Procedure for activating a parking lock in a motor vehicle

Abstract

Method for actuating a parking lock (400) in a motor vehicle with a parking lock actuator (370), wherein the parking lock actuator (370) has conductive windings and / or a ferromagnetic component as well as a first and a second receptacle (320, 330), and with a locking mechanism (360) and a lifting magnet (340) which is designed as an electromagnet and can move the locking mechanism (360) out of each of the two receptacles (320, 330), wherein the parking lock (400) can assume a locked, detented state (210) and an unlocked, detented state (220) and is transferred from one state to the other by means of the parking lock actuator (340) by activating the lifting magnet (340) from a first, detented state, the locking mechanism (360) out of the first, detented receptacle (320, 330). 330) is moved and a first current value (40, 95) of the lifting magnet (340) is determined,Subsequently, by moving the parking lock actuator (370) relative to the locking mechanism (360), the second receptacle (330, 320) is moved towards the locking mechanism (360), and a second current value (50, 97) of the lifting magnet (340) is determined, where it comes to a stop, then a third current value (45, 96) of the lifting magnet (340) is determined, the lifting magnet (340) is subsequently deactivated, and the locking mechanism (360) is moved into the second receptacle (330, 320), so that the parking lock (400) is now in the second locked state, characterized in that a movement of the parking lock actuator (370) is considered confirmed if the determined second current value (50, 97) of the lifting magnet (340) is smaller than the first current value (40, 95) and is smaller than the third current value (45, 96).

Description

[0001] The invention relates to a method having the features according to the preamble of claim 1.

[0002] The application area of ​​the invention is a method for detecting the end positions of a bistable parking lock without a position sensor.

[0003] In practice, bistable parking lock actuators are currently used, which have two defined, safe end positions: “Park” (parking lock engaged, parking lock locked) and “Emergency Park” (parking lock deployed, parking lock unlocked).

[0004] The parking lock actuator can be mechanically locked at each of these positions. A so-called solenoid is used to release this mechanical locking mechanism.

[0005] The problem arises from the need to detect these positions in order to provide reliable feedback to the vehicle's higher-level control systems and ensure safe operation of the system. Currently, a displacement sensor is used for this purpose, which requires installation space and incurs costs. The invention eliminates the need for this displacement sensor.

[0006] German patent application DE 10 2022 126 261 B3 discloses that the movement of a valve can be reliably detected by means of back-EMF (reverse induction). Back-EMF manifests itself in a drop in current and voltage as soon as the valve begins to move (see [reference]). Fig. 1)

[0007] A displacement sensor is typically used to detect the position of a bistable parking lock actuator. This sensor is also integrated into the monitoring system. An example of a schematic concept for a bistable parking lock is shown in Fig. 3 shown.

[0008] The invention is based on the objective of presenting a way in which the end positions of a bistable parking lock actuator can be detected without having to use a displacement sensor.

[0009] The problem is solved by a method having the features according to claim 1.

[0010] The inventive method for actuating a parking lock in a motor vehicle with a parking lock actuator provides that the parking lock actuator has conductive windings and / or a ferromagnetic component, as well as a first and a second receptacle, and a locking mechanism and a lifting magnet which is designed as an electromagnet and can move the locking mechanism from either of the two receptacles, wherein the parking lock can assume a locked, detented state and an unlocked, detented state and is transferred from one state to the other by means of the parking lock actuator by starting from a first, detented state, activating the lifting magnet to move the locking mechanism from the first, detented receptacle and thereby determining a first voltage and / or current value of the lifting magnet, subsequently by moving the parking lock actuator relative to the locking mechanism,The second receptacle is moved to the locking mechanism, and a second voltage and / or current value of the lifting magnet is determined. The mechanism then stops there, followed by a third voltage and / or current value of the lifting magnet. The lifting magnet is subsequently deactivated, and the locking mechanism is moved into the second receptacle, so that the parking lock is now in the second locked position. It is intended that a movement of the parking lock actuator is considered confirmed if the determined second voltage and / or current value of the lifting magnet is lower than both the first voltage and / or current value and the third voltage and / or current value.

[0011] In a particularly preferred embodiment of the invention, it is provided that the position of the locked, latched state and the position of the unlocked, latched state are deemed to be confirmed when the movement of the parking lock actuator is deemed to be confirmed and the duration of the movement of the parking lock actuator from the first recording to the second recording relative to the latching mechanism is within a predetermined time interval.

[0012] In a preferred embodiment of the invention, it is provided that the parking lock actuator, which has the two receptacles, is moved relative to the locking mechanism by means of a mechanical and / or a hydraulic mechanism.

[0013] In a preferred embodiment of the invention, the mechanism is a spring device.

[0014] In a preferred embodiment of the invention, it is provided that the parking lock is locked and unlocked by means of a locking pawl actuated by the parking lock actuator.

