DE102020201074A1 - Method for controlling an actuator for operating a parking lock in a motor vehicle transmission - Google Patents

Abstract

The invention relates to a method for controlling a hydraulically actuated actuator (10) of a parking lock system with a transmission-side parking lock (6) for locking a motor vehicle (1), in which a piston (11) of the actuator (10) is used to disengage the parking lock (6). can be acted upon by clutch pressure of a clutch (5) closed in the gear (4). The piston (11) can be mechanically locked both in a piston position (E) assigned to the engaged state of the parking lock (6) and in a piston position (A) assigned to the disengaged state of the parking lock (6). It is proposed that a defect detected in the parking lock system when the parking lock (6) is disengaged and which could lead to unwanted engagement of the parking lock (6) leads to the following procedural steps: a driver of the motor vehicle (1) is warned; (11) is released; • When the defect is detected in a gear in which the clutch (5) supplying the actuator (10) with clutch pressure is switched on, the clutch pressure is brought to a predefined maximum value, but when the defect is detected in a gear , in which the clutch (5) supplying the actuator (10) with clutch pressure is switched off, the frictional connection in the transmission (4) is interrupted and the clutch pressure of this clutch (5) is then brought to a predefined maximum value; in the transmission (4) only one gear is permitted in which the clutch (5) supplying the actuator (10) with clutch pressure remains engaged.

Description

The invention relates to a method for controlling an actuator for actuating a parking lock in a motor vehicle transmission, according to the preamble of claim 1.

The use of parking locks in motor vehicle transmissions is known from the prior art. The parking lock is used to prevent the motor vehicle from unintentionally rolling away when it is actuated. The parking lock is often designed in such a way that in the actuated state in its locked position it prevents an output shaft of the transmission from rotating and thus the motor vehicle from rolling away.

Also known from the prior art are actuating devices for engaging and disengaging the parking lock using a hydraulically controllable actuator, the hydraulic supply of which is part of a transmission hydraulics. Here, it is usually provided that a piston of the parking lock actuator arranged axially displaceably in a cylinder cavity is subjected to pressure in order to bring the parking lock out of its locking position, against the spring force of an insert spring provided for engaging the parking lock.

From the DE 10 2017 211 025 A1 a generic hydraulically controllable actuator for actuating a transmission parking lock is known, the actuator piston of which can be acted upon in the disengagement direction of the parking lock with clutch pressure of a clutch that is closed in the transmission. In the insertion direction of the parking lock, the spring force of an insertion spring of the parking lock acts on the actuator piston. In addition, the actuator piston can be locked mechanically by means of an electromagnet both in a piston position assigned to the engaged state of the parking lock and in a piston position assigned to the disengaged state of the parking lock. Such a mechanical securing of the actuator piston is also referred to as “bi-stable piston locking”.

For and when disengaging the parking lock, the mechanical piston locking is deactivated - i.e. released - and clutch pressure is applied to the actuator piston so that the clutch pressure brings the parking lock into the disengaged state against the spring force of the insert spring. When the parking lock is disengaged, the mechanical piston locking is activated again, thus preventing the actuator piston from moving unintentionally. In addition, when the parking lock is disengaged, the actuation of the clutch pressure on the actuator piston remains active, provided the transmission is operated in a gear in which the clutch that provides the pressure for the parking lock actuator is closed. In all other gears, the activated mechanical piston lock prevents the parking lock system from accidentally engaging the parking lock.

Proceeding from this, the invention is based on the object of creating a method for controlling a hydraulically actuated parking lock actuator that acts on a parking lock for engaging and disengaging the same, the actuator piston of which can be acted upon in the disengagement direction of the parking lock with clutch pressure of a transmission-side clutch and a two-way has stable piston locking, which prevents unintentional engagement of the parking lock in the event of a serious fault in the parking lock system with a previously designed parking lock.

This object is achieved by a method with the features of claim 1. Advantageous refinements and developments of the invention emerge from the subclaims and the following description.

Accordingly, the invention is based on a method for controlling a hydraulically actuable actuator of a parking lock system with a parking lock provided for locking a motor vehicle in a transmission of the motor vehicle, the actuator for actuating the parking lock having an actuator piston which is axially displaceable in a housing and which is used in the A clutch pressure of a clutch closed in the transmission can be applied to the parking lock in a leading manner, the actuator piston being mechanically lockable both in a piston position assigned to the engaged state of the parking lock and in a piston position assigned to the disengaged state of the parking lock by means of a locking device.

The lock can preferably be actuated by means of an electromagnet, in particular in such a way that the actuator piston is blocked against axial displacement when this electromagnet is de-energized. As an alternative to this, an electric motor, for example, can be provided for actuating the lock.

• • ein Fahrer des Kraftfahrzeugs wird gewarnt;
• • die Arretierung des Aktuatorkolbens wird gelöst;
• • befindet sich das Getriebe zum Zeitpunkt der Erkennung des Defekts in einem Gang, in welchem die den Aktuator mit Kupplungsdruck versorgende Kupplung zugeschaltet ist, also in Schlupf betrieben oder geschlossen ist, so wird der Kupplungsdruck dieser Kupplung steuerungsseitig auf einen vordefinierten Maximalwert gebracht, befindet sich das Getriebe zum Zeitpunkt der Erkennung des Defekts hingegen in einem Gang, in welchem die den Aktuator mit Kupplungsdruck versorgende Kupplung abgeschaltet ist, so wird der Kraftschluss im Getriebe unterbrochen und anschließend - vorzugsweise unmittelbar anschließend - der Kupplungsdruck dieser Kupplung steuerungsseitig auf einen vordefinierten Maximalwert gebracht;
• • nach der Anhebung des Kupplungsdrucks auf den Maximalwert wird im Getriebe solange, wie der Defekt erkannt ist, nur ein solcher Gang zugelassen, in dem die den Aktuator mit Kupplungsdruck versorgende Kupplung zugeschaltet bleibt.

