vehicle and method for deploying a parking lock in such a vehicle

Abstract

The invention relates to a vehicle with an electric motor (EM) that drives the vehicle wheels (2) via a drive train, wherein a parking lock (4) with a pawl (5) and a locking wheel (7) is installed in the drive train, wherein in a certain parking situation the engaged pawl (5) becomes tensioned, and wherein, for tension-free disengagement of the parking lock, a central control unit (11) controls the pulse inverter (PWR) of the electric motor (EM) to rotate its rotor shaft (1) in a direction of rotation (D) by a predetermined angle of rotation (α). soll) to rotate, thereby generating a relief torque (M) with which the tension acting on the parking lock (4) can be reduced. According to the invention, the pulse inverter (PWR) is integrated together with a rotor position sensor (15) in a control loop (R). A rotation angle control mode can be implemented by means of the control loop (R) in which the electric machine (EM) is controlled with the relief torque (M).

Description

[0001] The invention relates to a vehicle with a parking lock according to the preamble of claim 1 and to a method for deploying the parking lock according to claim 9.

[0002] A battery-powered vehicle has an electric motor that drives the vehicle's wheels via a drivetrain. The drivetrain incorporates a parking lock with a pawl and a corresponding locking gear. When the parking lock is engaged, the pawl positively engages with the locking gear, preventing the vehicle's wheel from rotating. The torque applied to the parking lock by the locked wheel is transferred via the positive connection between the locking gear and the pawl to a drive module housing and further via the engine mounts to the vehicle body or subframe. In certain parking situations, such as parking on a slope, tension can build up in the parking lock. Therefore, to disengage the pawl from the locking gear, a correspondingly powerful, and thus expensive, parking lock actuator is required that can overcome the frictional force between the pawl and the locking gear.

[0003] Alternatively, in a vehicle of this type, the locking wheel is rotated relative to the pawl so that the pawl can be disengaged with virtually no force. This results in a comfort advantage, as there is no vibration in the drivetrain when the pawl disengages.

[0004] German patent application DE 10 2017 121 007 A1 discloses a method for actuating a parking lock of a motor vehicle, which has a pawl and a cooperating locking wheel. In the event of tension between the pawl and the locking wheel caused by a road incline, a control device initiates a controlled rotation of the locking wheel in order to release the tension during a parking lock deployment process.

[0005] A parking lock is known from DE 10 2017 123 076 A1. To enable deployment of the parking lock under light load, a detection device for position recognition of a locking element of the parking lock and a control device for rotating a parking lock wheel depending on the position of the locking element are provided.

[0006] From DE 10 2014 207 997 A1, a method for deploying a parking barrier is known in which a relief torque is applied to the parking barrier for deployment. The relief torque is applied to the parking barrier by appropriate control.

[0007] The prior art only discloses in general terms a rotation of the locking wheel to release tension in the parking lock, thus enabling stress-free deployment. Therefore, the prior art lacks a concrete technical implementation of how a precise rotation of the locking wheel is to be carried out to relieve the engaged parking lock and allow it to be deployed smoothly.

[0008] The object of the invention is to provide an electrically operated vehicle with a parking lock in which tension in the parking lock can be reduced in a structurally simple and targeted manner in order to ensure a smooth parking lock deployment process.

[0009] The problem is solved by the features of claim 1 or 9. Preferred embodiments of the invention are disclosed in the dependent claims.

[0010] The invention relates to a vehicle with an electric motor that drives the vehicle wheels via a drivetrain. A parking lock with a pawl and a cooperating locking wheel is integrated into the drivetrain. In certain parking situations, such as parking on a slope, tension develops in the engaged parking lock. To ensure a tension-free disengagement process, a central control unit activates the pulse inverter of the electric motor to rotate its rotor shaft by a predetermined angle in one direction. This generates a relieving torque that reduces the tension acting on the parking lock.According to the invention, the following measures are taken to provide a precise relief function that enables a load-free parking lock deployment process: The pulse inverter of the electric machine is integrated into a control loop together with a rotor position sensor, a comparator module, and an actuator module. To relieve the parking lock, the control loop operates in a rotation angle control mode, in which the comparator module generates a torque control variable by comparing the target rotation angle with the actual rotation angle of the rotor shaft detected by the rotor position sensor. Based on this torque control variable, an actuator module of the pulse inverter applies the relief torque to the electric machine. The provision of this control loop allows for precise process control with a correspondingly high control accuracy, enabling the parking lock deployment process to be carried out without a load.

