WO2015018408A2

WO2015018408A2 - Method for positioning a piston

Info

Publication number: WO2015018408A2
Application number: PCT/DE2014/200320
Authority: WO
Inventors: Marco Borowski; Alexander Renfer
Original assignee: Schaeffler Technologies Gmbh & Co. Kg
Priority date: 2013-08-09
Filing date: 2014-07-14
Publication date: 2015-02-12
Also published as: CN105452697B; DE112014003663A5; DE112014003663B4; WO2015018408A9; WO2015018408A3; CN105452697A; DE102014213621A1

Abstract

The invention relates to a method for controlling an actuating system of an automated clutch in a motor vehicle. The control of the actuating system is accomplished by means of a control unit. The actuating system comprises a piston, a cylinder, and a sealing ring arranged on the piston or on the cylinder in a circumferential direction. The purpose of the method is to position the piston in the cylinder in an axial direction. The cylinder and/or the piston has an opening in the respective lateral surface of the cylinder and/or of the piston, over which opening the sealing ring can travel during a piston movement in the axial direction in both directions. The method is characterised in that, during a specified standstill situation of the vehicle, the piston is moved to a parking position in the cylinder, which parking position is selected in the cylinder in such a way that the sealing ring is positioned without overlap with the opening.

Description

Method for positioning a piston

The invention relates to a method having the features according to the preamble of claim 1.

Field of application and intended use of the invention are hydrostatic actuators, in particular for clutch actuation.

The German patent application DE 10 2012 204 635 A1 discloses a control unit with a tracking function. DE 197 34 038 A1 discloses a snoop cycle in a clutch actuator with a sniffer opening and a method for learning the position of the sniffer opening.

The present invention describes the positioning of a piston in a master cylinder when the vehicle is not in operation in a clutch actuation of a clutch of a dual-clutch transmission with a hydrostatic clutch system. Hydrostatic clutch systems are designed with a clutch actuator as shown for example in Figure 1, in DE 10 2010 047 800 A1 and DE 10 2010 047 801 A1. The clutch actuator is a so-called hydrostatic clutch actuator HCA (Hydrostatic Clutch Actuator). Under such a hydrostatic actuator is an actuator with a hydrostatic transmission path, for example, a pressure line with a fluid such as hydraulic fluid to understand. The pressure in the pressure line is detected by a pressure sensor. If an associated element is to be moved by the hydrostatic actuator, hydraulic fluid is moved in the transmission path or the pressure line, caused by the piston in the master cylinder, which moves a piston in a slave cylinder coupled by the hydraulic fluid. If the element is to hold its position, the hydraulic fluid in the transmission path rests so that there is a hydrostatic state of the hydraulic fluid that gives its name to this actuator.

If the clutch system is parked in the open state (park position), ie the sniffer grooves in the piston are below the primary outer seal attached to the inner wall of the cylinder, and the temperature gradient drops to negative, ie the temperature drops from 80 ° C at -30 ° C, it comes to freezing the seal geometry. This means that at high temperatures, as they occur in the operating state, the seal is elastically flexible and lays locally in the grooves. By cooling the system down to cryogenic temperature, this condition is frozen, and when the system is actuated and the piston moves axially, the sniffer grooves are passed over by the gasket until the gasket seals At this point, the piston-cylinder-sealing system should seal, but since at low temperature, the seal is no longer very elastic, it can be the closed, smooth lateral surface of the The piston does not adapt to the same extent as at high temperatures, thus creating a gap between the seal and the piston skirt surface due to the garland shape which thus leads to leakage and thus the desired pressure can no longer be established.

In the context of this document the terms sniffing hole, Schnüffelnut, sniffing opening and opening are used essentially synonymously. A sniffer bore is usually located as a sniffer opening in the cylinder, while a sniffer groove is typically located as a sniffer opening in the piston.

The object of the present invention is to present a possibility, the fluid leakage due to the Abstellposition of the seal radially above the sniffer opening so at overlap i.e.. direct contact of seal and sniffer opening to eliminate.

This object is achieved by a method having the features according to claim 1.

The problem is thus solved by the method described below:

The invention thus provides a method for controlling an actuator of an automated clutch in a motor vehicle, wherein the control of the actuator is performed with a control unit and wherein the actuator has a piston and a cylinder and a circumferentially arranged on the piston or on the cylinder sealing ring. According to the invention, the method is provided for positioning the piston in the axial direction in the cylinder, wherein the cylinder and / or the piston has an opening in the respective lateral surface of the cylinder and / or piston, which in a piston movement in the axial direction in both directions Sealing ring can be driven over. According to the invention, it is provided that, given a predetermined standstill situation of the vehicle, the piston ben is moved to a parking position in the cylinder, wherein the parking position is selected in the cylinder such that the sealing ring is positioned without overlapping with the opening.

The respective lateral surfaces are the surface of the piston and / or the inner circumferential surface of the cylinder. Overlap free means the sealing ring and opening at the parking position have no direct contact with each other.

