DE112015003766B4 - Method for protecting a clutch actuator of a clutch actuation system, preferably for a motor vehicle - Google Patents

Abstract

Method for protecting a clutch actuator system for a clutch actuation system, preferably for a motor vehicle, which controls a self-closing clutch (4) by electrically adjusting a first piston (18) of a master cylinder (13) of the clutch actuator system, whereby via a hydrostatic path (14). Actuation of the clutch (4) a second piston (16) of a slave cylinder (15) is moved, a maximum travel path of the second piston (16) being limited by a stop, a non-permanent stop being used, the stop being considered to be actuated is when the second piston (16) has covered a stop path which is reduced by a predetermined distance value compared to the mechanical stop, a maximum position of a hydrostatic clutch actuator (12) being defined depending on the stop path traveled, the clutch actuator system being up to one successful detection of the stop path of the second piston (16), wherein upon successful detection of the stop path of the second piston, a first position of the hydrostatic clutch actuator (12), which is smaller than the maximum position, is considered to have been reached, at which the clutch (4 ) is safely opened, the maximum position of the hydrostatic clutch actuator (12) being determined depending on the tolerances of a displacement sensor (25) which detects the stop path of the second piston (16) of the slave cylinder (15), the maximum position of the hydrostatic clutch actuator being set (12) and/or the non-durable stop during a band end test of the production of a transmission (9) comprising the clutch (4), characterized in that a touch point adaptation is carried out as part of the band end test, with a readiness point of the hydrostatic clutch actuator (12) is defined, in which the clutch (4) is considered to be open.

Description

The invention relates to a method for protecting a clutch actuator of a clutch actuation system, preferably for a motor vehicle, which controls a self-closing clutch by electrically adjusting a first piston of a master cylinder of the clutch actuator, whereby a second piston of a slave cylinder moves over a hydrostatic path to actuate the clutch and a maximum travel path of the second piston is limited by a stop.

DE 10 2010 003 499 A1 discloses a method for bleeding a hydraulic actuator for a vehicle clutch.

DE 10 2014 213 620 A1 discloses a method for determining a position of a linearly moving actuator gear in a clutch actuator system of a motor vehicle.

From the DE 10 2012 218 255 A1 a method for controlling a clutch with a hydrostatic actuator is known, which comprises a threaded spindle which is rotated in order to move a piston of a master cylinder in the axial direction, a path traveled by the piston being determined directly or indirectly with the aid of a sensor device.

If self-closing clutches, also known as non-actuated closed clutches, are used in combination with a hydrostatic clutch actuator, the clutch is actuated via a hydrostatic path. The piston of a master cylinder is driven by an electric motor and a second piston in a slave cylinder is actuated via hydraulic fluid in the system. The second piston of the slave cylinder acts on the lever spring tips, which then lift off from a clutch disc when a clutch plate is actuated and thus interrupt the transmission of clutch torque via the clutch. When not actuated, the preloaded lever spring closes the clutch.

In contrast to conventional clutches, which are actuated by a clutch pedal, the ratio between the measurable travel of the hydrostatic clutch actuator and the travel of the piston of the slave cylinder is very small. Errors in the positioning of the hydrostatic clutch actuator are transmitted directly to the piston of the slave cylinder. This situation is further aggravated by the fact that position detection of the hydrostatic clutch actuator inherently has very large tolerances that are significantly larger than in a manually operated system. A large part of the tolerances of the hydrostatic actuator relate to the accuracy of the installation position of an absolute position sensor.

With a defined position of the hydrostatic clutch actuator, there is a large inaccuracy in the position of the piston of the slave cylinder, as shown in 3 is shown. In order to open the clutch safely, a specific path of the hydrostatic clutch actuator (HCA) must be approached, taking into account all possible tolerances that occur due to the geometry of the individual components of the clutch actuator, such as piston surface tolerances, friction scatter, absolute value sensor errors of the hydrostatic actuator, new condition and others become. How out 3 As can be seen, with a stroke of the slave cylinder piston of, for example, 6.3 mm, the position of the hydrostatic clutch actuator (HCA) of 13.3 mm must be approached. However, if the hydrostatic clutch actuator (HCA) covers a distance of 13.3 mm, an adjustment distance in the slave cylinder of 10.8 mm can result. However, due to the installation space, the maximum stroke of the slave cylinder is limited to 9.6 mm. However, in order to move the clutch into the safe opening position, the maximum permitted travel of the slave cylinder piston can be exceeded by up to a distance of 10.8 mm due to the tolerance spread due to the travel of the hydraulic clutch actuator (HCA). If the maximum permissible stroke of the slave cylinder is exceeded, hydraulic fluid will leak and the system will be destroyed, making clutch actuation no longer possible.