According to the invention, if a defect is detected in the parking lock system when the parking lock is disengaged, which could lead to an unintentional engagement of the parking lock, the following method steps are carried out:

• • a driver of the motor vehicle is warned;
• • the locking of the actuator piston is released;
• • is the transmission in a gear at the time the defect is detected, in which the clutch supplying the actuator with clutch pressure is switched on, i.e. operated in slip or closed, the clutch pressure of this clutch is brought to a predefined maximum value on the control side, whereas the transmission is in a gear at the time the defect is detected If the clutch supplying the actuator with clutch pressure is switched off, the frictional connection in the transmission is interrupted and then - preferably immediately afterwards - the clutch pressure of this clutch is brought to a predefined maximum value on the control side;
• • After the clutch pressure has been increased to the maximum value, as long as the defect is recognized, only one gear is permitted in the transmission in which the clutch supplying the actuator with clutch pressure remains engaged.

It is preferably provided as an additional process step that if a shift command for engaging the parking lock is detected in the meantime via the selection device, the clutch pressure of the clutch supplying the actuator with hydraulic fluid is reduced to a predefined minimum value or switched off so that the parking lock is activated by means of the spring force of an insert spring of the parking lock system is engaged mechanically and the driver's request to engage the parking lock is followed. Subsequent to the lowering or disconnection of the clutch pressure of the clutch supplying the actuator with hydraulic fluid, the locking device previously controlled in a suitable manner for releasing is now controlled in a suitable manner for locking, so that subsequently the actuator piston is mechanically locked again and thus against a parking lock disengaging leading axial movement is secured.

In addition, it can be provided that all other clutches of the transmission are opened simultaneously with or immediately after the lowering or disconnection of the clutch pressure of the clutch supplying the actuator with hydraulic fluid, so that a frictional connection in the transmission is reliably prevented.

The method according to the invention is preferably implemented in the same electronic control unit which also controls the clutches of the transmission for gear formation.

The selection of the permitted gear when a defect is detected in the transmission, in which the clutch supplying the actuator piston with clutch pressure is operated in slip or is engaged, is preferably made as a function of the current driving speed of the motor vehicle. As an alternative to this, it can also be provided, for example, that only a single predefined gear is permitted in the transmission after a defect has been detected, in which the clutch supplying the actuator piston with clutch pressure is operated in slip or is closed.

The method according to the invention thus provides a type of replacement driving program for the restricted operation of the transmission and motor vehicle if the transmission-side parking lock should be able to engage inadvertently due to a fault in the parking lock system and its activation. In this case, the method according to the invention secures the transmission reliably and in a particularly advantageous manner, even in the event of individual double faults, against unwanted fault-related engagement of the parking lock without additional component-related expense. The availability of the motor vehicle for an even if restricted driving operation is accordingly increased significantly.

For the detection of a defect in the parking lock system, which could lead to an unwanted engagement of the parking lock, numerous different signals can be evaluated within the scope of the method according to the invention.

In a preferred embodiment of the invention, it is provided that signals from a device provided in the parking lock system for recognizing the current switching position of the locking device of the actuator piston are evaluated in order to detect the defect. A displacement sensor, an electrical switch or also an optical sensor, each arranged on the locking device acting on the actuator piston, are suitable for such a detection. Alternatively, the current switch position of the locking of the actuator piston can also be determined using a measuring method in which the current switch position of this lock is deduced from measured current values of the electrical control of an electromagnet provided for controlling the locking of the actuator piston.

Another embodiment of the invention provides that signals from a device provided in the parking lock system for recognizing the current piston position of the actuator piston are evaluated in order to identify the defect. A displacement sensor, for example, is suitable for such a detection. Alternatively, the current piston position of the actuator piston can also be determined with the aid of electrical switches. The current piston position can be sensed on the actuator piston itself, on a piston rod of the actuator piston or also on an actuator mechanically connected to the actuator piston.

In yet another embodiment of the invention, it is provided that signals from a device provided in the parking lock system for detecting the current shift position of a locking element, in particular a pawl of the parking lock, are evaluated in order to detect the defect. Again, both a sensor and an electrical switch are suitable for such a detection.

In further refinements of the invention it is proposed to evaluate signals from a selector device operable by the driver of the motor vehicle for specifying shift positions in the transmission, signals from an electrical control of the locking device and signals from an activation of the clutch supplying the actuator piston with clutch pressure to detect the defect. In addition, it is advantageous to monitor signals from an electronic control device provided for operating the transmission with regard to error value and / or failure and / or plausibility in order to detect the defect.