[0011] In a technical implementation, the actuator block can be used to ramp up the relief torque within a range from 0 to a maximum value. The following control process is therefore carried out in the control loop: If there is a difference between the target and actual rotation angles, the actuator block increases the relief torque towards its maximum value until the actual rotation angle matches the target angle in the comparator block. Alternatively, the actuator block increases the relief torque until it reaches its maximum value.

[0012] As soon as the actual rotation angle detected by the rotor position sensor in the comparator module matches the target rotation angle, the pulse inverter generates a torque-free signal. Upon receiving such a torque-free signal, the central control unit activates a parking lock actuator to initiate the parking lock deployment process without a load.

[0013] The above process sequence is performed in a properly functioning rotary angle control mode. In contrast, the following describes aspects of the invention that are relevant in a rotary angle control mode with a fault: In an initial control process occurring in the faulty rotary angle control mode, the actuator can increase the relief torque to its maximum value without achieving a match between the target and actual rotation angles. In this process situation, the pulse inverter detects a fault. Such a fault occurs, for example, if the rotor shaft rotates in the wrong direction or if the rotor position sensor is defective.

[0014] In the event of such a fault, the following process chain can be carried out in the vehicle, after which - the pulse inverter generates the torque-free signal as soon as the relief torque has been increased to its maximum value by means of the actuator; and - when the moment-free signal is present, the control unit activates the parking lock actuator to start the parking lock deployment process.

[0015] This initial setup process may fail. If the initial setup is unsuccessful, a second control process with the opposite direction of rotation is performed. If the second control process also fails to achieve a match between the target and actual rotation angles, the pulse inverter generates a warning message for the driver.

[0016] The following describes signal processing in the vehicle's parking management system that can be performed if the initial control process fails: If the initial control process fails, the parking lock actuator can generate an error signal. This signal then triggers the second control process.

[0017] In one configuration, the fault signal from the parking lock actuator can first be routed to the central control unit, which then controls the pulse inverter accordingly to initiate the secondary control process. Alternatively, for simplified signal processing, the following second configuration is provided: The parking lock actuator can be in direct signal connection with the pulse inverter, i.e., without the central control unit. In this case, the fault signal generated by the parking lock actuator is routed directly to the pulse inverter, bypassing the central control unit.

[0018] In one specific embodiment, the central control unit detects the tension of the engaged parking lock as follows: The central control unit can be in signal communication with a vehicle position sensor. This sensor detects the vehicle's angle of inclination. Based on this detected angle, the central control unit can determine whether the parking lock is engaged or not. Furthermore, the central control unit determines the desired direction of rotation based on the detected angle of inclination.

[0019] Furthermore, the target rotation angle can be stored as a fixed parameter in the pulse inverter or in the central control unit.

[0020] An embodiment of the invention is described below with reference to the accompanying figure, which shows a schematic block diagram illustrating the structure and operation of a parking management system according to the invention.

[0021] The figure shows a rough schematic representation of an electrified axle of a two-track vehicle. The axle has an electric motor EM, which drives power to the two wheels of the axle via a drive train. For this purpose, the electric motor EM, with its rotor shaft 1, is connected to an axle differential via a reduction gear. From each output side of the differential, an output shaft 3 leads to the respective wheel 2. Each of the two wheels 2 is equipped with a wheel brake.

[0022] In the figure, a parking management system PM of the vehicle consists of a parking actuator 6 acting on the right wheel brake in the figure and a parking lock 4, which is made up of a pawl 5 supported on the vehicle body and a locking wheel 7 cooperating with it, which is fixed to the output shaft 3.

[0023] The locking pawl 5 can be engaged or disengaged by means of a parking lock actuator 9. The parking lock actuator 9 can be controlled by a central control unit 11. The central control unit 11 controls the parking lock actuator 9 to engage or disengage the parking lock 4. In the figure, the central control unit 11 is in signal communication with a vehicle position sensor 13, which detects the vehicle's position angle. The central control unit 11 is also in signal communication with a pulse inverter PWR of the electric machine EM.