[0015] In a preferred embodiment of the invention, it is provided that the distance between the conductive windings or the ferromagnetic components of the parking lock actuator and the lifting magnet is sufficiently small so that inductive interaction takes place.

[0016] The advantage of the invention is that the position sensor can be dispensed with for the detection of the two end positions of the parking lock.

[0017] Further advantages and advantageous embodiments of the invention are the subject of the following figures and their description.

[0018] They show in detail: Fig. 1 Control valve: movement of the valve is detected by counter-induction Fig. 2 Schematic representation of the inventive method for actuating a parking lock Fig. 3. Schematic concept representation of a bistable parking barrier

[0019] Unlike in Fig. As shown in Figure 3, according to the present invention, when the lifting magnet 340 is activated, for example against a spring mechanism 390, the locking mechanism 360 is pulled 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 located in, wherein the positions of the two receptacles 320, 330 describe the positions of the two stable end positions of the parking lock, for this purpose the voltage and / or current profile 40, 95 in the active lifting magnet 340 is detected. Subsequently, the parking lock actuator 370, which has the two receptacles 320, 330, moves relative to the locking mechanism 360 and the lifting magnet 340 towards the position of the other stable end position by means of a mechanism 300, such as a spring device or by means of a hydraulic mechanism 310, while the lifting magnet 340 remains active.This results in an inductive interaction between the lifting magnet 340 and the conductive windings and / or the ferromagnetic components that are part of the parking lock actuator 370, which moves relative to the lifting magnet 340. The resulting back-induction causes a drop in the current level 50, 97. For this to occur, the distance between the lifting magnet 340 and the parking lock actuator 370, more precisely between the lifting magnet 340 and the conductive windings and / or the ferromagnetic components of the parking lock actuator 370, must be appropriately chosen. Only when the other stable end position is reached does the movement of the parking lock actuator 370 come to a stop, which, due to the now absent back EMF from the voltage and / or current profile 45, 96 in the still active lifting magnet 340, can be detected according to the invention and thereupon the lifting magnet 340 is deactivated 80, 99 and the locking mechanism 360, for example by means of the abovespring mechanism is moved into the now other receptacle “Not Park” 320 or “Park” 330, so that the parking lock actuator 370 is now locked in the other stable end position 10, 70, 210, 220.

[0020] According to the invention, the principle of back-EMF (back-EMF) is used to detect a start (transition 40 -> 50 or 95 -> 97) and an end (transition 50 -> 45 or 97 -> 96) of the movement of the parking lock 400 when the lifting magnet 340 is active, so that the position sensor can be dispensed with. Assuming that, among other things, the expected time for a movement of the parking lock actuator 370 between the end positions 320, 330 is known with sufficient accuracy and that a jamming of the parking lock actuator 370 between the two end positions 320, 330 can be mechanically ruled out, the two end positions 320, 330 can then be identified and confirmed with diagnoses, for example if the actually measured time for the movement of the actuator 370 of the parking lock between the two end positions 320, 330 corresponds sufficiently accurately to the expected time.

[0021] A schematic representation of a procedure for activating a parking barrier is shown in Fig. Figure 2 shows: At time 10, the parking barrier 400 is in parking position 210 - as shown in Fig. Figure 3 shows the detent 360 in the "park" receptacle 330 for the detent 360, and the locking pawl 380 locks the parking lock 400. A parking lock actuation 20 is then requested. This triggers an activation 30 of the lifting magnet 340. In this lifting magnet 340, an electromagnet, the current is then increased to level 40, at which the detent 360 is released and the parking lock is engaged. Due to the movement 60 of the parking lock 400 and the parking lock actuator 370, which is designed with a sufficient number of conductive windings and / or ferromagnetic components, caused, for example, by mechanical 300 or hydraulic 310, a voltage and current drop 50, 190 occurs in the lifting magnet 340. Fig.Figure 2 shows only the current – ​​which continues until the movement of the parking lock actuator 370 is complete. This current dip 50, 190 is physically caused by the back EMF described above, whereby the conductive windings and / or ferromagnetic components of the parking lock actuator 370, moving relative to the lifting magnet 340, interact inductively with the energized, active lifting magnet, and the movement can thus be detected. The distance between the windings or the ferromagnetic components of the parking lock actuator 370 and the lifting magnet 340 is chosen to be sufficiently small so that the desired inductive interaction occurs with sufficient strength. After completion of the movement, the parking lock is in the unlocked, second of the two bistable states 210 and 70, 220, referred to as "Not Park, locked" 220, 320.Since the parking lock actuator 370 no longer moves, the current rises again to level 45, which corresponds to level 40. The lifting magnet 340 is then switched off (80).

[0022] The locking of the parking lock 340 is analogous to the deployment of the parking lock described above and is initiated from time 90.