• • Auf einen mechanischen Defekt im Parksperrensystem kann beispielsweise dann geschlossen werden, wenn die sensierte Kolbenstellung des Aktuatorkolbens oder auch die sensierte Schaltposition des Parksperren-Sperrelementes nicht zu den steuerungstechnischen Vorgaben betreffend Schaltposition und Gang im Getriebe passt.
• • Auf das Vorliegen von potentiell falschen und damit für die Ansteuerung der Parksperre ungültigen Signalen der Vorrichtung, mittels der die tatsächliche Kolbenstellung des Aktuatorkolbens und/oder die tatsächliche Schaltposition des Parksperren-Sperrelementes ermittelt werden soll, kann beispielsweise dann geschlossen werden, wenn diese Vorrichtung unplausible Signale liefert. Ursache hierfür kann ein elektrischer Defekt oder auch eine unzulässige Toleranzabweichung innerhalb dieser Vorrichtung sein.
• • Auf einen Ausfall der Signale der für die Bestimmung der tatsächlichen Kolbenstellung des Aktuatorkolbens und/oder der tatsächlichen Schaltposition des Parksperren-Sperrelementes vorgesehenen Vorrichtung kann beispielsweise dann geschlossen werden, wenn diese Vorrichtung ein ungültiges oder gar kein Signal liefert. Ursache hierfür kann ein elektrischer Defekt innerhalb dieser Vorrichtung sein, aber auch eine fehlerhafte Justierung.
• • Auf eine falsche Ansteuerung der elektromagnetischen Arretierung des Aktuatorkolbens kann beispielsweise dann geschlossen werden, wenn an dem Steuergerät, welches den Elektromagneten der Arretierung ansteuert, ein elektrischer Kurzschluss erkannt wird.
• • Auf ein durch eine Außenstörung hervorgerufenes ungewolltes Lösen der Arretierung des Aktuatorkolbens kann beispielsweise dann geschlossen werden, wenn die sensierte Schaltstellung der Arretierung des Aktuatorkolbens und/oder die auf die Arretierung aktuelle wirkende Ansteuerlogik nicht zu der sensierten Kolbenstellung des Aktuatorkolbens und/oder nicht zu der sensierten Schaltposition des Sperrelementes der Parksperre passt.
• • Auf eine fehlerhafte Toleranzlage an oder in der zur Ermittlung der aktuellen Schaltstellung der Arretierung des Aktuatorkolbens vorgesehenen Vorrichtung kann beispielsweise dann geschlossen werden, wenn die sensierte Schaltstellung der Arretierung nicht zu der sensierten Kolbenstellung des Aktuatorkolbens und/oder nicht zu der sensierten Schaltposition des Sperrelementes der Parksperre passt.
• • Auf einen Ausfall der Signale der für die Bestimmung der Schaltstellung der Arretierung des Aktuatorkolbens vorgesehenen Vorrichtung kann beispielsweise dann geschlossen werden, wenn diese Vorrichtung ein ungültiges oder gar kein Signal liefert. Als Ursache hierfür kommt insbesondere ein elektrischer Defekt innerhalb dieser Vorrichtung in Betracht, beispielsweise aber auch eine fehlerhafte Justierung.
• • Auf einen Logikfehler in der Ansteuerung des Parksperren-Aktuators kann beispielsweise dann geschlossen werden, wenn mittels der zur Bestimmung der Kolbenstellung des Aktuatorkolbens und/oder der Schaltposition des Sperrelementes der Parksperre vorgesehenen Vorrichtung ein Lösen der Arretierung des Aktuatorkolbens erkannt wird, obwohl sich die fahrerseitig bedienbare Wähleinrichtung nicht in Schaltposition „Parken“ bewegt hat.
• • Auf einen Logikfehler in der Ansteuerung des Parksperren-Aktuators kann beispielsweise auch dann geschlossen werden, wenn das elektronische Getriebesteuergerät mittels Eigenüberwachung seiner hardwareseitigen Komponenten einen Redundanzverlust und/oder eine fehlerhafte Bestromung der zur Ansteuerung des Parksperren-Aktuators vorgesehenen Komponenten erkennt.

The defects in the parking lock system, which could lead to unwanted engagement of the previously designed parking lock, are of a diverse nature and can in particular be mechanical, hydraulic, electrical and / or electronic:

• • A mechanical defect in the parking lock system can be concluded, for example, if the sensed piston position of the actuator piston or the sensed shift position of the parking lock locking element does not match the control specifications regarding shift position and gear in the transmission.
• • The presence of potentially false and thus invalid signals from the device for activating the parking lock, by means of which the actual piston position of the actuator piston and / or the actual switching position of the parking lock locking element is to be determined, can be concluded, for example, if this device is implausible Signals. The cause for this can be an electrical defect or an impermissible tolerance deviation within this device.
• • A failure of the signals of the device provided for determining the actual piston position of the actuator piston and / or the actual switching position of the parking lock locking element can be concluded, for example, if this device delivers an invalid signal or no signal at all. The cause for this can be an electrical defect within this device, but also an incorrect adjustment.
• • Incorrect activation of the electromagnetic lock of the actuator piston can be concluded, for example, when an electrical short circuit is detected on the control device that controls the electromagnet of the lock.
• • An unintentional release of the locking of the actuator piston caused by an external disturbance can be concluded, for example, if the sensed switching position of the locking of the actuator piston and / or the control logic currently acting on the locking does not correspond to the sensed piston position of the actuator piston and / or not to the sensed switching position of the locking element of the parking lock fits.
• • A faulty tolerance position on or in the device provided for determining the current switch position of the lock of the actuator piston can be concluded, for example, if the sensed switch position of the lock does not correspond to the sensed piston position of the actuator piston and / or not to the sensed switch position of the locking element Parking lock fits.
• • A failure of the signals of the device provided for determining the switching position of the locking of the actuator piston can be concluded, for example, if this device delivers an invalid signal or no signal at all. A possible cause for this is in particular an electrical defect within this device, but also, for example, an incorrect adjustment.
• • A logic error in the activation of the parking lock actuator can be deduced, for example, if the device provided for determining the piston position of the actuator piston and / or the switching position of the locking element of the parking lock detects a release of the locking of the actuator piston, even though it is on the driver's side has not moved the operable selection device to the "Parking" switch position.
• • A logic error in the control of the parking lock actuator can also be deduced, for example, if the electronic transmission control unit detects a loss of redundancy and / or an incorrect current supply to the components provided for controlling the parking lock actuator by means of self-monitoring of its hardware components.