The invention is based on the object of specifying a method for protecting the clutch actuator system, in which clutch components remain undamaged despite tolerances, component scatter and only a limited number of stop detections.

According to the invention the object is achieved by a method with the features according to claim 1.

According to the invention, the object is achieved in that a non-permanent stop is used, the stop being considered to be actuated when the second piston of the slave cylinder has covered a stop path which is reduced by a predetermined distance value compared to the stop, depending on a maximum position of a hydrostatic clutch actuator is defined based on the stop path traveled. A non-permanent stop is to be understood as meaning a stop that is not designed for the entire service life of the slave cylinder. This ensures that the stop in the slave cylinder is not actuated by most systems that include the clutch and hydrostatic clutch actuator. The lack of actuation reliably prevents the slave cylinder from being damaged. Determining the maximum position of the hydrostatic clutch actuator depending on the non-permanent stop ensures that the clutch is safely opened in this position of the slave cylinder and therefore no clutch torque is transmitted.

According to the invention, the clutch actuator is actuated until the stop travel of the second piston is successfully detected, whereby upon successful detection of the stop travel of the second piston, a first position of the hydrostatic clutch actuator, which is smaller than the maximum position, is considered to have been reached, at which the clutch is safely opened is. Since in this case the maximum position of the hydrostatic clutch actuator is certainly not approached, forces that actuate the slave cylinder over the specified maximum stroke and thus destroy the system are also eliminated.

In one embodiment, if the stop travel of the second piston of the slave cylinder is not detected, the maximum position of the hydrostatic clutch actuator is reduced by a predetermined value. This ensures that the clutch is always safely opened due to the position that the hydrostatic clutch actuator has assumed and that the maximum stroke of the slave cylinder is not exceeded.

According to the invention, the maximum position of the hydrostatic clutch actuator is determined depending on the tolerances of a displacement sensor that detects the stop travel of the second piston of the slave cylinder. Not only the tolerances of the individual system units are taken into account, but also those of the measuring sensors, so that incorrect actuation of the clutch actuators is reliably prevented.

According to the invention, the maximum position of the hydrostatic clutch actuator and/or the non-permanent stop is adjusted during a belt end test of the production of a transmission comprising the clutch. During the belt end test, the clutch system learns based on the proposed method both the maximum position of the hydrostatic clutch actuator and the position of the non-durable stop, which are then used in the operation of the transmission in the motor vehicle over its service life.

According to the invention, a touch point adaptation is carried out as part of the belt end test, defining a ready point of the hydrostatic clutch actuator at which the clutch is considered to be open. Due to this setting, the routines that are carried out during the end-of-line check can be processed reliably.

Advantageously, the readiness point of the hydrostatic clutch actuator is smaller than its maximum position. The ready point, which represents the touch point plus a tolerance of x mm, indicates that the clutch is defined as open for further operation. Since this touch point and thus the ready point represents an important parameter when controlling the clutch during operation of the motor vehicle, it must not be above the maximum position of the hydrostatic clutch actuator in order to prevent damage to the clutch actuator system.

In one variant, a separating clutch of a drive train of a hybrid vehicle is used as a clutch. Errors that can be transmitted to the piston of the slave cylinder when positioning the hydrostatic clutch actuator are minimized.

The invention allows numerous embodiments. One of them will be explained in more detail using the figures shown in the drawing.

• 1 Prinzipdarstellung eines Antriebsstranges eines Hybridfahrzeuges.
• 2 Prinzipdarstellung eines Kupplungsbetätigungssystems in dem Hybridfahrzeug,
• 3 eine Darstellung der Übersetzungsstreuung einer Kupplung mit einem hydrostatischen Kupplungsaktor nach dem Stand der Technik.

Show it:

• 1 Schematic diagram of a drive train of a hybrid vehicle.
• 2 Principle representation of a clutch actuation system in the hybrid vehicle,
• 3 a representation of the translation spread of a clutch with a hydrostatic clutch actuator according to the prior art.

