Method for actuating a fluid device in a motor vehicle

Abstract

The invention relates to a method for actuating a fluid device in a motor vehicle

Description

[0001] The invention relates to a method for actuating a fluid device in a motor vehicle according to the preamble of claim 1.

[0002] The ever-increasing complexity of vehicles demands flawless function and interaction of all components. The functionality of electrical components is particularly crucial for enabling purely electric driving and increasing efficiency. Failure or defect of certain electronic components can have serious consequences for the vehicle.

[0003] DE 10 2020 108 988 A1 discloses a method for operating a parking lock installed in a vehicle.

[0004] German patent application DE 10 2020 111 970 A1 describes a hydraulic device that supplies an actuating device with an actuating fluid pressure. A hybrid disconnect coupling is actuated depending on the actuating fluid pressure. A release valve is actuated to open the hybrid disconnect coupling, which causes a pressure drop in the actuating fluid pressure.

[0005] The as yet unpublished German patent application DE 10 2024 118 008 A1 discloses a method for verifying the plausibility of a path signal in a bistable parking lock, in particular for detecting the unintentional displacement of a sensor magnet in the actuator of the parking lock.

[0006] The as yet unpublished German patent application DE 10 2023 106 429 A1 discloses a method for detecting impermissibly high pressures in a hydraulic cylinder of a parking lock using a displacement sensor.

[0007] The as yet unpublished German patent application DE 10 2022 132 010 A1 discloses a method for detecting the end positions of a bistable parking lock without a position sensor.

[0008] The as yet unpublished German patent application DE 10 2023 108 130 A1 discloses a method for unlocking a parking lock comprising a parking lock actuator.

[0009] WO 2023 / 217 314 A1 discloses a magnet integrated in a sleeve for sensing the position of a hydraulic piston.

[0010] DE 10 2020 117 020 A1 discloses a parking lock actuation system with a positively locking locking element and a method for controlling the parking lock actuation system.

[0011] DE 10 2019 118 485 A1 discloses a method for detecting an emergency release of a parking lock.

[0012] DE 10 2019 124 561 A1 discloses an arrangement for deactivating a parking lock of a vehicle.

[0013] Many automated clutch systems have an actuator containing a movable piston, for example, a master cylinder with a master cylinder piston and a slave cylinder (CSC - Concentric Slave Cylinder) with a slave cylinder piston. The pistons interact with each other via a hydraulic fluid in a hydraulic line. Thus, a specific volume of fluid is displaced when the clutch is engaged. If the pressure is to be kept constant, the piston remains in one position. If too low or too high a pressure is detected, it is adjusted by moving the piston within the actuator. When no more pressure is required, the piston returns to its starting position, and the pressure drops to 0 bar. The clutch is actuated by a clutch actuator. The hydraulic fluid is also referred to as oil in the following text.

[0014] The fluid device, as used, for example, in Fig. As shown in Figure 1, a parking lock (PL) and a clutch are actuated by a pump actuator (SHA: Smart Hydraulic Actuator), which incorporates a fluid pump and is part of the fluid device. The pump actuator provides the necessary fluid flow to actuate both systems (park lock and clutch), and a switching valve distributes the fluid flow to either the parking lock or the clutch as needed. By default, the switching valve is in the "clutch" position. This means that as long as the switching valve is not energized, fluid pumped by the fluid pump is directed towards the clutch to close it, while the switching valve blocks the line to the parking lock.

[0015] The parking lock is actuated via the SHA pump actuator when the switching valve is energized. Actuation is achieved through position-dependent control. A position sensor in the parking lock determines the current position of the parking lock piston (PL: Park Lock) and transmits this information to the control unit (LCU) of the SHA pump actuator. As soon as the target position is reached, the SHA pump actuator stops pumping fluid into the parking lock and, if necessary, reverses its direction of rotation to cool other vehicle components. The fluid pump speed is temperature-dependent. At low temperatures, the speed is correspondingly lower than at high temperatures.

[0016] Before the transmission is delivered to the customer, the parking lock's position sensor is calibrated during end-of-line inspection. This means that the sensor's raw values ​​are mapped to the corresponding physical millimeter values. The magnet is mounted inside the parking lock's piston between a crimped sleeve and a rubber buffer. The position sensor is statically attached to the parking lock's housing. When the parking lock's piston moves, the position sensor detects the magnet's movement. The calibrated coordinate system is then permanently stored.

