DE102010039401A1 - Coupling system and method for controlling the same - Google Patents

Abstract

The invention relates to a clutch system with a clutch, a hydraulic system consisting of an actuation unit, a hydraulic line and an electrohydraulic actuator, and a control unit for controlling the actuator, the control unit controlling the actuator in such a way that a constant Pressure is applied.

Description

State of the art

The DE 10 2007 003 902 A1 describes an apparatus and a method for controlling a coupling system, wherein on an actuating unit a the adjustment of the coupling part delimiting mechanical stop is formed and wherein means are provided which monitor the pressure in the hydraulic system or a drive signal of the actuator.

In hybrid drives, it may be necessary to decouple the engine from the drive train can. This makes it possible for a vehicle to drive only with electric drive, thus producing less emissions on average. For the decoupling of the internal combustion engine automated couplings can be used.

In automated clutch systems in vehicles with hybrid drives, it is important to control the path on the release system and the clutch torque as accurately as possible to ensure a desired ride comfort.

The path on the release system is adjusted in such systems by a hydraulic line with an electromechanical actuator. Since, for technical reasons, only the position of the actuator is measured, it will be the case that by changing the hydraulic pressure / volume, for example by temperature changes or small leaks, with the clutch open, the position of the releaser changes and this shift a disturbing effect Clutch closure caused.

Disclosure of the invention

It has been found that in the coupling systems known from the prior art, faults, such as leaks, air inclusions, elasticity changes or temperature fluctuations and other influences on the hydraulic connection between the position detection in the actuator and the hydraulic actuating unit of the clutch can lead to the indirectly detected by means of the path detection of Aktuatorstellglieds position of the adjustable coupling part does not correspond to the actual position of the coupling part. This can result in that on the adjustable coupling part of the hydraulic actuating unit of the clutch is not that path is set, which is required to open or to set a predetermined torque of the clutch, whereby a clutch, for example, drags more often than necessary and can be destroyed quickly. In addition, the coupling can be damaged by excessive release distances.

These disadvantages are eliminated or at least reduced by the subject matter of the respective independent claims. Further advantageous embodiments are described in the respective dependent claims.

In general, a clutch system according to the invention comprises a clutch, a hydraulic system and a control unit. The hydraulic system, in turn, includes an actuator unit for connecting and disconnecting a power transmission path between a clutch input side and a clutch output side, a hydraulic line, and an electro-hydraulic actuator connected to the actuator via the hydraulic line. The clutch system further includes a pressure sensor for detecting the pressure in the hydraulic system and a position sensor for detecting the position of the actuator.

The control unit can detect the change in the pressure in the hydraulic system via the pressure sensor and control the actuator such that a certain pressure is maintained in the hydraulic system.

According to one embodiment of the invention, the control unit may be configured such that upon a change in the position of the actuator due to a change in the pressure in the hydraulic system, a correction value for the position of the actuator is generated. This correction value can be stored, so that the control unit can take into account the correction value in the activation of the actuator in a subsequent coupling process.

In this way, it can be ensured that changes in the volume of the hydraulic fluid are detected by the control unit and in a dome operation can be ensured that the desired accuracy of the clutch is maintained.

A clutch system according to the invention can be used according to an embodiment of the invention, in particular in a hybrid drive train between an internal combustion engine and an electric motor / generator. In such use, the compensation of changes in the volume or the pressure in the hydraulic system will be particularly advantageous, since the coupling operations occur at greater intervals.

According to one aspect of the invention, a method of pressure-lock in a hydraulic system of a clutch system is proposed, which method can be used in hydraulic clutch systems with pressure sensors to compensate for the pressure / volume change of a hydraulic fluid. The advantage of the method is that the compensation is calculated on the basis of the measured physical quantity, that is the pressure. This improves the accuracy of the clutch and ride comfort.

The method according to the invention for controlling a clutch system comprises the steps of: detecting a first pressure in the hydraulic system, detecting a first position of an electro-hydraulic actuator of the hydraulic system, detecting a second pressure in the hydraulic system, the second pressure at a later Timing is detected as the first pressure, comparing the first pressure with the second pressure, and when the second pressure deviates from the first pressure by a predetermined amount, changing the position of the actuator from the first position to a second position, so that the deviation is compensated.

In this way, despite changes in the hydraulic fluid, the pressure in the hydraulic system can be kept almost constant, whereby the actuated by the hydraulic system clutch with high accuracy maintains a certain operating condition.

It is noted that the second pressure and the second position may again be regarded as initial values, that is to say as first pressure and first position, so that the method can be repeated continuously.

A subsequent dome operation can be performed on the basis of the second position of the actuator according to an embodiment of the invention, when this second position value is stored in the control unit.