The detected defect is preferably also documented in a fault memory of the electronic control device in which the method according to the invention is implemented.

• 1 eine schematische Darstellung eines Kraftfahrzeugs umfassend ein Getriebe mit einer Parksperre;
• 2 eine schematische Darstellung eines mit Kupplungsdruck beaufschlagbaren Parksperren-Aktuators für die Parksperre in dem Getriebe gemäß 1; und
• 3 ein vereinfachtes Funktionsablaufdiagramm eines erfindungsgemäßen Verfahrens zur Ansteuerung des Parksperren-Aktuators gemäß 2.

Exemplary embodiments of the invention are explained in more detail with reference to the drawings, without being restricted thereto. It shows:

• 1 a schematic representation of a motor vehicle comprising a transmission with a parking lock;
• 2 a schematic representation of a parking lock actuator that can be acted upon by clutch pressure for the parking lock in the transmission according to FIG 1 ; and
• 3 a simplified functional flow diagram of a method according to the invention for controlling the parking lock actuator according to FIG 2 .

1 shows a schematic representation of a motor vehicle 1 with a gear 4th , which at least one gear-forming clutch 5 has and a starting element 3 from a drive motor 2 is drivable. In this way, the driving power of the drive motor is 2 in preferably several different gears or gear steps on one output shaft 7th of the transmission 4th transferable. The output shaft 7th is about more in 1 Motor vehicle components (not shown) with a drive axle of the motor vehicle 1 effectively connected. In addition, the transmission 4th a parking lock 6th on, by means of which the output shaft 7th and thus the motor vehicle can also be fixed. To control the transmission 4th is an electronic control unit 8th provided, which for this purpose, among other things, signals a dialing device 9 processed by means of a driver of the motor vehicle 1 can specify individual shift positions for the transmission, in particular the shift positions "Park", "Forward" and "Reverse".

The parking lock can be activated 6th by means of one of the cited at the beginning DE 10 2017 211 025 A1 known actuator, the piston with a locking element of the parking lock 6th is operatively connected and to deploy the parking lock 6th Clutch pressure of a closed - that is, gear forming - clutch of the transmission is applied, which is shown below with reference to FIG 2 is explained in more detail.

This actuator is in 2 with reference numerals 10 provided and has an actuator piston 11 between an insertion position E. , at which the parking lock 6th the output shaft 7th of the transmission 4th blocked and the in 2 is shown in dashed lines, and a deployment position A. , at the parking lock 6th the output shaft 7th of the transmission 4th not blocked, axially movable. The actuator piston is for this purpose 11 in a cylinder interior 13th of a cylinder 12th of the actuator 10 axially displaceable, this cylinder interior 13th Hydraulic fluid can be supplied to the actuator piston 11 in the display A. to move. A piston rod acts here 17th of the actuator piston 11 Mechanically to the parking lock via a suitable operative connection 6th .

In addition, the actuator 10 a locking device 20th for mechanical locking of the actuator piston 11 and its piston rod 17th on. This locking device 20th includes a pen 21 and one to operate the pen 21 provided electromagnet 22nd , with the pen 21 preferably in the de-energized state of the electromagnet 22nd the actuator piston 11 and the piston rod 17th optionally in the insertion position E. or the display A. locked, so secures against unwanted axial displacement. In 2 is the pen 21 shown in the extended position, in which he is against one on the piston rod 17th attached tab 18th bumps. The pencil 21 prevents actuator piston from moving 11 and piston rod 17th in the loading position E. move. Is the electromagnet 22nd in the extended position of the pin 21 de-energized, the pen can 21 be held in its extended position, for example by means of a spring force, this spring force then being controlled by the actuating force of the electromagnet 22nd must be overcome to the pen 21 to move to its retracted position.

The actuator can be controlled hydraulically 10 via an electrohydraulic control unit, not shown in detail here, which is also used to control gear-forming clutches of the transmission 4th is provided and for this purpose by a pump 31 of the transmission 4th is supplied with hydraulic fluid. The electrohydraulic control device includes at least one pressure control valve 33 , which on the input side via a first hydraulic line 32 to the pressure outlet of the pump 31 and on the output side via a second hydraulic line 34 to a clutch 5 of the transmission 4th is hydraulically coupled. The pressure control valve is used accordingly 33 for controlling or regulating the fluid supply to the clutch 5 , the clutch 5 is actuated or closed when hydraulic fluid is supplied. At a junction 35 branches from the second hydraulic line 34 a third hydraulic line 36 from which in turn the cylinder interior 13th of the actuator 10 supplied with hydraulic fluid. This allows by means of the pressure control valve 33 controlled or regulated whether the parking lock 6th is operated.

This influences the valve position of the pressure regulating valve 33 both the switching status of the clutch 5 as well as the switching status of the parking lock 6th . To this end, the pressure control valve 33 at least two electromagnetically adjustable valve positions. With an in 2 First valve position, not shown, there is a fluidic connection between the hydraulic line 34 and one from the pressure control valve 33 upstream Hydraulic line 32 which in turn are in fluid communication with the pump 31 stands that the hydraulic fluid from an in 2 not shown in detail fluid reservoir of the transmission 4th promotes. As a result, this can be done by the pump in this valve position 31 pumped hydraulic fluid through the hydraulic line 32 and the pressure control valve 33 in to the clutch 5 leading hydraulic line 34 and thus also to the actuator 10 leading hydraulic line 36 stream. With an in 2 illustrated second valve position of the pressure control valve 33 however, there is no fluidic connection between the hydraulic line 34 and hydraulic line 32 .

