Method for actuating a fluid unit in a motor vehicle

Abstract

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

Description

[0001] Method for actuating a fluid device in a motor vehicle

[0002] The invention relates to a method for actuating a fluid device in a motor vehicle according to the preamble of claim 1.

[0003] 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.

[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[0005] The as yet unpublished German patent application DE 10 2023 106 429.0 discloses a method for detecting impermissibly high pressures in a hydraulic cylinder of a parking lock using a displacement sensor.

[0006] The as yet unpublished German patent application DE 10 2022 132 010.3 discloses a method for detecting the end positions of a bistable parking lock without a position sensor.

[0007] The as yet unpublished German patent application DE 10 2023 108 130.6 discloses a method for unlocking a parking lock having a parking lock actuator.

[0008] WO 2023 217 314 discloses a magnet integrated in a sleeve for sensing the position of a hydraulic piston. DE 10 2020 117 020 A1 discloses a parking lock actuation system with a positively engaged locking element and a method for controlling the parking lock actuation system.

[0009] DE 10 2019 118 485 A1 discloses a method for detecting an emergency release of a parking lock.

[0010] DE 10 2019 124 561 A1 discloses an arrangement for deactivating a parking lock of a vehicle.

[0011] 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.

[0012] The fluid device, as shown, for example, in Fig. 1, actuates a parking lock (PL) and a clutch by means of a pump actuator (SHA: Smart Hydraulic Actuator), which incorporates a fluid pump and is part of the fluid device. The pump actuator provides the required fluid flow rate to actuate both systems (parking lock and clutch), and a switching valve distributes the fluid flow rate to 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. Therefore, when the switching valve is energized, the parking lock is actuated via the pump actuator SHA. Actuation is achieved by means of a displacement-dependent control system.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. Once 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 speed of the fluid pump is temperature-dependent. At low temperatures, the speed is correspondingly lower than at high temperatures.

[0013] 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.

[0014] The operation of the fluid device, as shown for example in Fig. 1, is carried out by means of a method for operating the fluid device, 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.

[0015] 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.

[0016] Problem:

[0017] If the magnet comes loose from its seat in the piston of the parking lock, the coordinate system of the displacement sensor shifts.

[0018] This occurs when, due to the rapid and hard impact of the piston on the housing of the parking lock upon reaching the minimum extension (impact towards PARK), the magnet, due to its inertia, continues to move inside the piston towards PARK.

[0019] Due to physical and thermal influences, the press-fit sleeve can loosen from its seat in the parking lock piston over its lifespan. This causes the magnet to move, for example, towards the emergency PARK position. This would also shift the sensor's coordinate system.

[0020] However, since the piston geometry itself does not change physically, but only the coordinate system of the sensor changes, the piston of the parking lock will either make an overtravel when the magnet is moved towards PARK or an undertravel when the magnet is moved towards EmergencyPARK.

[0021] In both cases, the result would be an incorrect path reference for the path-dependent activation of the parking barrier.

[0022] The object of the present invention is to improve the conventional control method for verifying the plausibility of the parking lock's position signal with regard to a displacement of the magnet in the piston. This object is achieved by a method for actuating a fluid device with the features according to claim 1.

[0023] 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.

[0024] The vehicle can be a motor vehicle, in particular a hybrid vehicle or electric vehicle.

[0025] 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.

[0026] The clutch can be a friction clutch or a dog clutch. The clutch can be a disconnect clutch, in particular a knock-out clutch in a hybrid powertrain. The clutch actuation device can have a Concentric Slave Cylinder (CSC) actuation.

[0027] The pressure relief valve can be a drain valve.

[0028] 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.