[0024] In a parking situation, the parking lock 4 is engaged to prevent the parked vehicle from rolling away. As soon as the central control unit 11 detects a request from the driver to disengage the parking lock, it first evaluates, based on the vehicle's tilt angle detected by the vehicle position sensor 13, whether the engaged parking lock 4 is under tension, as is the case, for example, when parking on a slope. If the central control unit 11 detects such tension in the engaged parking lock 9, it controls the pulse inverter PWR of the electric machine EM with a target direction of rotation D, which has been determined in the central control unit 11 based on the vehicle's position. In this way, the rotor shaft 1 is rotated in the direction D with a target angle of rotation α. sollThe rotor is twisted, for example, by a fixed parameter stored in the pulse inverter PWR. This rotor twisting generates a relief torque M, which reduces the stress acting on the parking lock 4.

[0025] A key aspect of the invention lies in the following described technical implementation of a precise control of the rotor shaft 1 of the electric machine EM to ensure a smooth, i.e., torque-free, parking lock deployment process: The pulse inverter PWR comprises a comparator module 17 and an actuator module 19, which, together with a rotor position sensor 15, are integrated into a control loop R. A rotation angle control mode is achievable using the control loop R, in which the comparator module 17 determines the actual rotation angle α by comparing the target rotation angle α with the actual rotation angle α. soll and an actual rotation angle α detected by the rotor position sensor 15 ist The rotor shaft 1 generates a torque control variable y.

[0026] Based on the torque control variable y generated by the comparator module 17, a downstream control module 19 of the pulse inverter PWR controls the electric machine EM with the relief torque M. As indicated in the figure, the control module 19 can adjust the relief torque M within a control range from 0 to a maximum value M. max Drive up in a ramp-like fashion.

[0027] With the control loop R, a control process can be carried out as follows: If there is a difference in the angle of rotation between the target angle of rotation α soll and the actual rotation angle α ist The comparator module 17 generates a torque control variable y, which correlates with the magnitude of the angle of rotation difference. The control module 19, which applies the relief torque M to the electric machine EM, can be controlled by means of the torque control variable y. The control module 19 increases the relief torque M towards its maximum value M. maxuntil the actual rotation angle α is reached in comparator module 17. ist with the target rotation angle α soll comes into agreement.

[0028] As soon as the actual rotation angle α detected by the rotor position sensor 15 is in the comparator module 17 ist with the target rotation angle α soll If the signal matches, the pulse inverter PWR generates a torque-free signal S. M . When the moment-free signal S is present M The central control unit 11 controls the parking lock actuator 9 to start the parking lock deployment process.

[0029] The preceding description describes a control process in a fault-free rotary angle control mode. In contrast, the following describes a faulty rotary angle control mode, which occurs, for example, when the central control unit 11 determines an incorrect target direction of rotation D, or when the rotor position sensor 15 is defective.

[0030] In such a fault case, during an initial control process in rotary angle control mode, the actuator 19 can increase the relief torque M up to the maximum value M. max Start up, without a match with the target rotation angle α soll with the actual rotation angle α ist This is achieved. In this situation, the PM parking management system can carry out the following process chain, after which - the pulse inverter PWR the torque-free signal S M generated as soon as the relief moment M from the actuating block 19 reaches the maximum value M max has been restarted; and - when the moment-free signal S is present M The central control unit 11 controls the parking lock actuator 9 to start the deployment process.

[0031] If this deployment process is unsuccessful, the parking lock actuator 9 generates an error signal S. F, which is routed to the central control unit 11. In response, the central control unit 11 controls the pulse inverter PWR to start a second control process with the reverse direction of rotation. If, even in the second control process, there is no agreement between the target rotation angle α soll and the actual rotation angle α ist When this threshold is reached, the pulse inverter PWR generates a warning message for the driver.