The actuator piston 11 of the actuator 10 separates the cylinder interior 13th into a first cavity 14th , the one with the third hydraulic line 36 is fluidly connected and a second cavity 15th . In this second cavity 15th is an insert spring 16 arranged which the actuator piston 11 opposite the cylinder 12th preloaded to a predefined amount. The actuator piston 11 is with the piston rod 17th non-rotatably connected, which in turn have an in 2 Operational connection not shown in detail with the parking lock 6th is effectively connected. The operative connection is designed in such a way that in the event that the actuator piston 11 and piston rod 17th in insertion position E. are located, the parking lock locks and in the event that the actuator piston 11 and piston rod 17th in display A. located, the parking lock 6th does not lock.

When hydraulic fluid is fed into the first cavity 14th the actuator piston moves 11 in the display A. , with the insert spring 16 is further stretched. The inlay spring 16 exercises on the actuator piston 11 thus a force in the direction of the insertion position E. the end. The actuator piston 11 moves towards the loading position E. if that's in the first cavity 14th the hydraulic fluid located is no longer sufficiently pressurized.

The in 3 The first exemplary embodiment illustrated is a simplified functional flow diagram of a method according to the invention for controlling the one cited from FIG DE 10 2017 211 025 A1 known parking lock actuator.

• • eine Eigendiagnose des elektronischen Steuergerätes, mittels der die für die Druckversorgung des Parksperren-Aktuators vorgesehene Getriebe-Kupplung angesteuert wird und mittels der die Arretierung des Aktuatorkolbens angesteuert wird;
• • eine Vorrichtung zur Erkennung der tatsächlich vom Fahrer des Kraftfahrzeugs via Wähleinrichtung vorgegebenen Schaltposition für das Getriebe;
• • eine Vorrichtung zur Sensierung der tatsächlichen Schaltstellung der auf den Aktuatorkolben wirkenden Arretierung; sowie
• • eine Vorrichtung zur Sensierung der tatsächlichen Kolbenstellung des (zum Auslegen der Parksperre mit Kupplungsdruck einer geschlossenen gangbildenden Kupplung des Getriebes beaufschlagbaren) Aktuatorkolbens, alternativ hierzu oder auch zusätzlich eine Vorrichtung zur Sensierung der tatsächlichen Schaltposition des (zum Blockieren der Getriebe-Abtriebswelle vorgesehenen) Sperrelementes der Parksperre.

With reference number S1 The start of this diagnostic function is designated, which is expediently carried out in the control software of the electronic control unit 8th of the transmission 4th is integrated. After the diagnostic function has started, a first query block A1 checked whether there is an error in the parking lock system of the transmission in the "parking lock disengaged" state, which could lead to an unintentional engagement of the parking lock. In order to be able to recognize such errors, the transmission preferably has

• A self-diagnosis of the electronic control unit, by means of which the transmission clutch provided for the pressure supply of the parking lock actuator is activated and by means of which the locking of the actuator piston is activated;
• A device for recognizing the shift position for the transmission actually specified by the driver of the motor vehicle via a selector device;
• • a device for sensing the actual switch position of the lock acting on the actuator piston; as
• • a device for sensing the actual piston position of the actuator piston (which can be acted upon by clutch pressure of a closed gear-forming clutch of the transmission to disengage the parking lock), alternatively or additionally a device for sensing the actual shift position of the locking element of the (provided for blocking the transmission output shaft) Parking lock.

• • Auf einen Logikfehler in der Ansteuerung des Parksperren-Aktuators kann beispielsweise geschlossen werden, wenn das elektronische Getriebesteuergerät mittels Eigenüberwachung seiner hardwareseitigen Komponenten einen Redundanzverlust und/oder eine fehlerhafte Bestromung der zur Ansteuerung des Parksperren-Aktuators vorgesehenen Komponenten erkennt.
• • Auf einen Logikfehler in der Ansteuerung des Parksperren-Aktuators kann beispielsweise auch dann geschlossen werden, wenn mittels der zur Bestimmung der Kolbenstellung des Aktuatorkolbens und/oder der Schaltposition des Sperrelementes der Parksperre vorgesehenen Vorrichtung ein Lösen der Arretierung des Aktuatorkolbens erkannt wird, obwohl sich die fahrerseitig bedienbare Wähleinrichtung nicht in Schaltpositionen „Parken“ bewegt hat.
• • Auf eine falsche Ansteuerung der elektromagnetisch betätigbaren Arretierung des Aktuatorkolbens kann beispielsweise dann geschlossen werden, wenn an dem elektronischen Steuergerät, welches den Elektromagneten der Arretierung ansteuert, ein elektrischer Kurzschluss erkannt wird.
• • Auf ein durch eine Außenstörung hervorgerufenes ungewolltes Lösen der Arretierung des Aktuatorkolbens kann beispielsweise dann geschlossen werden, wenn die sensierte Schaltstellung der (auf den Aktuatorkolben wirkenden) Arretierung und/oder die auf die Arretierung aktuelle wirkende Ansteuerlogik nicht zu der sensierten Kolbenstellung des Aktuatorkolbens und/oder nicht zu der sensierten Schaltposition des Sperrelementes der Parksperre passt.
• • Auf eine fehlerhafte Toleranzlage an oder in der Vorrichtung, mittels der die aktuellen Schaltstellung der (auf den Aktuatorkolben wirkenden) Arretierung ermittelt werden soll, kann beispielsweise dann geschlossen werden, wenn die sensierte Schaltstellung der Arretierung nicht zu der sensierten Kolbenstellung des Aktuatorkolbens und/oder nicht zu der sensierten Schaltposition des Sperrelementes der Parksperren passt.
• • Auf einen Ausfall der Signale der Vorrichtung, mittels der die aktuelle Schaltstellung der (auf den Aktuatorkolben wirkenden) Arretierung ermittelt werden soll, kann beispielsweise dann geschlossen werden, wenn diese Vorrichtung - beispielsweise infolge eines elektrischen Defekts innerhalb dieser Vorrichtung oder beispielsweise infolge einer fehlerhaften Justierung - ein ungültiges oder gar kein Signal liefert.
• • Auf einen mechanischen Defekt im Parksperrensystem kann beispielsweise dann geschlossen werden, wenn die sensierte Kolbenstellung des Aktuatorkolbens oder auch die sensierte Schaltposition des Parksperren-Sperrelementes nicht zu den steuerungstechnischen Vorgaben betreffend Schaltposition und Gang im Getriebe passt.
• • Auf das Vorliegen von potentiell falschen und damit für die Ansteuerung der Parksperre ungültigen Signalen der Vorrichtung, mittels der die tatsächliche Kolbenstellung des Aktuatorkolbens und/oder die tatsächliche Schaltposition des Parksperren-Sperrelementes ermittelt werden soll, kann beispielsweise dann geschlossen werden, wenn diese Vorrichtung - beispielsweise infolge eines elektrischen Defekts oder einer unzulässigen Toleranzabweichung innerhalb dieser Vorrichtung - unplausible Signale liefert.
• • Auf einen Ausfall der Signale der für die Bestimmung der tatsächlichen Kolbenstellung des Aktuatorkolbens und/oder der tatsächlichen Schaltposition des Parksperren-Sperrelementes vorgesehenen Vorrichtung kann beispielsweise dann geschlossen werden, wenn diese Vorrichtung - beispielsweise infolge eines elektrischen Defekts innerhalb dieser Vorrichtung oder infolge einer fehlerhaften Justierung - ein ungültiges oder gar kein Signal liefert.