[0029] A pressure relief valve cannot be provided in the fluid device, at least not for limiting the actuating fluid pressure. The problem is therefore solved by a method for actuating a fluid device in a motor vehicle with at least one switching valve that is actuated by energizing it, a fluid pump, and a control unit that controls at least the switching valve and the fluid pump. It is provided that the fluid pump is connected to the switching valve via a hydraulic pressure line, and the switching valve has two switching positions and is connected via a first pressure line branch to a parking lock actuator of a parking lock actuating device for actuating a parking lock, and via a second pressure line branch to a clutch actuating device for actuating a clutch.wherein the two pressure line branches can be alternately connected to the hydraulic pressure line by means of the switching valve, and wherein a position sensor connected to the control unit, which determines the position of the parking lock actuator of the parking lock actuator, is installed in the parking lock operating device, wherein the parking lock can be engaged in a "Park" state and can be set to an "Emergency Park" state, and wherein the approach to the respective state is effected by means of the parking lock actuator, the position sensor and a stored position value assigned to the respective state, and wherein at least one state has a stop. It is further provided that when approaching a state that has a stop, the parking lock actuator moves to the stop belonging to this state and the current position value is determined and checked there by means of the position sensor.whether the currently determined position value matches the stored position value, whereby the currently determined position value is considered plausible if it matches the stored position value.

[0030] In a preferred embodiment of the invention, it is provided that both states each have a stop 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, wherein the currently determined position value is considered plausible if there is a match with the stored position value.

[0031] In a preferred 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.

[0032] 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 if there is no match between the currently determined position value and the stored position value.

[0033] In a preferred 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.

[0034] In a preferred embodiment of the invention, the parking lock actuator has a magnet which interacts with the displacement sensor, so that a position value is assigned to each of the respective positions of the two stops, position values ​​are also assigned to the positions along the actuator path between the two stops, and position values ​​are also assigned to the positions in extension of the actuator path, beyond the respective stop, and / or the actuation of the parking lock actuator is controlled by the displacement.

[0035] 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, whereby 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.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 is switched to the "Clutch" position and thereby a drain for the fluid in the parking lock actuator is released, so that the parking lock actuator is moved by the action of the return spring and the fluid is displaced from a parking lock cylinder of the parking lock actuator by means of the parking lock piston.

[0036] 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.

[0037] 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.

[0038] Advantageously, this results in an improvement in the plausibility of the parking lock's path signal with regard to a displacement of the magnet in the piston.

[0039] Further advantages and advantageous embodiments of the invention will become apparent from the description of the figures and the illustrations.

[0040] The invention is described in detail below with reference to the illustrations. These show, in detail:

[0041] Figure 1: Fluid device with a pump actuator SHA (SmartHydraulicActuator) in a special embodiment of the invention

[0042] Figure 2: Schematic concept representation of a bistable parking barrier as part of the

[0043] Fluid device in the special embodiment of the invention according to Fig.

[0044] Figure 3: Schematic representation of the parking lock actuation device 48 including parking lock actuator 420 in PARK and Emergency PARK positions in the special embodiment of the invention according to Fig. 1 and Fig. 2.

[0045] Figure 4: Schematic representation of the parking lock actuation device 48 including parking lock actuator 420 in PARK and Emergency PARK positions in the special embodiment of the invention according to Fig. 1, Fig. 2 and Fig. 3, as well as a representation of the displacement of the coordinate system of the displacement sensor 350.

[0046] 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.

[0047] 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 not actuated. 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.

[0048] 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.

[0049] 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.

[0050] The parking lock 50, like the clutch 28, is actuated by the fluid pump 14 of the fluid device 10. The fluid pump 4 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 for engaging the clutch.

[0051] 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.

[0052] The parking lock 50 is engaged from the "Emergency Park" state to the "Park" state (as shown in Figure 1 and Figure 2) by switching the control valve 46 to the "Clutch" position, thereby releasing a drain to the fluid reservoir 32 for the fluid of the parking lock actuator 420, so that the return spring 300 moves the parking lock actuator 420 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 the fluid flows back into the fluid reservoir 32.

[0053] 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.

[0054] For the sake of simplicity, the term "parking lock actuator 420" refers to the actual parking lock piston 370 as well as the connection shown in Figures 1 and 2 up 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 mechanical component, such as the return spring 300, and by a hydraulic mechanism 310, whose hydraulic pressure acts on the parking lock piston 370. This pressure is supplied by the fluid pump 4 via the switching valve 46 to actuate the parking lock actuating device 48 of the parking lock 50. The movement of the parking lock actuator 420 typically results from the establishment of a force equilibrium between the return spring 300 and the hydraulic pressure on the parking lock piston 370 and ends, for example, when a stop or similar point is reached.Unlike the depiction in Figures 1 and 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 a hydraulic mechanism 310, while the lifting magnet 340 remains active. The position is always determined using the 350 displacement sensor.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.

