts for pressures p above 14 bar.

With the pressure signal used, the pressure does not necessarily have to be measured directly. Alternatively, to determine the pilot characteristic also a shift of the touch point of the clutch 8th be based on. The minimum characteristic curve b and the maximum characteristic curve a of the pilot control voltage Uv, which have been changed by the adaptation, can thus be related to a path deviation of the current clutch actuator travel to the touch point. In the case of determining the touch point in a transmission control unit, this can by means of a bus system to the control unit 2 of the hydrostatic clutch actuator 3 be transmitted.

An adaptation of the pilot voltage can be simplified when for a hydrostatically actuated clutch system 1 a fixed pilot characteristic is used. With such a fixed pilot control characteristic, a single adaptation is carried out during commissioning, and the control voltage characteristic thus determined in a routine for the further operation of the hydrostatically actuated clutch system 1 as firmly accepted. Thus, there is a separate pilot control characteristic for each special clutch system.

In addition, the adaptation of the pilot characteristic can also be simplified to the effect that only a constant switching on and off (trembling) by the controller of the control unit 2 is initiated. This increases the possibility of hydrostatically actuated clutch system 1 to follow delay on a setpoint change of the voltage U, since the waiting phase due to the freezing of the pressure value in the jump adaptation omitted. In order nevertheless to allow an adaptation of the pilot control curves down, one could very slowly lower the adapted pilot control characteristic and then raise it by the dither adaptation at the points where this is necessary.

LIST OF REFERENCE NUMBERS

1

 Hydrostatically actuated clutch system

2

 control unit

3

 Hydrostatic clutch actuator

4

 Master cylinder

4 '

 slave cylinder

5

 pressure sensor

6

 displacement sensor

7

 hydraulic fluid

8th

 clutch

9

 hydraulic line

10

 donor side

11

 recipient side

12

 surge tank

13

 sniffing hole

14

 piston

15

 electric motor

a

 Maximum characteristic of the pilot control voltage

b

 Minimum characteristic of the pilot control voltage

U

 tension

uv

 pilot voltage

W

 Kupplungsaktorweg

p

 print

t

 Time

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 102008046232 A1 [0002]
• DE 102009008597 A1 [0003]
• DE 102010047800 A1 [0005]
• DE 102010047801 A1 [0005]

Claims (10)

Method for determining a pilot control voltage of an electric motor in a hydrostatically actuated clutch system, preferably in an automated manual transmission of a motor vehicle, wherein when the electric motor is acted upon ( 15 ) with the pilot control voltage (Uv), from the electric motor ( 15 ) powered hydrostatic clutch actuator ( 3 ) remains motionless, characterized in that the pilot control voltage (Uv) in response to a pressure (p) in the hydrostatically actuated clutch system ( 1 ) is determined. Method according to Claim 1, characterized in that a maximum and a minimum are determined for the pilot control voltage (Uv) for a pressure (p) determined at a predetermined clutch actuator position (W), the hydrostatic clutch actuator ( 3 ) remains motionless when a pressure (p) between the maximum and the minimum occurs, and preferably a Vorsteuerspannungskennlinie is determined, which consists of a maximum characteristic (A) and a minimum characteristic (B). A method according to claim 1 or 2, characterized in that for adapting the pilot control characteristic, a voltage jump of the at the electric motor ( 15 ) of the hydrostatic clutch actuator ( 3 ) is set to adjust an actuator position target value, wherein after reaching the Aktorpositionszielwertes at the predetermined pressure (p), the pilot voltage (Uv) is corrected. Method according to Claim 3, characterized in that, after the actuator position target value caused by the voltage jump has been reached, the hydrostatic clutch actuator ( 3 ) is switched off, whereby after reconnection of the clutch actuator ( 3 ) the pilot control voltage (Uv) is corrected when the determined pressure (p) occurs. Method according to Claim 2, characterized in that the hydrostatic clutch actuator ( 3 ) is switched on and off again until, at a predetermined pressure value (p), the clutch actuator ( 3 ) remains motionless. A method according to claim 1 or 2, characterized in that the fixed, by the pressure in the hydrostatically actuated coupling system ( 1 ) dependent pilot characteristic (A, B) is used. A method according to claim 6, characterized in that the pilot control characteristic (A, B) during commissioning of the hydrostatically actuated clutch system ( 1 ) once to the hydrostatically actuated coupling system ( 1 ) and over the life of the hydrostatically actuated coupling system ( 1 ) remains unchanged. Method according to one of the preceding claims, characterized in that the pressure (p) within the hydrostatically actuated coupling system ( 1 ) from a displacement of a touch point of the coupling ( 8th ) is determined. Method according to at least one of the preceding claims, characterized in that the pressure (p) is smoothed by means of a, preferably sliding, averaging. Method according to at least one of the preceding claims, characterized in that the determined pressure (p) over the actuator position (W) is corrected by a hysteresis component.

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