[0017] The operation of the fluid device, as used, for example, in Fig. As shown in Figure 1, the operation of the fluid device is carried out by means of a method proposed in this document, hereinafter also referred to as the control method, which controls, for example, the fluid pump and the switching valve, but also the other valves, and processes data from sensors, such as the displacement sensor.

[0018] The clutch, for example a "closed" or "normally open" clutch, is therefore not actuated by a master cylinder piston, but by a pump actuator which incorporates a fluid pump. When the goal "clutch closing" is requested, for example by a higher-level or other conventional control system, the relief valve, also referred to as the pressure relief valve, closes. The fluid pump delivers the fluid flow towards the slave cylinder piston of the CSC (Concentric Slave Cylinder) until the pressure, also referred to as the CSC pressure or the actuating fluid pressure of the clutch actuator, reaches a predetermined target pressure. Subsequently, if required, the CSC pressure can be maintained for a desired period of time. To release the CSC pressure, the pressure relief valve opens completely.For this purpose, the pressure relief valve is no longer energized and the pressure relief valve opens automatically, for example by means of a spring mechanism.

[0019] The parking lock is actuated by the fluid pump of the pump actuator SHA when the switching valve is energized. Actuation is either displacement-controlled or regulated. As soon as the control unit LCU requests parking lock actuation (the parking lock is to be engaged by the fluid pump against the action of the return spring), the switching valve switches to the parking lock position and the pump begins pumping towards the parking lock. This builds up pressure, and the parking lock piston, along with the parking lock actuator, moves and opens the parking lock. Once the target state is reached, a mechanical locking mechanism engages, holding the piston in this position. The pump actuator SHA stops pumping and reverses its direction of rotation towards cooling. After the energization is removed, the switching valve moves to the clutch position, and the fluid pressure on the parking lock piston decreases due to the released connection to the fluid reservoir.The parking lock piston or actuator remains in the "disengaged" position ("emergency park") because the mechanical locking mechanism holds the piston in this position. As soon as the LCU (Lightweight Control Unit) signals that the parking lock should return to the "park" position, the mechanical locking mechanism is unlocked via a magnetic actuator, and the parking lock piston or actuator, along with the pawl's actuating mechanism, is moved back into the engaged position ("park") by a return spring.

[0020] In this document, the locking mechanism is also referred to as a locking device, a holding mechanism, or a holding device.

[0021] The terms PARK and "Park" are used synonymously, as are the terms NotPARK or "NotPark".

[0022] Problem:

[0023] To keep the parking lock in the "Emergency Park" position, the parking lock piston or actuator is held in place by this mechanical locking mechanism. Every mechanical component can fail over time, and currently there is no mechanism or method to detect this defect early. If the locking device is defective, jammed, or if the release mechanism unintentionally unlocks immediately due to a fault, the parking lock piston cannot be held in the "Emergency Park" position. This means the parking lock will immediately re-engage (return to the "Park" position). If this occurs while the car is in motion, the parking lock can be mechanically damaged, or the broken-off small parts can cause even greater damage.

[0024] The object of the present invention is to improve conventional control methods for verifying the plausibility of the parking lock's path signal, in particular for detecting errors in the holding mechanism (locking mechanism) or the unlocking device of the parking lock.

[0025] This problem is solved by a method for actuating a fluid device having the features according to claim 1.

[0026] The fluid device can be a hydraulic device. The fluid can be a hydraulic fluid. The fluid can be an oil, in particular a hydraulic oil.

[0027] The vehicle can be a motor vehicle, in particular a hybrid vehicle or electric vehicle.

[0028] The fluid pump can be a gear pump. The fluid pump can be a reversible pump. In its first operating mode, the fluid pump can generate the fluid flow rate required to build up the operating fluid pressure. In its second operating mode, the fluid pump can supply at least one cooling device with a fluid flow rate. The fluid pump can be switchable between the first and second operating modes. The fluid pump can be driven by an electric motor.

[0029] The clutch can be a friction clutch or a dog clutch. The clutch can be a disconnect clutch, in particular a K0 clutch in a hybrid powertrain. The clutch actuation device can have a Concentric Slave Cylinder (CSC) actuation.

[0030] The pressure relief valve can be a drain valve.

[0031] The first pressure relief valve state can correspond to a fully closed pressure relief valve. The second pressure relief valve state can correspond to a fully open pressure relief valve. The third pressure relief valve state differs from both a fully open and a fully closed pressure relief valve state.

[0032] A pressure relief valve may not be provided in the fluid device, at least not to limit the actuating fluid pressure.