[0055] The invention is also feasible in the embodiment shown in Figures 1 and 2. When the lifting magnet 340 is deactivated, the spring mechanism 390 pulls the locking mechanism 360 out of 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 parking lock piston 370 locks into position, with the current position being determined by the displacement sensor 350. Activating the lifting magnet 340 then moves the locking mechanism 360 against the action of the spring mechanism 390 into the other receptacle, "Not Park" 320 or "Park" 330, so that the parking lock piston 370 is now locked in the other stable end position.

[0056] Figure 3 and Figure 4 show an immediate reaction of the control procedure as soon as the path signal shifts outside the allowed tolerances, for example in the negative direction (direction PARK).

[0057] Before the transmission is delivered to the customer, the position sensor 350 of the parking lock 400 is calibrated during the end-of-line (EOL) check. 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 mounted in the parking lock piston 370 of the parking lock actuator 420 between a crimp sleeve 160 and a rubber buffer 200. As 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 crimp sleeve 160, the magnet 170, the rubber buffer, and the actuation mechanism 230 of the parking lock device 50. The return spring 300 is not included in the term parking lock actuator 420.

[0058] 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.

[0059] In the "PARK" parking lock position, the parking lock 400 is disengaged, meaning the fluid from the parking lock actuating device 48 has been 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. This corresponds, by agreement, to the physical zero position. Based on the learned coordinate system, the displacement sensor 350 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 displacement sensor 350 also has a certain sensor tolerance, the displacement sensor displays 0 mm ± sensor tolerance.

[0060] If the magnet 170 becomes dislodged from its seat in the parking lock piston 370 and shifts, the coordinate system of the displacement sensor 350 shifts. This occurs when, due to the rapid and / or hard impact of the parking lock piston 370 against the housing 190 of the parking lock 400 upon reaching the minimum extension 500 (stop in the PARK direction), the magnet 510, due to its inertia, moves further within the parking lock piston 370, for example, by additionally shifting the press sleeve 515, in the direction of PARK. This results in the displacement sensor 350, when approaching the position of the stop 500, at which it would have determined zero mm ± sensor tolerance without the displacement of the magnet 510, now delivering a negative value of less than 0 mm - sensor tolerance due to the displacement. The control procedure then triggers an error message and an emergency run.If the control procedure did not initiate an emergency run, but instead moved from stop 500 towards the emergency PARK and only stopped when the other stop was reached based on the signals of the position sensor 350 and the displaced magnet 510, as well as the interaction signal between position sensor 350 and magnet 170 stored for the position of the emergency PARK stop (unlocking device 210), then an overrun 520 would occur, which could lead to damage to the unlocking device 210, which at least partially forms the stop, depending on the height of the overrun 520.

[0061] This is illustrated in Figure 4 by the downward-pointing guidelines. As soon as the control system detects a value from the displacement sensor 350 that is less than 0 mm ± sensor tolerance, the error that the magnet 170 has shifted is immediately detected, and an emergency operation is initiated.

[0062] Since the positioning of the parking barriers is a criterion of functional safety, the sensor signal check should take place at least every 2 ms to ensure a sufficiently fast reaction in an emergency.