Alternatively, a subsequent dome operation may be performed based on a correction value, wherein the correction value for the position of the actuator may be determined based on the first detected position and the second detected position.

According to another aspect of the invention, there is provided a computer program that performs all steps of a method when running on a control unit of a clutch system as described above. A corresponding computer program is preferably loaded into a main memory of a control unit. The control unit or a data processor is thus equipped to carry out the method according to the invention.

Furthermore, the invention also relates to a computer-readable medium, such as a CD-ROM, in which the computer program can be stored. However, the computer program may also be provided over a network, such as the Internet, and may be downloaded into the memory of the controller from that network.

It is noted that embodiments of the invention will be described with reference to different items. In particular, some embodiments will be described in terms of device claims and other embodiments with respect to method claims. However, one skilled in the art from the above and following description will recognize, in addition to any combination of features associated with a type of item, any combination of features described with respect to different items. All this is part of the overall disclosure of the application.

Aspects described above and other aspects, features and advantages of the invention may also be had from the examples of embodiments which will be described in the following with reference to the attached drawings. It is noted that the invention is not limited to these embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

1 is a schematic representation of a coupling system according to the invention.

2 is a schematic representation of a coupling system according to the invention in a drive train of a vehicle.

3 Figure 3 is a schematic representation of the flow of pressure in the hydraulic system and the travel of the actuator over time.

4 is a pressure-distance clutch characteristic.

5 is a flowchart for schematically illustrating the method according to the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

1 shows a coupling system 100 with a clutch 10 , a hydraulic system 20 and a control unit 30 , The coupling 10 has a clutch input side 12 and a Clutch output side 14 on, which are generally formed as discs which bear against each other in the closed state of the clutch and are pulled away from each other in the open state of the clutch, so that a power transmission via the clutch 10 away is possible only when closed. Furthermore, the clutch has 10 a plate spring 16 which can generate a pressing force for pressing the clutch disks of the clutch input side against the disk of the clutch output side 14 ,

The hydraulic system 20 has a slave cylinder 22 that is a clutch release, an electrohydraulic actuator 24 as well as a hydraulic line 26 on. About an adjustment of the piston of the electro-hydraulic actuator 24 is the hydraulic fluid through the hydraulic line 26 to the slave cylinder 22 moved towards or away from it, leaving the slave cylinder 22 according to a movement of the actuator 24 moves and thus the clutch 10 can be operated.

On the hydraulic system 20 on the one hand is a pressure sensor 27 provided in 1 is arranged on the cylinder of the actuator. It is noted that the pressure sensor may be provided anywhere on the hydraulic system. Further, on the actuator 24 a position sensor 28 provided for detecting the position of the actuator. The pressure sensor 27 and the position sensor 28 are with the control unit 30 connected.

Furthermore, in 1 a data store 32 shown with the control unit 30 connected, and which offers the possibility of detected values of both the pressure sensor 27 as well as the position sensor 28 to store and at a later date, for example, in the form of a correction value for a control of the actuator to make available again.

2 shows a schematic representation of a drive train of a vehicle. In 2 is a coupling system 100 between an internal combustion engine 200 and an electric motor / generator 300 arranged, being following the electric motor / generator 300 the drive train to a driven axle 400 a vehicle is continued.

When the clutch of the clutch system 100 in the open state, the internal combustion engine can 200 from the electric motor / generator 300 be disconnected so that the drive axle 400 only from the electric motor 300 is driven. Once the clutch of the clutch system 100 When closed, the internal combustion engine can 200 the electric motor / generator 300 actively rotate so that it can generate electricity as a generator. The drive axle 400 would in this case essentially from the internal combustion engine 200 driven.

In 3 the sequence of a pressure control is shown. Shortly after the clutch opening, the operating point P / V _{set is set} with a ramp. Thus, the operating point is in the middle of the hysteresis and even small volume changes can be detected by the pressure signal. Due to small leaks or temperature influences, the pressure level in the system slowly changes while the position of the actuator remains the same, ie, if the value of S remains the same, it increases 3 the value of P from the value P _set of at. As soon as the pressure deviation from the operating point reaches a threshold value P +, the pressure control is activated. It would be possible to compensate for the pressure deviation by a PI control. If the pressure signal does not have sufficient resolution, a simple gradient algorithm can be used. In this case, if the pressure deviates, the position of the actuator is corrected with a value S-corrected. By the correction of the actuator, the pressure P is set back to the value P _setpoint .

4 shows a pressure-way clutch characteristic. As long as the operating point P / V _target is located within the hysteresis, the small volume changes of the hydraulic fluid will affect the pressure level in the system until the operating point has reached the lower or upper Hystereseachse (V +, V-). The object of the method according to the invention is to keep the pressure in the system at a constant level within the hysteresis with the actuator. The positional deviation of the actuator by the pressure control is a path compensation, which can be considered in subsequent coupling operations.