[0033] The problem is thus solved by a method for actuating a fluid device in a motor vehicle, comprising at least one switching valve actuated by energizing the vehicle, a fluid pump, and a control unit that controls at least the switching valve and the fluid pump. The fluid pump is connected to the switching valve via a hydraulic pressure line, and the switching valve has two switching positions. A first pressure line branch connects the switching valve to a parking lock actuator for actuating a parking lock, and a second pressure line branch connects it to a clutch actuator for actuating a clutch. The two pressure line branches can be alternately connected to the hydraulic pressure line via the switching valve. The parking lock actuator incorporates a position sensor connected to the control unit.which determines the position of the parking lock actuator of the parking lock operating device, wherein the parking lock is engaged in a "Park" state and is designed for an "Emergency Park" state, and wherein the approach to the "Emergency Park" state is carried out by means of the fluid pump in a first direction of rotation (actuation) against the action of a return spring, and wherein the approach to the "Park" state is carried out by means of the return spring, characterized in that when approaching the "Emergency Park" state, the parking lock actuator engages and is held in a holding device upon reaching the "Emergency Park" state. • even if the switching valve is subsequently switched to the switching valve position “clutch” and the fluid pressure on the parking lock piston of the parking lock actuator decreases due to a released connection to a fluid accumulator and / or (alternatively or additionally) • even if the fluid pump is subsequently switched off or operated in a different direction of rotation (cooling), and where an error is detected if, by means of the distance sensor, a movement of the parking lock actuator in the direction of the state "Park" is detected and a predefined position threshold value "Position_NotPark_Error" is also exceeded.

[0034] In a preferred embodiment of the invention, it is provided that the parking lock actuator engaged in the holding device can be unlocked again by means of an unlocking device controlled by the control unit.

[0035] In a preferred embodiment of the invention, it is provided that an error message is generated and / or an emergency operation of the vehicle is initiated when a fault is detected.

[0036] In a preferred embodiment of the invention, the fault is a fault in the holding device or the unlocking device.

[0037] In a preferred embodiment of the invention, the "Park" state is provided to have a stop.

[0038] In a preferred embodiment of the invention, it is provided that the parking lock is designed to move from the "Park" state to the "Emergency Park" state, wherein the switching valve is switched to the "Parking Lock" position, so that the fluid pump is connected to the parking lock actuator of the parking lock actuating device via the hydraulic pressure line and the switching valve and via the first pressure line branch, and wherein the fluid pump is then activated at a predetermined speed and the parking lock actuator moves towards the "Emergency Park" state.

[0039] In a preferred embodiment of the invention, it is provided that the parking lock is engaged from the "Emergency Park" state to the "Park" state, whereby the switching valve (46) is switched to the "Clutch" position and thereby a drain for the fluid in the parking lock actuator is released, so that the return spring moves the parking lock actuator towards the "Park" state and the fluid is displaced from a parking lock cylinder of the parking lock actuator by means of the parking lock piston.

[0040] In a preferred embodiment of the invention, it is provided that the signals from the displacement sensor are received and evaluated by the control unit.

[0041] In a preferred embodiment of the invention, it is provided that the detection, transmission, reception and evaluation of the signals from the displacement sensor is carried out sufficiently quickly and frequently, for example at a 2ms rate.

[0042] In a preferred embodiment of the invention, it is provided that the approach to the respective state “Park” or “Emergency Park” is carried out by means of the parking lock actuator, the distance sensor and a stored position value (Position_EmergencyPark, Position_Park) assigned to the respective state.

[0043] In a further embodiment of the invention, both states are provided to have a stop (Park: stop and EmergencyPark: holding device) and, when approaching the respective state by means of the parking lock actuator, the stop belonging to the respective state is approached, and the current position value is determined there by means of the displacement sensor and it is checked whether there is a match between the currently determined position value and the stored position value, whereby the currently determined position value is considered plausible if there is a match with the stored position value.

[0044] In a further embodiment of the invention, it is provided that the currently determined position value corresponds to the stored position value if the values ​​match within the error tolerance of the displacement sensor.

[0045] In a further embodiment of the invention, it is provided that an error message is generated and / or an emergency operation of the vehicle is initiated if there is no match between the currently determined position value and the stored position value.

[0046] In a further embodiment of the invention, it is provided that the stored position values ​​of the states “Park” and “NotPark” are determined and stored in an end-of-line procedure in the gearbox factory.

[0047] In a preferred embodiment of the invention, it is provided that the actuation of the parking lock actuator is regulated or controlled away.