[0063] Figure 4 shows, in addition to a schematic representation of the parking lock operating device 48 including the parking lock actuator 420 in the PARK and Emergency PARK positions, a representation of how the override or underride occurs when the coordinate system of the position sensor 350 is displaced by a displacement of the magnet 170 relative to the rest of the parking lock actuator 420, in particular relative to the parking lock piston 370 and the actuation 230 of the parking lock device 50. The position sensor 350, which detects the position of the magnet 510, is fixedly connected to the housing 190 of the parking lock 400. Relative to this, the elements referred to in this document as the parking lock actuator 420, which are fixedly connected to each other in their undamaged state, such as the parking lock piston 370, the press sleeve 515, the magnet 510, the rubber buffer 505, and the actuation 230 of the parking lock device 50, move.If magnet 510 shifts within the parking lock piston 370 towards EmergencyPARK, this means that when approaching the position of the stop towards EmergencyPARK, where the displacement sensor 350 would have determined the value PosMax ± Sensor_Tolerance (e.g., as determined during the EOL learning process) without the displacement of magnet 510, it now delivers a positive value greater than PosMax mm + Sensor_Tolerance due to the displacement. The control procedure then triggers an error message and an emergency run. The EOL learning process (EOL: End Of Line) proceeds as follows: both stops are approached sequentially at a low travel speed, and the resulting displacement sensor signal is identified with a position value. Both values ​​are then assigned to each other, for example, stored in pairs.At the position of the Minimal Extension 500 (stop towards PARK), the measured displacement sensor signal is identified, for example, as position 0 mm. At the stop towards Emergency PARK (contact with the unlocking device 210 or the detent mechanism 360), the measured displacement sensor signal is identified, for example, as 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 displacement sensor signals measured 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 measured displacement sensor signal can then be used to uniquely determine the position of that point on the actuator path.Based on this, it is also possible to extrapolate to the position sensor signals and the respective assigned position values ​​beyond the two stops (less than 0, greater than PosMax) and to store these in pairs.

[0064] In normal operation of the vehicle, if a displacement of the magnet occurs, in the sense of damage, in the parking lock piston 370, for example in the direction of PARK (Minimal Extension 500), it would

[0065] • When the PARK stop is approached by the parking lock piston 370, the position values ​​corresponding to the measured displacement sensor signals are below the range of 0 to PosMax, i.e., negative values. This indicates a movement of the magnet towards PARK, and appropriate measures are initiated, at least if the magnitude of the determined negative position values ​​exceeds the sensor tolerance at least once before the PARK stop is reached. • When the NotPARK stop is approached by the parking lock piston 370, the position values ​​corresponding to the measured displacement sensor signals remain below the PosMax value. This indicates a movement of the magnet towards PARK, and appropriate measures are initiated, at least if the difference between the PosMax value and the determined position values ​​remains greater than the sensor tolerance until the NotPARK stop is reached.

[0066] If the magnet shifts, in the sense of being damaged, in the parking lock piston 370, for example in the direction of Emergency PARK, then

[0067] • when the PARK stop is approached by the parking lock piston 370, the position values ​​assigned to the measured displacement sensor signals remain in the positive range, thus indicating a shift of the magnet towards Emergency PARK and initiating appropriate measures, at least if the determined position values ​​remain greater than the sensor tolerance until the PARK stop is reached.

[0068] • When the NotPARK stop is approached by the parking lock piston 370, the position values ​​assigned to the measured displacement sensor signals would remain above the PosMax value, thus indicating a displacement of the magnet towards NotPARK and initiating appropriate measures, at least if the difference between the determined position values ​​and the PosMax value exceeds the sensor tolerance at least once before the NotPARK stop is reached.

[0069] List of reference signs

[0070] 10 Fluid device

[0071] 12 Hydraulic device

[0072] 14 Fluid pump

[0073] 16 Electric motor

[0074] 18 Control unit (LCU)

[0075] 20 Actuating device

[0076] 22 first actuation state

[0077] 24 second actuation state

[0078] 26 Clutch actuation device

[0079] 28 Clutch

[0080] 30 slave cylinder pistons

[0081] 32 fluid storage tanks

[0082] 34 filters

[0083] 36 cooling devices

[0084] 38 ring gear teeth

[0085] 40 hollow shaft bearings

[0086] 42 Electric motor

[0087] 44 heat exchangers

[0088] 46 Switching valve

[0089] 48 Parking lock actuation device with return spring 300 and parking lock piston 370

[0090] 50 Parking Lock Device

[0091] 52 Pressure relief valve

[0092] 54 shut-off valve

[0093] 58 Pressure sensor

[0094] C1 first relief valve state

[0095] C2 second relief valve state

[0096] P Actuating fluid pressure Return spring, spring with action in the "Park" direction