The inventive method therefore has the advantage that the piston is turned off during the standstill situation of the vehicle in an area of the cylinder in which the sealing ring - when it is attached to the cylinder - completely from the smooth surface of the piston and - if he on the piston is fixed - is completely surrounded by the inner circumferential surface of the cylinder, the sealing ring thus has no contact with the opening into which he could deform disadvantageously.

In a particularly preferred embodiment, it is provided that the storage position is selected such that there is no flow connection between the opening and a fluid enclosed by the piston in the cylinder volume.

In a further preferred embodiment, it is provided that the control unit has a follow-up time starting with ignition Off of the vehicle. Only after the follow-up time, the controller turns off.

In a further preferred embodiment, it is provided that the duration of the follow-up time can be predetermined.

In a further preferred embodiment, it is provided that the duration of the follow-up time is predetermined as a function of the fluid temperature of the fluid enclosed by the piston and cylinder. Instead of the fluid temperature, it is also possible to use the temperature of the actuator system or of the coupling system or of components of the actuator system or coupling system, depending on which module a temperature measurement or calculated temperature determination is available for. To determine the follow-up time, a cooling rate of the fluid or one of the mentioned modules can also be taken into account. In a further embodiment, it is provided that the duration of the follow-up time is a maximum of 30 minutes.

In a further particularly preferred embodiment it is provided that during the follow-up time, the piston is positioned such that there is a flow connection between the opening and the fluid enclosed by the piston in the cylinder volume.

In a further preferred embodiment, it is provided that, when the vehicle is unlocked, the piston is positioned such that there is a flow connection between the opening and the fluid enclosed by the piston in the cylinder volume.

In a further alternative embodiment, it is provided that upon activation of the ignition of the vehicle, the piston is positioned such that a flow connection between the opening and the fluid enclosed by the piston in the cylinder volume exists.

In a further alternative embodiment, it is provided that in a period between the unlocking of the vehicle and the activation of the ignition of the vehicle, the piston is positioned such that there is a flow connection between the opening and the fluid enclosed by the piston in the cylinder volume.

In a further particularly preferred embodiment, it is provided that the predetermined standstill situation of the vehicle is given during ignition Off of the vehicle and simultaneous non-existence of the follow-up time.

In a further preferred embodiment, it is provided that the predetermined standstill situation is given if in addition the vehicle is unlocked.

Further advantages and advantageous embodiments of the invention are the subject of the following figures and their description.

They show in detail: Figure 1 shows a schematic structure of a hydrostatic coupling system

FIG. 2 is a sectional view of a hydrostatic clutch actuator

Figure 3 Inventive Abstellposition of the piston: primary outer seal parked on "sniffing closed" position

FIG. 1 schematically shows the structure of a hydraulic coupling system 1 using the example of a hydraulic, hydrostatic clutch actuator (HCA), which is known from the prior art and shown schematically. This schematic diagram shows only the structure for operating one of the two clutches of a dual-clutch transmission, the operation of the second clutch is analog. The hydraulic clutch system 1 comprises on the encoder side 15, a control unit 2, which drives an actuator 3. In a change in position of the actuator 3 and the piston 19 in the cylinder 4 along the Aktorweges to the right, the volume of the cylinder 4 is changed, whereby a pressure P in the

Cylinder 4 is constructed, which via a pressure medium 7 via a hydraulic line 9 for

Nehmerseite 16 of the hydraulic clutch system 1 is transmitted. The hydraulic line 9 is adapted with respect to its length and shape of the installation space situation of the vehicle. On the slave side 16 causes the pressure P of the pressure means 7 in a cylinder 4 'a

Path change, which is transmitted to a clutch 8 to operate this. The pressure P in the cylinder 4 on the encoder side 15 of the hydraulic clutch system 1 can be determined by means of a first sensor 5. The first sensor 5 is preferably a pressure sensor. The distance traveled by the actuator 3 along the

Aktorweges is determined by means of a second sensor 6.

The schematic representation of Figure 1 is shown in Figure 2 and Figure 3 - in particular the cylinder-piston combination 4,19,100 with opening 18,140 concerning - shown in more detail. In Figure 1, the opening is located as a sniffer bore 18 in the cylinder 4 while in the figures 2 and 3, the opening is shown as Schnüffelnut 140 in the piston 100.

The piston 100 is not placed in software as before on the sniffer position, so not in the state "sniffing groove on, so that the seal 1 10 does not overlap with the Schnüffelnut 140 and thus not in this more or less einformt, but according to the invention in one position" Snoop Closed "parked (Figure 3) so that tion 1 10 and Schnüffelnut 140 do not overlap and the seal 1 10 so rests only on the smooth piston surface, and thus is not in contact with the Schnüffelnut 140.

The snoop position, ie the state "sniff opening on has the purpose that a pressure change in the master cylinder due to temperature changes by means of a surge tank 17 can be compensated. In order to prevent that e.g. After a long drive on the highway in the direction of higher temperatures (postheating) as well as underpressure or overpressure during cooling, a variable overrun time of the control device 2 should be enabled after ignition off (for example up to 15 minutes).