[0048] In a further embodiment of the invention, it is provided that the signals from the displacement sensor are received and evaluated by the control unit.

[0049] In a preferred embodiment of the invention, it is provided that the detection, transmission, reception and evaluation of the signals from the displacement sensor is carried out sufficiently quickly and frequently, for example at a 2ms rate.

[0050] This advantageously results in an improvement in the detection of errors at the locking mechanism (holding device) or at the unlocking device of the parking lock.

[0051] Further advantages and advantageous embodiments of the invention will become apparent from the description of the figures and the illustrations.

[0052] The invention is described in detail below with reference to the illustrations. These show, in detail: Fig. 1: A schematic representation of a fluid device with a pump actuator SHA (SmartHydraulicActuator) for carrying out the proposed method. Fig. 2: A schematic concept representation of a bistable parking lock as part of the fluid device according to Fig. 1 for the implementation of the proposed procedure. Fig. 3: Schematic representation of the parking lock operating device 48 including parking lock actuator 420 in "Park" and "Emergency Park" positions according to Fig. 1 and Fig. 2 for the implementation of the proposed procedure. Fig. 4: A preferred embodiment of the proposed method with the parameters relevant for carrying out the proposed method

[0053] Fig. Figure 1 shows a fluid device with a pump actuator SHA (SmartHydraulicActuator) in a specific embodiment of the invention. The fluid device 10 is arranged in a vehicle and is designed as a hydraulic device 12 containing a hydraulic fluid. The fluid device 10 comprises a fluid pump 14, which is driven by an electric motor 16, which in turn is electrically controlled by a motor controller 18.

[0054] The fluid device 10 further comprises an actuating device 20 for a clutch 28, hereinafter referred to as the clutch actuating device 26, which, depending on an actuating fluid pressure p, which is generated by a fluid flow supplied by the fluid pump 14, can be switched between a first actuating state 22, in which the clutch actuating device 26 is actuated (shown here in the dashed area), and a second actuating state 24, in which the clutch actuating device 26 is unactuated. The actuating fluid pressure p is a clutch actuating pressure, which in this document is also referred to as the CSC pressure. The clutch actuating device 26 comprises a CSC actuation, which has a slave cylinder piston 30 that is displaceable depending on the actuating fluid pressure p.

[0055] The fluid flow is drawn from a fluid reservoir 32 by the fluid pump 14. A suction-side filter 34 is arranged between the fluid reservoir 32 and the fluid pump 14. The fluid pump 14 is designed as a reversible pump, which, in a first pumping operation, generates the fluid flow to build up the actuating fluid pressure p, and in a second pumping operation generates a fluid flow to supply other vehicle components, for example, cooling devices 36, in particular for cooling a ring gear 38, a hollow shaft bearing 40, and one or more electric motors 42. The fluid is cooled by a heat exchanger 44.

[0056] An electrically controlled switching valve 46, here a 4 / 2 valve, is arranged between the fluid pump 14 and the clutch actuating device 26. The switching valve 46 controls the fluid flow rate between the fluid pump 14 and the clutch actuating device 26, as well as a parking lock actuating device 48, which is associated with a parking lock device 50.

[0057] The parking lock 50, like the clutch 28, is actuated by the fluid pump 14 of the fluid device 10. The fluid pump 14 provides the required fluid flow rate for actuating the respective system, and the switching valve 46 distributes the fluid flow rate as needed either completely to the parking lock actuating device 48 of the parking lock 50 or completely to the clutch actuating device 26 of the clutch 28, but not to both simultaneously. By default, i.e., in the fault-free, de-energized basic setting determined only by mechanical factors such as springs, the switching valve 46 is in the "clutch" position and not in the "parking lock" position, provided the switching valve 46 is not jammed, blocked, or otherwise defective. Therefore, as long as the switching valve 46 is not defective and is not energized, the oil is directed towards the slave cylinder piston 30 of the clutch 28 to engage the clutch.

[0058] The fluid device 10 comprises a controllable pressure relief valve 52, here a 2 / 2-way valve, which is switchable between at least a first relief valve state C1, in which the pressure relief valve 52 is closed, and a second relief valve state C2, in which the pressure relief valve 52 is open. In the first actuation state 22, the pressure relief valve 52 is in the first relief valve state C1, i.e., it is closed. To assume the second actuation state 24, starting from the first actuation state 22, the pressure relief valve 52 is in the second relief valve state C2, i.e., it opens, thereby reducing the actuation fluid pressure p and opening the coupling 28.In the first actuation state 22, the clutch 28 is closed, and the actuating fluid pressure p remains above a certain initial actuation pressure value due to the closed pressure relief valve 52. The check valve 54 prevents backflow of the fluid into the fluid reservoir 32 and a decrease in the actuating fluid pressure p. Temperature fluctuations can cause increases in the actuating fluid pressure p.