In the following, examples of possible defects in the parking lock system are listed that could lead to an unintentional engagement of the parking lock.

• • A logic error in the control of the parking lock actuator can be inferred, for example, if the electronic transmission control unit detects a redundancy loss and / or incorrect current supply to the components provided for controlling the parking lock actuator by means of self-monitoring of its hardware components.
• • A logic error in the control of the parking lock actuator can also be deduced, for example, if the device provided for determining the piston position of the actuator piston and / or the switching position of the locking element of the parking lock detects a release of the locking of the actuator piston, although the The driver-operated selector device has not moved to the "Parking" switch position.
• • Incorrect control of the electromagnetically actuated lock of the actuator piston can be concluded, for example, when an electrical short circuit is detected on the electronic control device that controls the electromagnet of the lock.
• • Unintentional loosening of the lock of the actuator piston caused by an external malfunction can be concluded, for example, if the sensed switching position of the (acting on the actuator piston) The locking and / or the control logic currently acting on the locking does not match the sensed piston position of the actuator piston and / or does not match the sensed switching position of the locking element of the parking lock.
• A faulty tolerance position on or in the device by means of which the current switch position of the lock (acting on the actuator piston) is to be determined can be concluded, for example, if the sensed switch position of the lock does not correspond to the sensed piston position of the actuator piston and / or does not match the sensed switching position of the locking element of the parking locks.
• A failure of the signals of the device by means of which the current switch position of the lock (acting on the actuator piston) is to be determined can be concluded, for example, if this device - for example as a result of an electrical defect within this device or, for example, as a result of an incorrect adjustment - supplies an invalid signal or no signal at all.
• • A mechanical defect in the parking lock system can be concluded, for example, if the sensed piston position of the actuator piston or the sensed shift position of the parking lock locking element does not match the control specifications regarding shift position and gear in the transmission.
• • The presence of potentially incorrect and thus invalid signals from the device for activating the parking lock, by means of which the actual piston position of the actuator piston and / or the actual switching position of the parking lock locking element is to be determined, can be concluded, for example, if this device - for example as a result of an electrical defect or an impermissible tolerance deviation within this device - supplies implausible signals.
• • A failure of the signals of the device provided for determining the actual piston position of the actuator piston and / or the actual switching position of the parking lock locking element can be concluded, for example, if this device - for example as a result of an electrical defect within this device or as a result of incorrect adjustment - supplies an invalid signal or no signal at all.

Returns the query in the first query block A1 a positive result, i.e. if there is an error in the parking lock system which could lead to an unintentional engagement of the parking lock, the diagnostic function is started with a first function block F1 continued, otherwise there is a return immediately before the query block A1 .

In this first function block F1 a driver warning is initiated and, at the same time or immediately afterwards, the mechanical locking of the actuator piston and piston rod that is in effect at this point in time is released. If the locking device is designed, for example, as an electromagnetically actuated pin that can positively block axial movement of the actuator piston and piston rod when the corresponding electromagnet is de-energized, the electromagnet acting on the pin is in the function block F1 energized, which leads to the release of the locking of the actuator piston. If, however, the locking acting on the actuator piston and the piston rod can be actuated by an electric motor, for example, then in the function block F1 the corresponding electric motor is controlled in such a way that the lock is released.

The one in the function block F1 The driver warning that is issued can, for example, take place optically and / or acoustically and / or haptically. A visual driver warning preferably maintains the diagnostic function until the first query block A1 previously recognized defect in the parking lock system is no longer present.

Preferably in the function block F1 also the one in the first query block A1 detected defect in a fault memory of the electronic control unit in which the method according to the invention is implemented, documented.