5 FIG. 11 is a flowchart showing in principle the steps of a method of controlling a clutch system. It is noted that the described steps are main steps, which main steps can be differentiated and subdivided. In addition, further substeps may be provided between the main steps. Therefore, a sub-step is only mentioned if this step is important for understanding the principle of the method according to the invention.

In step S1, a first pressure in the hydraulic system is detected.

In step S2, a first position of an electro-hydraulic actuator of the hydraulic system is detected.

In step S3, a second pressure in the hydraulic system is detected, wherein the second pressure is detected at a later time than the first pressure.

In step S4, the first pressure is compared with the second pressure.

Following the comparison, a query is made as to whether the second pressure deviates a predetermined amount from the first pressure. If this query is to be answered with No N, a pressure in the hydraulic system is again detected (a second pressure according to step S3). If the query is to be answered with Yes Y, the position of the actuator is changed from a first position to a second position in step S5, so that the deviation is compensated.

Usually, following step S5, that is to say after a change in the position of the actuator, a first pressure in the hydraulic system is detected again in step S1.

Furthermore, in 5 a step S10 is shown, which indicates an actuation of the clutch. As soon as the clutch is returned to the previous state following an actuation of the clutch in step S20, the detected position of the electrohydraulic actuator (from step S2) can be taken into account in this reset, which is described in FIG 5 is indicated by the dashed arrow between S2 and S20.

While the invention has been illustrated and described in detail in the drawings and the foregoing description, such illustrations and descriptions are to be considered illustrative or exemplary only and not restrictive. The invention is not limited to the disclosed embodiments. Other variations of the disclosed embodiments may be understood and accomplished by one of ordinary skill in the art of practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" does not exclude a plurality.

The mere fact that individual features are mentioned in different dependent claims is not intended to mean that a combination of these features can not be used to advantage. The reference numerals in the claims are not intended to limit the scope thereof.

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 102007003902 A1 [0001]

Claims (10)

Coupling system ( 100 ) comprising: a coupling ( 10 ), a hydraulic system ( 20 ) with an actuating unit ( 22 ) for connecting and disconnecting a power transmission path between a clutch input side ( 12 ) and a coupling output side ( 14 ), and an electro-hydraulic actuator ( 24 ), which via a hydraulic line ( 26 ) with the operating unit ( 22 ), and a control unit ( 30 ) for controlling the actuator, characterized in that the coupling system further comprises a pressure sensor ( 27 ) for detecting the pressure in the hydraulic system ( 20 ) and a position sensor ( 28 ) for detecting the position of the actuator, wherein the control unit controls the actuator such that in the hydraulic system is applied a constant pressure. Coupling system according to claim 1, wherein the control unit ( 30 ) is set up such that upon a change in the position of the actuator ( 24 ) due to a change in pressure in the hydraulic system ( 20 ) a correction value for the position of the actuator is generated. Coupling system according to claim 2, wherein the control unit ( 30 ) further a memory ( 32 ) for storing the correction value, wherein the control unit is set up such that the correction value is taken into account in a subsequent coupling process. Use of a coupling system ( 100 ) according to one of claims 1-3 in a hybrid drive train between an internal combustion engine ( 200 ) and an electric motor / generator ( 300 ). Method for controlling a coupling system ( 100 ) with a coupling ( 10 ), a hydraulic system ( 20 ) for actuating the clutch and a control unit ( 30 ), the method comprising the steps of: detecting a first pressure in the hydraulic system, detecting a first position of an electrohydraulic actuator of the hydraulic system, detecting a second pressure in the hydraulic system, wherein the second pressure is detected at a later time than that first pressure, comparing the first pressure with the second pressure, when the second pressure deviates from the first pressure by a predetermined amount, changing the position of the actuator from the first position to a second position, so that the deviation is compensated. The method of claim 5, further comprising the step of: Storing the second position of the actuator, wherein a subsequent dome operation on the basis of the second position of the actuator is feasible. The method of claim 5 or 6, further comprising the step of: Calculating a correction value for the position of the actuator on the basis of the first position and the second position, wherein a subsequent coupling process based on the correction value is feasible. The method of claim 5, wherein the steps of the method are repeated so that a pressure change in the hydraulic system is continuously compensated. A computer program that performs all the steps of a method according to any of claims 5-8 when running on a control unit of a clutch system according to any one of claims 1-3. Computer program product with program code stored on a machine-readable carrier for carrying out the method according to any one of claims 5-8, when the program is executed on a control unit according to one of claims 1-3.

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