[0059] Parking barrier 50 is switched from the "Emergency Park" state to the "Park" state (as in Fig. 1 as well as Fig. 2 shown), by switching the switching valve 46 into the "clutch" position and thereby releasing a drain to the fluid reservoir 32 for the fluid of the parking lock actuator 420, so that the parking lock actuator 420 is moved by the action of the return spring 300 and the fluid is displaced from the parking lock cylinder of the parking lock actuator 420 by means of the parking lock piston 370 and a return flow of the fluid into the fluid reservoir 32 occurs.

[0060] Fig. Figure 2 shows a schematic concept representation of a bistable parking lock as part of the fluid device in the specific embodiment of the invention according to Fig. 1.

[0061] For the sake of simplicity, in this document the term "parking lock actuator 420" refers to the actual parking lock piston 370 as well as the components described therein. Fig. 1 and Fig. The connection shown in Figure 2 extends to the actuating mechanism 410 of the pawl 380, whereby the actuating mechanism 410 itself is no longer included in the term "parking lock actuator" 420. The parking lock actuator 420 and the actuating mechanism 410 of the pawl, which is always in contact with it, perform the same movements together in the direction of movement of the parking lock piston 370, so that the position of the parking lock actuator 420 can be determined by means of the displacement sensor 350. This path along which the parking lock actuator 420 can move is referred to as the actuator path. The movement of the parking lock actuator 420 is initiated by a mechanism, such as the return spring 300, and by a hydraulic mechanism 310, whose hydraulic pressure acts on the parking lock piston 370, and which the fluid pump 14 provides via the switching valve 46 for actuating the parking lock actuating device 48 of the parking lock 50.As a rule, the movement of the parking lock actuator 420 results from the establishment of the force equilibrium between the return spring 300 and the hydraulic pressure on the parking lock piston 370 and ends when, for example, a stop or similar is reached.

[0062] Unlike in Fig. 1 and Fig. As shown in Figure 2, when activated, the lifting magnet 340 pulls the locking mechanism 360 out of its "Park" receptacle 330 or "Not Park" receptacle 320 against a spring mechanism 390, depending on which of the two receptacles the locking mechanism 360 is currently in. The positions of the two receptacles 320 and 330 describe the positions of the two stable end positions of the parking lock. Subsequently, the parking lock actuator 420, and thus also the parking lock piston 370, which has the two receptacles 320 and 330, moves relative to the locking mechanism 360 and the lifting magnet 340 along the actuator path towards the position of the other stable end position, caused by a mechanism such as the return spring 300 or by means of the hydraulic mechanism 310, while the lifting magnet 340 remains active. The position is always determined by means of the displacement sensor 350.Only when the other stable end position is reached does the movement of the parking lock actuator 370 come to a halt, with the current position continuing to be determined by the displacement sensor 350. The lifting magnet 340 is then deactivated, and the locking mechanism 360 is moved, for example, by means of the aforementioned spring mechanism 390, into the other receptacle, either "Not Park" 320 or "Park" 330, so that the parking lock actuator 370 is now locked in the other stable end position.

[0063] The invention is equally feasible in the following versions: Fig. 1 and Fig. In the embodiment shown in Figure 2, when the solenoid 340 is deactivated, the spring mechanism 390 pulls the locking mechanism 360 out of either the "Park" receptacle 330 or the "Not Park" receptacle 320, depending on which of the two receptacles the locking mechanism 360 is currently in. The return spring 300 or the hydraulic mechanism 310 then moves the parking lock piston 370, and upon reaching the other stable end position, the movement of the parking lock piston 370 stops, with the current position being determined by the displacement sensor 350. Activating the solenoid 340 then moves the locking mechanism 360 against the action of the spring mechanism 390 into the other receptacle, either "Not Park" 320 or "Park" 330, so that the parking lock piston 370 is now locked in the other stable end position.