During this time, the piston 100 should still remain at the sniffer position, ie in the state "sniff opening remaining and only after this time has elapsed, move to the position" sniffer opening closed. "In order to further avoid an unintentional torque on the clutch when starting the engine, it should This can be done as with other systems today from the time when the vehicle is unlocked, but at the latest at "ignition on" (terminal 15).

In terms of safety, a still existing pressure is monitored by means of pressure sensor 5.

Hydrostatic actuators as they are used for clutch actuation in the parking position - also referred to as Abstellposition - on the piston 100 sniffer grooves 140 to compensate for the volume compensation in the hydraulic circuit, for example, compensate for temperature fluctuations. Due to the elasticity of the sealing rings 1 10, the sealing ring sets 1 10 when it is a long time radially over the Schnüffelnut 140 at high temperatures in the Schnüffelnut 140. By cooling to low temperatures, this loses flexibility and becomes inflexible. If the piston 100 is now moved axially to build up the pressure and passes over the sniffer grooves 140, pressure can be built up from the closed lateral surface. Due to the significantly reduced flexibility of the sealing ring retains the previously imposed form, which has formed in the parking position at high temperatures. As a result, the sealing function is impaired on the closed lateral surface and leads to leakage.

By a software change is now no longer as before the seal 1 10 on the Schnüffelnuten 140 in the piston 100 or the Schnüffelbohrungen 18 in the cylinder 4, but on the smooth shell surface of piston 100 or cylinder 4 without the seal 1 10 has direct contact with the sniffer opening 18,140, as given in the position "sniffer opening closed." In order to further enable the volume compensation is on the one hand, a follow-up time of the control unit integrated and on the other hand given the command to drive in position "open sniffer opening" as soon as the vehicle is unlocked but at the latest when the ignition is activated.

LIST OF REFERENCE NUMBERS

Hydraulic coupling system

control unit

actuator

, 4 'cylinder

first sensor

second sensor

lever

clutch

hydraulic line

0 way-pressure characteristic

5 donor side

6 taker side

7 expansion tank

8 sniff opening

9 pistons 00 piston

10 primary outer seal

20 secondary outer seal

30 primary inner seal

40 sniff opening

Claims

claims

1 . Method for controlling an actuator system (3) of an automated clutch (1) in a motor vehicle, wherein the control of the actuator system (3) with a control unit (2) and wherein the actuator (3) comprises a piston (19,100) and a cylinder (4 ) and a circumferentially on the piston (19,100) or on the cylinder (4) arranged sealing ring (1 10) for positioning the piston (19,100) in the axial direction in the cylinder (4), wherein the cylinder (4) and / or the piston (19,100) has an opening (18,140) in the respective lateral surface of the cylinder (4) and / or piston (19,100), which can be run over during a piston movement in the axial direction in both directions by the sealing ring (1 10), characterized in that, given a predetermined standstill situation of the vehicle, the piston (19, 100) is moved to a parking position in the cylinder (4), wherein the parking position is selected in the cylinder (4) such that the sealing ring (110) overlaps with the opening (18,140) is positioned.

2. The method according to claim 1, characterized in that the storage position is selected such that no flow connection between the opening (18,140) and one of the piston (19,100) enclosed fluid (7) in the cylinder volume.

3. The method according to any one of the preceding claims, characterized in that the control unit (2) has a follow-up time starting with ignition Off of the vehicle.

4. The method according to any one of the preceding claims, characterized in that the duration of the follow-up time can be predetermined.

5. The method according to any one of the preceding claims, characterized in that the duration of the follow-up time in dependence on the fluid temperature of the piston (19,100) and cylinder (4) enclosed fluid (7) is specified.

6. The method according to any one of the preceding claims 1 to 5, characterized in that the duration of the follow-up time is a maximum of 30 minutes.

7. The method according to any one of the preceding claims, characterized in that during the follow-up time of the piston (19,100) is positioned such that a Strö- mung connection between the opening (18,140) and the piston (19,100) enclosed fluid (7) in the cylinder volume consists.

8. The method according to any one of the preceding claims, characterized in that when unlocking the vehicle, the piston (19,100) is positioned such that a flow connection between the opening (18,140) and the piston (19,100) enclosed fluid (7) in the cylinder volume ,

9. The method according to any one of the preceding claims 1 to 7, characterized in that when activating the ignition of the vehicle, the piston (19,100) is positioned such that a flow connection between the opening (18,140) and the piston (19,100) trapped fluid ( 7) in the cylinder volume.

10. The method according to any one of the preceding claims 1 to 7, characterized in that in a period between the unlocking of the vehicle and the activation of the ignition of the vehicle, the piston (19,100) is positioned such that a flow connection between the opening (18,140) and consists of the piston (19,100) enclosed fluid (7) in the cylinder volume.

1 1. Method according to one of the preceding claims, characterized in that the predetermined standstill situation of the vehicle during ignition Off of the vehicle and simultaneous absence of the follow-up time is given.

12. The method of claim 1 1, characterized in that the predetermined standstill situation is given if in addition the vehicle is unlocked.