After processing the first function block F1 the diagnostic function is continued with a second query block A2 , in which it is checked whether the driver of the motor vehicle changes his shift position previously specified by means of the selection device for the transmission, that is, actuates the selection device. Used in the query block A2 recognized that the driver is the transmission shift position P. - ie "Parking" - is desired, the diagnostic function is provided with a second function block F2 continued.

In this second function block F2 the clutch pressure of the clutch that also supplies the parking lock actuator with hydraulic fluid is reduced to a predefined minimum value by the electrohydraulic transmission control or is switched off entirely. This at least reduced clutch pressure has the effect that the insert spring moves the actuator piston in the direction leading to the engagement of the parking lock. Then in the second function block F2 following the lowering or disconnection of the clutch pressure of the clutch supplying the parking lock actuator with hydraulic fluid, the actuator piston is locked against one another by means of the locking mechanism Axial movement leading to disengaging the parking lock is secured.

In one to the second function block F2 subsequent third function block F3 all other clutches of the transmission are opened so that a frictional connection in the transmission is safely prevented. After processing the function block F3 there is a return immediately before the query block A1 . Accordingly, the driver's request to engage the parking lock is always followed.

Used in the query block A2 however, recognized that the driver-operated selector device remains unchanged in the gear shift position N , D. or R. - ie "Neutral" or "Forward travel" or "Reverse travel" - is located or in one of these gear shift positions N , D. or R. ("Neutral", "Forward travel" or "Reverse travel") is brought, the diagnostic function is based on the query block A2 in a fourth function block F4 continued.

In this fourth function block F4 All clutches of the transmission except for the clutch whose clutch pressure also acts on the actuator piston of the parking lock actuator are opened immediately so that the transmission is safely in a non-positive state, but the parking lock actuator is still supplied with hydraulic fluid. At the same time as the power connection interruption or immediately afterwards, the clutch pressure of that clutch that also supplies the parking lock actuator with hydraulic fluid is raised to a predefined maximum value by the electrohydraulic transmission control. This now increased clutch pressure also acts on the actuator piston with the maximum possible force in the direction of force acting to disengage the parking lock. The diagnostic function is then continued with a third query block A3 .

In this third query block A3 the exact shift position of the driver-operated selection device for the transmission gear setting is checked. Used in the query block A3 recognized that the driver is the transmission shift position N - ie "Neutral" - the diagnostic function is provided with a fifth function block F5 continued, in which the transmission is kept in a non-positive state as long as the electronic transmission control unit is not switched off and as long as that in the first query step A1 previously recognized defect in the parking lock system is still present. This is done after the function block has been processed F5 a return immediately before the query block A1 .

Used in the query block A3 however, recognized that the driver is the transmission shift position R. - that is, "backward travel" - is desired, the diagnostic function is provided with a sixth function block F6 continued, in which the electrohydraulic transmission control engages reverse gear in the transmission. The prerequisite here is that the clutch that also supplies the parking lock actuator with hydraulic fluid is involved in the formation of the reverse gear, i.e. must be closed in the reverse gear and, in the present case, is now activated with the predefined maximum pressure. In contrast to this, if the clutch that also supplies the parking lock actuator with hydraulic fluid is not involved in the gear formation of the reverse gear due to the transmission concept, i.e. to be kept open in reverse gear, then in the sixth function block F6 the transmission brought into a non-positive state and kept in this non-positive state as long as the electronic transmission control unit is not switched off and as long as the in the first query block A1 previously recognized defect in the parking lock system is still present. This takes place accordingly after the function block has been processed F6 a return immediately before the query block A1 .

Used in the query block A3 however, realized that the driver is the transmission shift position D. - ie "forward travel" - is desired, the diagnostic function is provided with a seventh function block F7 continued, in which the forward driving range of the motor vehicle is limited to those forward gears in which the clutch that also supplies the parking lock actuator with hydraulic fluid is closed - that is, involved in gear formation. In the eighth function block below F8 Such a forward gear is then engaged by the electrohydraulic transmission control, whereby the clutch, which was previously activated with maximum pressure and which also keeps the parking lock actuator under the maximum possible activation pressure with hydraulic fluid, remains activated at this maximum pressure level. The forward gear is preferably selected as a function of the current vehicle speed in order to utilize the operating range of the motor vehicle that is still permitted (despite a defect in the parking lock system) as far as possible.

The diagnosis function keeps the in the function blocks F7 and F8 The restrictions met as long as the electronic gearbox control unit is not switched off and as long as the one in the first query block A1 previously recognized defect in the parking lock system is still present. This is done after the function block has been processed F8 a return immediately before the query block A1 .

List of reference symbols

1

Motor vehicle

2

Drive motor of the motor vehicle

3

Starting element of the motor vehicle

4th

Transmission of the motor vehicle

5

Clutch of the transmission

6th

Parking lock of the transmission

7th

Output shaft of the gearbox

8th

electronic control unit of the transmission

9

Dialing device

10

Parking lock actuator

11

Actuator piston of the actuator

12th

Cylinder of the actuator

13th

Cylinder interior

14th

first cavity of the cylinder

15th

second cavity of the cylinder

16

Insertion spring of the parking lock

17th

Actuator piston rod

18th

Protrusion of the piston rod

20th

Locking device

21st

Locking device pin

22nd

Locking device electromagnet

31

pump

32

first hydraulic line

33

Pressure control valve

34

second hydraulic line

35

Junction

36

third hydraulic line

A.

Design of the actuator piston and piston rod

E.

Insertion of the actuator piston and piston rod

P.

"Parking" switch position on the dialing device

R.

"Reverse" switching position on the selector

N

Switching position "Neutral" on the selection device

D.