[0064] The "Park" position 330 can also be omitted if a stop 500 can be used instead as a stable PARK end position, as also shown in Fig. 2 and exclusively such in Fig. Figure 3 shows that the parking lock piston 370 is in the PARK position at the end of the actuator travel at the stop 500 (minimal extension) and is held in this position by the return spring 300. If the vehicle is to be moved from this safe end position PARK back to the other safe end position, NotPARK, neither the solenoid 340 nor the spring mechanism 390 needs to pull the detent mechanism 360 out of its receptacle. Instead, fluid is pumped into the parking lock cylinder by the hydraulic mechanism 310, and the parking lock piston 370, together with the parking lock actuator 420, is moved along the actuator travel towards the position of the other stable end position, NotPARK.

[0065] Before the transmission is delivered to the customer, the position sensor 350 of the parking lock 400 is calibrated during end-of-line (EOL) testing. This means that the raw values ​​of the position sensor 350 are assigned to the physical millimeter values ​​of the parking lock actuator 420 along the actuator's travel. Specifically, the signals from the position sensor 350, when it interacts with the magnet 170 in the parking lock actuator 420, are learned and stored at the two positions of the two stops in the direction of PARK and in the direction of Emergency PARK. This allows these two positions to be approached reproducibly using the signals from the position sensor 350 without colliding with either stop at high speed, as the travel speed is reduced sufficiently in time. Referencing at the respective stop is provided for during normal vehicle operation.A magnet 170 is fixed in the parking lock piston 370 of the parking lock actuator 420 between a press-fit sleeve 160 and a rubber buffer 200. As already explained above, for the sake of simplicity, the term parking lock actuator 420 refers to all elements that are movably arranged relative to the position sensor 350 along the actuator's travel, i.e., for example, the parking lock piston 370, the press-fit sleeve 160, the magnet 170, the rubber buffer, and the actuation 230 of the parking lock device 50. The return spring 300 is not included in the term parking lock actuator 420, nor is the actuating mechanism 410 of the locking pawl 380. Fig. 2, which is in Fig. However, 3 is not shown.

[0066] The position sensor 350 is statically and rigidly attached to the housing 190 of the parking lock 400. When the parking lock piston 370 of the parking lock 400 moves, the position sensor 350 detects the movement of the magnet 170 and also the position of the magnet 170 along the actuator path, based on the signals generated in the position sensor 350 by the interaction with the magnet 170. In this way, the coordinate system is learned and permanently stored; that is, the control system knows the current position of the parking lock piston 370 along the actuator path and also where the stops are located, so that the parking lock actuator 420 does not move into either of the two stops at full operating speed, but rather reduces the travel speed sufficiently beforehand.

[0067] In the "PARK" parking lock position, the parking lock 400 is disengaged, i.e., the fluid from the parking lock actuating device 48 is drained and the fluid pump 14 is not pumping any fluid into the parking lock actuating device 48. The parking lock piston 370 is located in the PARK direction at the end of its actuator travel at the stop 500 (minimal extension) and is held in this position by the return spring 300. Fig. 4. This parking lock position is designated as "Position_Park". This corresponds, by agreement, to the physical zero position. Based on the learned coordinate system, the 350 displacement sensor ideally interprets its signals at this position as 0 mm, provided no displacements such as thermal deformations have occurred since the coordinate system was learned. Because each 350 displacement sensor also has a certain sensor tolerance, the displacement sensor displays 0 mm ± Sensor_Tolerance.

[0068] The EOL (End Of Line) learning process involves approaching both stops sequentially at a low travel speed. The resulting position sensor signal is then identified with a position value, and both values ​​are assigned to each other, for example, stored as a pair. At the position of the Minimal Extension 500 (stop in the direction of PARK), the position sensor signal detected there is identified, for example, with the position 0 mm. At the position of the stop in the direction of NotPARK (engagement of the parking lock actuator 420 into the holding device 140_top or of the locking mechanism 360 into the receptacle 320 for the "Not Park" locking position), the position sensor signal detected there is identified, for example, with the position PosMax mm. PosMax can correspond to the actual physical distance between the two stops. Alternatively, 0% and 100% could be selected as percentages of the travel along the actuator path.The measured position sensor signals along the actuator path between 0 mm and PosMax mm are assigned to the respective positions and stored in pairs. At any given point along the actuator path, the position of that point can be uniquely determined using the measured position sensor signal. Based on this, the position sensor signals and their corresponding position values ​​beyond the two end points (less than 0, greater than PosMax) can also be extrapolated and stored in pairs.