The basic representation of a drive train 1 of a hybrid vehicle is in 1 shown. This drive train 1 includes an internal combustion engine 2 and an electric motor 3. A separating clutch 4 is arranged between the internal combustion engine 2 and the electric motor 3 directly behind the internal combustion engine 2. Internal combustion engine 2 and separating clutch 4 are connected to one another via a crankshaft 5. The electric motor 3 has a rotatable rotor 6 and a fixed stator 7. The output shaft 8 of the separating clutch 4 is connected to a gear 9, which contains a coupling element (not shown), for example a second clutch or a torque converter, which is connected between the electric motor gate 3 and the gearbox 9 is arranged. The transmission 9 transmits the torque generated by the internal combustion engine 2 and/or the electric motor 3 to the drive wheels 10 of the hybrid vehicle. The separating clutch 4 and the transmission 9 form a transmission system 11, the separating clutch 4 being controlled by a hydrostatic clutch actuator 12.

In 2 the hydrostatic clutch actuator 12 for actuating the separating clutch 4 is shown in simplified form. The hydrostatic clutch actuator 12 includes a master cylinder 13, which is connected to a slave cylinder 15 via a hydraulic line 14, also known as a pressure line. In the slave cylinder 15, a slave piston 16 is mounted axially movably, which actuates the separating clutch 4 with the interposition of a release bearing 17. A master piston 18 is mounted in an axially movable manner in the master cylinder 13. A piston rod 19 extends from the master piston 18 and can be moved in translation along the longitudinal extent of the master cylinder 13 together with the master piston 18. The piston rod 18 of the master cylinder 13 is coupled to an electromotive actuator 21 via a threaded spindle 20. The electromotive actuator 21 comprises an electric motor 22 and an evaluation unit 23. The threaded spindle 20 converts a rotary movement of the electric motor 22 into a longitudinal movement of the piston rod 19 or the master piston 18. A first displacement sensor 24 is arranged parallel to the master cylinder 13, while a second displacement sensor 25 detects the displacement of the slave piston 16 on the slave cylinder 15.

Furthermore, it is assumed that the separating clutch 4 is a clutch that is closed when not actuated (self-closing clutch). When producing such a transmission system 11, which includes the separating clutch 4, the transmission system 11 is subjected to an end-of-band test, at which stops for both the slave piston 16 of the slave cylinder 15 and the maximum distances that the hydrostatic clutch actuator 12 is allowed to travel are learned in order to thus preventing destruction of the clutch actuators. An actuation stroke is carried out on the transmission system 11 to be tested on a test bench, with the hydrostatic clutch actuator 12 assuming a predetermined position due to the movement of the master piston 18 of the master cylinder 13, which is transmitted via the hydraulic fluid to the slave piston 16 of the slave cylinder 15, whereby this also occupies a corresponding position. Due to the tolerances of the different transmission systems 21, it will occur that part of the transmission systems 21 reaches the stop, while another part of the transmission systems 21 does not reach this stop. In order to ensure that destruction of the components of the transmission system 21 is prevented even with this wide spread, two strategies are distinguished. In both strategies, a non-durable mechanical stop is used, which means that this stop is mechanically designed in such a way that it can only survive a limited number of actuation strokes. However, the non-durable stop is not able to withstand the million operations of the transmission system 21, which are necessary over its service life. In the case of the non-durable stop, the stop path of the slave piston 16 of the slave cylinder 15 to be detected is adjusted so that the stop is considered to have been reached when a predetermined distance value, by which the stop position is reduced, is reached by the second slave piston 16 of the slave cylinder 15 , which is detected by means of the displacement sensor system 25.

In the event that this predetermined distance value is successfully detected by the displacement sensor 25 when the transmission system 21 is actuated, it is assumed that the state of the separating clutch 4 is guaranteed to be safely opened with this actuation stroke. This means that the master cylinder 13 of the hydrostatic clutch actuator 12 assumes a position in which the clutch 4 is reliably opened by the slave cylinder 15 without damaging it. This consideration assumes that the stop forces and the plate spring travel that actuate the separating clutch 4 are within predetermined tolerances. This interpretation results, for example, in a minimum distance value for a safely opened separating clutch 4 of, for example, 1 mm, which means that the stop path to be detected, which the second slave piston 16 of the slave cylinder 15 covers during an actuation stroke, ends 1 mm before the actual mechanical stop .

To define the maximum position of the hydrostatic clutch actuator 12, the tolerances of the displacement sensor 24, which detects the displacement of the master piston 18 of the master cylinder 13, are also taken into account. This maximum position corresponds to a stop path of the slave cylinder 15, which is 0.5 mm smaller than the position of the stop of the slave cylinder 15. This ensures that the self-closing separating clutch 4 opens sufficiently with this defined path of the hydrostatic clutch actuator 12 so that the band end- Routines can be carried out. At the same time, there is the possibility that the stop of the slave piston can be approached once during a new commissioning, for example in the event of service when a component is replaced.