Switching position "forward travel" on the selection device

S1

Starting point of the function

A1

first query block

A2

second query block

A3

third query block

F1

first function block

F2

second function block

F3

third function block

F4

fourth function block

F5

fifth function block

F6

sixth function block

F7

seventh function block

F8

eighth function block

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was 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.

Patent literature cited

• DE 102017211025 A1 [0004, 0025, 0032]

Claims (20)

Method for controlling a hydraulically operated actuator (10) of a parking lock system with a parking lock (6) provided for locking a motor vehicle (1) in a transmission (4) of the motor vehicle (1), the actuator (10) for operating the parking lock (6 ) has an actuator piston (11) which is arranged axially displaceably in a housing and can be acted upon in a manner leading to disengagement of the parking lock (6) with a clutch pressure of a clutch (5) closed in the transmission (4), the actuator piston (11) both can be mechanically locked in a piston position (E) assigned to the engaged state of the parking lock (6) and also in a piston position (A) assigned to the disengaged state of the parking lock by means of a locking device (20), characterized in that when the parking lock ( 6) a defect is recognized in the parking lock system, which could lead to an unintentional engagement of the parking lock (6), the following Ve Method steps are carried out: a driver of the motor vehicle (1) is warned; • the locking of the actuator piston (11) is released; • If the transmission (4) is in a gear at the time of detection of the defect in which the clutch (5) supplying the actuator (10) with clutch pressure is in slip or closed, the clutch pressure of this clutch (5) is increased to one Brought predefined maximum value, the transmission (4) is at the time of detection of the defect, however, in a gear in which the clutch (5) supplying the actuator (10) with clutch pressure is switched off, the frictional connection in the transmission (4) is interrupted and then the clutch pressure of this clutch (5) is brought to a predefined maximum value; • After the clutch pressure has been increased to the maximum value, only one gear is permitted in the gearbox (4) as long as the defect is recognized in which the clutch (5) supplying the actuator (10) with clutch pressure remains engaged. Procedure according to Claim 1 , characterized in that it is provided as an additional process step that when a driver-side shift command to engage the parking lock (6) is recognized after the defect is recognized, the clutch pressure of the clutch (5) supplying the actuator (10) with hydraulic fluid is set to a predefined Minimum value is lowered or switched off, so that the parking lock (6) is engaged by means of the spring force of an insertion spring (16) of the parking lock system, the actuator piston (11) being mechanically locked again after this clutch pressure is lowered or switched off. Procedure according to Claim 2 , characterized in that it is provided as an additional process step that all other clutches of the transmission (4) are opened at the same time or immediately after the lowering or switching off of the clutch pressure of the clutch (5) supplying the actuator (10) with hydraulic fluid. Procedure according to Claim 1 , 2 or 3 , characterized in that signals from a device provided in the parking lock system for recognizing the current switching position of the lock (20) of the actuator piston (11) are evaluated to detect the defect. Procedure according to Claim 4 , characterized in that a sensor is used to detect the current switch position of the lock (20) of the actuator piston (11). Procedure according to Claim 4 , characterized in that an electrical switch is used to detect the current switch position of the lock (20) of the actuator piston (11). Procedure according to Claim 4 , characterized in that a measuring method is used to detect the current switch position of the lock (20) of the actuator piston (11) by means of which, from measured current values, the electrical control of an electromagnet (22) provided for actuating the lock (20) of the actuator piston (11) ) the locking device (20) is closed to the current switching position of the locking of the actuator piston (11). Method according to one of the Claims 1 until 6th , characterized in that signals from a device provided in the parking lock system for recognizing the current piston position of the actuator piston (11) are evaluated to detect the defect. Procedure according to Claim 8 , characterized in that a displacement sensor is used to detect the current piston position of the actuator piston (11). Procedure according to Claim 8 , characterized in that electrical switches are used to detect the current piston position of the actuator piston (11). Method according to one of the Claims 1 until 10 , characterized in that signals from a device provided in the parking lock system for detecting the current shift position of a locking element of the parking lock (6) are evaluated to detect the defect. Procedure according to Claim 11 , characterized in that a sensor is used to detect the current switching position of the locking element. Procedure according to Claim 11 , characterized in that an electrical switch is used to detect the current switching position of the locking element. Method according to one of the Claims 1 until 13th , characterized in that, in order to detect the defect, signals from a selection device (9) which can be operated by the driver of the motor vehicle (1) for specifying shift positions in the transmission (4) are evaluated. Method according to one of the Claims 1 until 14th , characterized in that signals of an electrical control of the locking device (20) are evaluated to detect the defect. Method according to one of the Claims 1 until 15th , characterized in that signals of a control of the clutch (5) supplying the actuator piston (11) with clutch pressure are evaluated to detect the defect. Method according to one of the Claims 1 until 16 , characterized in that, in order to detect the defect, signals from an electronic control device (8) provided for operating the transmission (4) are monitored with regard to errors and / or failure and / or plausibility. Method according to one of the Claims 1 until 17th , characterized in that after the detection of a defect, the selection of the gear permitted in the transmission (4) in which the clutch (5) supplying the actuator piston (11) with clutch pressure is operated in slip or is closed, depending on a current driving speed of the Motor vehicle (1) takes place. Method according to one of the Claims 1 until 17th , characterized in that only one predefined gear is permitted in the transmission (4) after a defect has been detected, in which the clutch (5) supplying the actuator piston (11) with clutch pressure is operated in slip or is closed. Method according to one of the Claims 1 until 18th , characterized in that the detected defect is documented in a fault memory of the electronic control device (8) provided for operating the transmission (4).

Images