[0069] Fig. Figure 4 shows the proposed procedure with the parameters relevant for its execution: Since the parking lock actuation is controlled or regulated away, the position of the parking lock piston 340 or the parking lock actuator 420 ( Fig. 4: Parking lock position) is constantly monitored along the actuator path. The LCU 18 control unit assumes that before time t1 the parking lock is in the "Park" state (stop 500), since, as in Fig. Figure 4 shows that the target state (“Park”), parking lock position (Position_Park), pump speed (Cooling), and fault status (No Fault) must be confirmed. After the parking lock is to be moved to the target state “Emergency Park” by the control unit LCU 18 at time t1 ( Fig. 4: Target state parking lock), the parking lock piston 340 or the parking lock actuator 420 must move from parking lock position “Position_Park” to position “Position_NotPark” against the action of the return spring 300 ( Fig. 4: Parking lock position). If the parking lock piston 340 or the parking lock actuator 420 has reached this position at time t2, the mechanical locking mechanism 140_top engages if functioning correctly.

[0070] Thanks to the mechanical locking mechanism 140_top, the parking lock piston 340 or parking lock actuator 420, and thus also the parking lock, remain in the parking lock position “Position_NotPark” even after time t2, even after the switching valve 46 changes to the clutch position after its energization has ended and the fluid pressure on the parking lock piston 340 or the parking lock actuator 420 decreases due to the released connection to the fluid accumulator 32 and / or (alternatively or additionally) even after the fluid pump 14 stops pumping in the “actuating” direction ( Fig. 4: Pump speed “Activate”) and turns again towards “Cooling” ( Fig. 4: Pump speed (cooling).

[0071] However, as soon as the proposed method using the position sensor 350, after time t2, after the switching valve 46 has switched to the clutch position after its energization has ended and / or ((alternatively or additionally))after the fluid pump 14 has stopped pumping in the direction of "actuating" and is rotating again in the direction of "cooling", a piston movement of the parking lock piston 340 or the parking lock actuator 420 ( Fig. 4: Parking barrier position) from position “Position_NotPark” towards position “Position_Park” and the position boundary “Position_NotPark_Error” is also crossed, then an error is detected at time t3 ( Fig. 4: Fault status) is detected at the locking mechanism 140_top or at the unlocking device 140_bottom of the parking lock, since in the fault-free, locked state no movement or only a very slight movement, which is at least less than the distance to the position limit “Position_NotPark_Fault”, may be detected. In the event of a fault, the fluid pump 14 receives the request at time t3 to pump continuously towards the parking lock ( Fig. 4: Pump speed (“Activate”), so that the parking lock remains open. At the same time, the vehicle switches to emergency mode and slows down ( Fig. 4: Vehicle speed). If the vehicle has come to a standstill at time t4, the fluid pump 14 should rotate again towards "cooling" ( Fig. 4: Pump speed (cooling).

[0072] Since the positioning of the parking barriers is a criterion of functional safety, the check should take place at least every 2 ms during the period between t2 and t3 in order to ensure a sufficiently fast reaction in case of emergency.

[0073] Immediately after the procedure proposed in this document detects an implausible movement signal from the parking lock, while the locking mechanism 140_above should hold the parking lock actuator 420, and at least there should be no crossing of the position limit “Position_NotPark_Error”, the control unit causes the fluid pump 14 to pump again in the direction of the parking lock ( Fig. 4: Pump speed (“Activate”) and this continuously so that the parking lock can be kept open. Reference symbol list 10 Fluid device 12 Hydraulic device 14 Fluid pump 16 Electric motor 18 Control unit (LCU) 20 Actuating device 22 first actuation state 24 second actuation state 26 Clutch actuation device 28 Clutch 30 slave cylinder pistons 32 fluid storage tanks 34 filters 36 cooling devices 38 ring gear teeth 40 hollow shaft bearings 42 Electric motor 44 heat exchangers 46 Switching valve 48 Parking lock actuation device with return spring 300 and parking lock piston 370 50 Parking Lock Device 52 Pressure relief valve 54 shut-off valve 58 Pressure sensor C1 first relief valve state C2 second relief valve state p Actuating fluid pressure 300 Return spring, spring with effect in the direction of "Park" 310 Hydraulic control with effect in the direction of "Emergency Park" 320 Recording for "Not Park" (parking barrier unlocked) setting on parking barrier actuator 420 330 Recording for "Park" setting (parking barrier closed) on parking barrier actuator 420 340 Lifting magnet of the locking mechanism 360 350 displacement sensor 360° locking mechanism • Snap-in: Inserting the snap-in mechanism into a recording (see 140_above) • Unlocking: Removing the detent from the image (see 140_below) 370 parking lock pistons 380 locking pawl 390 Spring mechanism of the locking mechanism 360 400 parking restrictions 410 Actuating mechanism of the locking pawl 380 420 Parking lock actuator 430 stop 440 End of the "Emergency Parking" area 500 stop: “Minimal Extension” in the direction of “Park” 100 Opening for fluid supply 110 cylinder housings 120 seals 140_bottom unlocking device 140_top Locking mechanism or locking device or holding mechanism or holding device 160 crimp sleeve for magnet 170 Magnet for displacement sensor 190 cases 200 rubber buffers 220 Print 230 Operation of the parking lock unit t1, t2, t3, t4 Time