[0097] Hydraulic control with effect in the direction of "Emergency Park"

[0098] Recording for "Not Park" (unlocked) setting on parking barrier actuator 420

[0099] Recording for "Park" (closed) rest position at park lock actuator 420

[0100] Lifting magnet

[0101] Position sensor

[0102] Locking mechanism

[0103] Parking lock piston

[0104] Locking pawl

[0105] spring mechanism

[0106] Parking closure

[0107] Actuating mechanism of the locking pawl 380

[0108] Parking lock actuator

[0109] stop

[0110] End of the "Emergency Parking" area

[0111] Opening for fluid supply

[0112] Cylinder housing

[0113] seal

[0114] Unlocking device

[0115] Press sleeve for magnet

[0116] Magnet for displacement sensor

[0117] Housing

[0118] rubber buffer

[0119] Unlocking device

[0120] Pressure

[0121] Activation of the parking lock unit

[0122] Attack: “Minimal Extension” in the direction of “Park”

[0123] Rubber buffer shifted towards "Park" Magnet shifted towards "Park" Press sleeve Overlap when magnet shifted towards "Park" Normal path when magnet is not shifted The overlap pushes the piston further than intended:

[0124] Risk of collision and breakage of actual piston travel from the sensor's perspective when the magnet is shifted towards "Park" s_Park

[0125] Away

[0126] Time

[0127] + / - Sensor tolerance implausible range Mistake

Claims

Patent 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 operating device (48), wherein the parking lock (50) can be engaged in a "Park" state and can be disengaged in an "Emergency Park" state, and wherein the approach to the respective state is carried out by means of the parking lock actuator (420), the displacement sensor (350) and a stored position value assigned to the respective state, and wherein at least one state has a stop (500), characterized in that when approaching a state which has a stop (500), the stop (500) belonging to this state is approached by means of the parking lock actuator (420) and the current position value is determined there by means of the displacement sensor (350) and it is checked whether there is a match between the currently determined position value and the stored position value, wherein the currently determined position value is considered plausible.if there is a match with the stored position value.

2. Method according to claim 1, characterized in that both states each have a stop and wherein, when approaching the respective state by means of the parking lock actuator (420), the stop belonging to the respective state is approached, and the current position value is determined there by means of the displacement sensor (350) and it is checked whether there is a match between the currently determined position value and the stored position value, wherein the currently determined position value is considered plausible if there is a match with the stored position value.

3. Method according to one of the preceding claims, characterized in that a correspondence between the currently determined position value and the stored position value is given if the values ​​agree within the error tolerance (600) of the displacement sensor (350).

4. Method according to one of the preceding claims, characterized in 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.

5. Method according to one of the preceding claims, characterized in that the stored position values ​​of the states “Park” and “NotPark” are determined and stored in an end-of-line procedure in the gearbox plant.

6. Method according to one of the preceding claims, characterized in that the parking lock actuator (420) has a magnet (170, 510) which interacts with the displacement sensor (350) so that a position value is assigned to each of the respective positions of the two stops, and position values ​​are also assigned to the positions along the actuator path between the two stops, and position values ​​are also assigned to the positions in extension of the actuator path, beyond the respective stop. Value is assigned and / or the operation of the parking lock actuator (420) is controlled away.

7. Method according to one of the preceding claims, characterized in that the parking lock (50) is set from the state “Park” to the state “EmergencyPark”, wherein for this purpose 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 subsequently activated at a predetermined speed and the parking lock actuator (420) moves.

8. Method according to one of the preceding claims, characterized in that the parking lock (50) is engaged from the “Emergency Park” state to the “Park” state, wherein 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 parking lock actuator (420) is moved by the action of the return spring (300) 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).

9. Method according to one of the preceding claims, characterized in that the signals of the displacement sensor (350) are received and evaluated by the control unit (18).

10. Method according to one of the preceding claims, characterized in that the detection, transmission, reception and evaluation of the signals of the displacement sensor (350) is carried out sufficiently quickly and frequently, for example at a 2ms rate.

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