[0023] Furthermore, the system behavior can be diagnosed, for example, by knowing the expected time between the end positions 320 and 330. This allows for increased safety by determining, for instance, the duration of the reduced current level 50 caused by movement-induced back-induction. Such diagnoses must always be tailored to the specific technical context, i.e., the concrete design of the parking lock. An example diagnosis could be that a jammed parking lock is diagnosed when no voltage or current drop 50 or 97 is detected, as there is no movement of the parking lock actuator 370.

[0024] Depending on the system concept of the parking lock, further measures may be necessary, such as hydraulic pushing with a pump in the "emergency park" position until the lifting magnet 340 is deactivated, in order to prevent the locking mechanism from being released again. Reference symbol list 10. First stable state of the parking lock: "Park" position, locked. 20 Update Parking barrier deployment requested 30 Activation of the lifting magnet requested 40 Current level in lifting magnets: Detent is released 45 Current level in lifting magnets like 40: Parking lock actuator stops 50 Parking lock is deployed: Interruption in the current of the lifting magnet due to back induction caused by movement of the parking lock actuator 60 Movement of the parking lock, for example hydraulically caused 70 Second stable state of the parking lock: "Not Park" position, locked 80 Switch off the solenoid, detent is engaged 89 Update - Parking lock activation requested 90 Activation of the lifting magnet requested 95 Current level in lifting magnets: Detent is released 96 Current level in lifting magnets like 95: Parking lock actuator stops 97 Parking lock is engaged: Interruption in the current of the lifting magnet due to back induction caused by movement of the parking lock actuator 98 Movement of the parking lock, for example by means of a spring, caused 99 Switch off the solenoid; the detent is engaged. 100 requested status of the parking barrier 110 actual state of the parking barrier 120 “Park” 130 “emergency parking” 140 in transition 150 lifting magnet requirement 160 Lifting magnet current 170 active lifting magnet 180 Lifting magnet inactive 190 Break in the current of the lifting magnet due to back induction, parking lock actuator is moved 200 parking lock actuator travel distance 210 “Park”, resting, parking barrier closed 220 “Not Park”, locked, parking barrier unlocked 230 Time 300 Mechanism for achieving "Park", spring device 310 Hydraulic control for "Emergency Park" 320 Recording for "Not Park" (unlocked) setting on parking barrier actuator 330 Recording for resting position “Park” (closed) at park barrier actuator 340 lifting magnet 350 Displacement sensor (optional due to invention) 360° locking mechanism 370 Parking lock actuators with conductive windings and / or ferromagnetic component 380 locking pawl 390 spring mechanism 400 parking restrictions

Claims

Method for actuating a parking lock (400) in a motor vehicle with a parking lock actuator (370), wherein the parking lock actuator (370) has conductive windings and / or a ferromagnetic component as well as a first and a second receptacle (320, 330), and with a locking mechanism (360) and a lifting magnet (340) which is designed as an electromagnet and can move the locking mechanism (360) out of each of the two receptacles (320, 330), wherein the parking lock (400) can assume a locked, detented state (210) and an unlocked, detented state (220) and is transferred from one state to the other by means of the parking lock actuator (340) by activating the lifting magnet (340) from a first, detented state, the locking mechanism (360) out of the first, detented receptacle (320, 330). 330) is moved and a first current value (40, 95) of the lifting magnet (340) is determined,Subsequently, by moving the parking lock actuator (370) relative to the locking mechanism (360), the second receptacle (330, 320) is moved towards the locking mechanism (360), and a second current value (50, 97) of the lifting magnet (340) is determined, where it comes to a stop, then a third current value (45, 96) of the lifting magnet (340) is determined, the lifting magnet (340) is subsequently deactivated, and the locking mechanism (360) is moved into the second receptacle (330, 320), so that the parking lock (400) is now in the second locked state, characterized in that a movement of the parking lock actuator (370) is considered confirmed if the determined second current value (50, 97) of the lifting magnet (340) is smaller than the first current value (40, 95) and smaller than the third current value (45, 96). Method according to claim 1, characterized in that the position of the locked, latched state (210) and the position of the unlocked, latched state (220) is deemed confirmed when the movement of the parking lock actuator (370) is deemed confirmed and the duration of the movement of the parking lock actuator (370) from the first recording (320, 330) to the second recording (330, 320) relative to the latching mechanism (360) is within a predetermined time interval. Method according to claim 1 or 2, characterized in that the parking lock actuator (370), which has the two receptacles (320, 330), is moved relative to the locking mechanism by means of a mechanism (300) and / or by means of a hydraulic mechanism (310). Method according to any one of the preceding claims 1 to 3, characterized in that the mechanism (300) is a spring device (300). Method according to one of the preceding claims 1 to 4, characterized in that the parking lock (400) is locked and unlocked by means of a locking pawl (380) actuated by the parking lock actuator (370). Method according to one of the preceding claims 1 to 5, characterized in that the distance between the current-conducting windings or the ferromagnetic components of the parking lock actuator (370) and the lifting magnet (340) is sufficiently small to allow inductive interaction.

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