Claims

[1] Method for actuating a fluid device (10) in a motor vehicle comprising at least one switching valve (46) actuated by energizing it, a fluid pump (14), and a control unit (18) that controls at least the switching valve (46) and the fluid pump (14), wherein the fluid pump (14) is connected to the switching valve (46) via a hydraulic pressure line, and the switching valve (46) has two switching positions and is connected via a first pressure line branch to a parking lock actuator (420) of a parking lock actuating device (48) for actuating a parking lock device (50), and via a second pressure line branch to a clutch actuating device (26) for actuating a clutch (28), wherein the two pressure line branches can be alternately connected to the hydraulic pressure line by means of the switching valve (46), and wherein a position sensor (350) connected to the control unit (18) is located in the parking lock actuating device (48).which determines the position of the parking lock actuator (420) of the parking lock actuating device (48), wherein the parking lock (50) is engaged in a "Park" state and is designed for an "Emergency Park" state, and wherein the "Emergency Park" state is approached by means of the fluid pump (14) in a first direction of rotation (actuating) against the action of a return spring (300), and wherein the "Park" state is approached by means of the return spring (300). characterized by , that when approaching the "Emergency Park" state, the parking lock actuator (420) engages and is held in a holding device (140_top) upon reaching the "Emergency Park" state, • even if the switching valve (46) is subsequently switched to the switching valve position “clutch” and the fluid pressure on the parking lock piston (340) of the parking lock actuator (420) decreases due to a released connection to a fluid accumulator (32) and / or • even if the fluid pump (14) is subsequently switched off or operated in a different direction of rotation (cooling), and an error is detected if a movement of the parking lock actuator (420) in the direction of the "Park" state is detected by means of the displacement sensor (350) and a predefined position threshold value "Position_NotPark_Error" is also exceeded. [2] Method according to claim 1, characterized by , that the parking lock actuator (420) locked into the holding device (140_top) is unlocked by means of an unlocking device (140_bottom) which is controlled by the control unit (18). [3] Method according to any one of the preceding claims, characterized by , that an error message is generated and / or an emergency operation of the vehicle is initiated if a fault is detected. [4] Method according to any one of the preceding claims, characterized by, that the fault is a fault in the holding device (140_top) or the unlocking device (140_bottom). [5] Method according to any one of the preceding claims, characterized by , that the state "Park" has a limit (500). [6] Method according to any one of the preceding claims, characterized by , that the parking lock (50) is set from the state “Park” to the state “EmergencyPark”, whereby the switching valve (46) is switched to the switching valve position “Parking lock”, so that the fluid pump (14) is connected via the hydraulic pressure line and the switching valve (46) and via the first pressure line branch to the parking lock actuator (420) of the parking lock actuating device (48) and wherein the fluid pump (14) is then activated at a predetermined speed and the parking lock actuator (420) moves towards the state “EmergencyPark”. [7] Method according to any one of the preceding claims, characterized by, that the parking lock (50) is engaged from the “Emergency Park” state to the “Park” state, whereby the switching valve (46) is switched to the “Clutch” position and thereby a drain for the fluid in the parking lock actuator (420) is released, so that the return spring (300) moves the parking lock actuator (420) towards the “Park” state and the fluid is displaced from a parking lock cylinder of the parking lock actuator (420) by means of the parking lock piston (370) of the parking lock actuator (420). [8] Method according to any one of the preceding claims, characterized by , that the signals from the distance sensor (350) are received and evaluated by the control unit (18). [9] Method according to any one of the preceding claims, characterized by , that the detection, transmission, reception and evaluation of the signals of the displacement sensor (350) is carried out quickly and frequently enough, for example at a 2ms rate. [10] Method according to any one of the preceding claims, characterized by , that the approach to the respective state “Park” or “NotPark” is carried out by means of the parking lock actuator (420), the distance sensor (350) and a stored position value (Position_NotPark, Position_Park) assigned to the respective state.

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