The second possibility of setting the maximum positions of the hydrostatic clutch actuator 12 and the stop is considered under the condition that the slave piston 16 of the slave cylinder 15 has not carried out the defined stop path, which is why this cannot be detected. It is assumed that the stop forces are OK, but not the plate spring travel. In this case, each transmission system 12 on the test bench is subjected to an actuation stroke, in which it is assumed that the hydrostatic clutch actuator 12 safely opens the separating clutch 4 plus covers a defined additional path, in which the tolerances of the displacement sensor system 24 are again taken into account. In transmission systems 21 that do not cover the specified stop travel, the maximum position of the hydrostatic clutch actuator 12 is limited to the actuating stroke traveled by 0.5 mm.

In both options explained, the separating clutch 4 is actuated sufficiently, which is why the requirement of the stop and the permitted plate spring travel are taken into account. The maximum position of the hydrostatic clutch actuator 12 is now learned in the same way as the stop and is stored in the transmission system 21 and used when starting the separating clutch 4 during operation in the motor vehicle, with damage or destruction of the clutch actuator system reliably preventing the actuation of the slave cylinder 16 over its service life becomes.

Starting from the maximum position of the hydrostatic clutch actuator 12 and the learned stop path, a touch point adaptation is carried out during the belt end test, in which a readiness point is defined depending on the detected touch point at which the separating clutch 4 begins to transmit a clutch torque, at which the Separating clutch 4 is reliably open and therefore does not transmit any clutch torque. The ready point is made up of the touch point plus x mm.

By using a non-permanent stop in the separating clutch 4 or in the slave cylinder 15, a control strategy for the separating clutch 4 is selected in which the stop is not detected every time it is actuated, but on the one hand the clutch actuator is still protected from damage and on the other hand the separating clutch 4 is sufficiently pressed on .

Reference symbol list

1

Drivetrain

2

Internal combustion engine

3

Electric motor

4

Separating clutch

5

crankshaft

6

rotor

7

stator

8th

output shaft

9

transmission

10

drive wheels

11

Transmission system

12

hydrostatic clutch actuator

13

Master cylinder

14

Hydraulic line

15

slave cylinder

16

slave piston

17

release bearing

18

Master piston

19

Piston rod

20

threaded spindle

21

electric motor actuator

22

Electric motor

23

Evaluation unit

24

Distance sensors

25

Distance sensors

Claims (4)

Method for protecting a clutch actuator system for a clutch actuation system, preferably for a motor vehicle, which controls a self-closing clutch (4) by electrically adjusting a first piston (18) of a master cylinder (13) of the clutch actuator system, whereby via a hydrostatic path (14). Actuation of the clutch (4) a second piston (16) of a slave cylinder (15) is moved, a maximum travel path of the second piston (16) being limited by a stop, a non-permanent stop being used, the stop being considered to be actuated is when the second piston (16) has covered a stop path which is reduced by a predetermined distance value compared to the mechanical stop, a maximum position of a hydrostatic clutch actuator (12) being defined depending on the stop path traveled, the clutch actuator system being up to one successful detection of the stop path of the second piston (16) is actuated, with successful detection of the stop path of the second piston a first Position of the hydrostatic clutch actuator (12), which is smaller than the maximum position, is considered to have been reached, at which the clutch (4) is safely opened, the determination of the maximum position of the hydrostatic clutch actuator (12) depending on tolerances, the stop path of the second piston (16) of the slave cylinder (15) detecting the displacement sensor (25), the maximum position of the hydrostatic clutch actuator (12) and/or the non-permanent stop being set during a belt end test of the production of a clutch (4). comprehensive transmission (9), characterized in that a touch point adaptation is carried out as part of the belt end test, a readiness point of the hydrostatic clutch actuator (12) being defined, at which the clutch (4) is considered to be open. Procedure according to Claim 1 , characterized in that if the stop travel of the second piston (16) of the slave cylinder (15) is not detected, the maximum position of the hydrostatic clutch actuator (12) is reduced by a predetermined value. Procedure according to Claim 1 or 2 , characterized in that the readiness point of the hydrostatic clutch actuator (12) is smaller than its maximum position. Method according to at least one of the preceding claims, characterized in that a separating clutch (4) of a drive train (1) of a hybrid vehicle is used as the clutch.

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