[0032] In the above embodiment, in the event of a fault, the actuator 19 can increase the relief torque M up to the maximum value M in a first control process carried out in rotary angle control mode. max Start up, without a match with the target rotation angle α soll with the actual rotation angle α istThis is achieved. Alternatively, in this situation, the control module 19 can also independently reverse the direction of rotation and attempt to reach the desired target rotation angle against the intended direction of rotation. This architectural alternative saves transmission times on the communication bus. REFERENCE MARK LIST: 1 rotor shaft 2 vehicle wheels 3 Output shaft 4 Parking restrictions 5 locking pawl 6 Parking actuator 7 Locking wheel 9 Parking barrier actuator 11 Central control unit 13 Vehicle position sensor 15 Rotor position sensor 17 Comparator module 19 Control module R control loop α soll Target angle of rotation α ist Actual rotation angle S F Error signal PWR pulse inverter S M Moment-free signal M Relief moment y torque control variable PM Park Management

Claims

[1] Vehicle with an electric motor (EM) which drives the vehicle wheels (2) via a drive train, wherein a parking lock (4) with a pawl (5) and a locking wheel (7) is installed in the drive train, wherein in a certain parking situation the engaged pawl (5) becomes preloaded, and wherein, for a tension-free disengagement of the parking lock, a central control unit (11) controls the pulse inverter (PWR) of the electric motor (EM) to rotate its rotor shaft (1) in a direction of rotation (D) by a predetermined angle of rotation (α) soll ) to twist, thereby generating a relief moment (M) with which the tension acting on the parking lock (4) can be reduced, characterized by , that a comparator module (17) and an actuator module (19) of the pulse inverter (PWR) together with a rotor position sensor (15) are integrated in a control loop (R), and that a rotation angle control mode can be implemented by means of the control loop (R) in which the comparator module (17) determines the rotation angle from a comparison between the target rotation angle (α) soll ) and an actual rotation angle (α) detected by the rotor position sensor (15) ist ) generates a torque control variable (y), on the basis of which a control module (19) of the pulse inverter (PWR) controls the electric machine (EM) with the relief torque (M), and that by means of the actuating block (19) the relief moment (M) in an actuating range from 0 to a maximum value (M max ) can be ramped up, and / or that in a control process, if there is a difference between the target rotation angle (α) soll ) and the actual rotation angle (α ist) the actuating block (19) the relief moment (M) in the direction of maximum value (M max ) ramps up until the actual rotation angle (α) is reached in the comparator module (17). ist ) with the target rotation angle (α soll ) matches, or until the unloading moment (M) reaches its maximum value (M max ) reached. [2] Vehicle according to claim 1, characterized by that the pulse inverter (PWR) provides a torque-free signal (S M ) is generated as soon as the actual rotation angle (α) detected by the rotor position sensor (15) is detected in the comparator module (17). ist ) the target rotation angle (α soll ) corresponds, and that when the moment-free signal (S) is present M ) the central control unit (11) controls a parking lock actuator (9) to start the deployment of the parking lock. [3] Vehicle according to claim 1 or 2, characterized by , that if in an initial control process the actuating block (19) increases the relief moment (M) to the maximum value (M max) starts up without a match with the target rotation angle (α) soll ) with the actual rotation angle (α ist ) is reached, the pulse inverter (PWR) detects a fault, for example, if the rotor shaft (1) is rotated in the wrong direction, or if the rotor position sensor (15) is defective. [4] Vehicle according to claim 3, characterized by that in the event of such an error, the following process chain is feasible, according to which - the pulse inverter (PWR) the torque-free signal (M F ) is generated as soon as the relief moment (M) is increased to the maximum value (M) by means of the actuating block (19). max ) has been restarted; and - when the moment-free signal is present (S M ) the central control unit (11) controls the parking lock actuator (9) to perform the deployment of the parking lock. [5] Vehicle according to claim 4, characterized by, that if the deployment of the parking lock following the initial control process is unsuccessful, a second control process with the reverse direction of rotation is initiated, and that the pulse inverter (PWR) generates a warning message for the driver if there is still no agreement between the target rotation angle (α) in the second control process. soll ) and the actual rotation angle (α ist ) is achieved. [6] Vehicle according to claim 3, 4 or 5, characterized by , that if a parking lock deployment process is unsuccessful after the initial control process, the parking lock actuator (9) will issue an error signal (S F ) generated, on the basis of which the second control process starts, and that in particular the error signal (S F) is conducted from the parking lock actuator (9) to the central control unit (11), which controls the pulse inverter (PWR) accordingly, or that the parking lock actuator (9) is in direct signal connection, i.e. without the central control unit (11) being interposed, with the pulse inverter (PWR), so that the fault signal (S F ) is routed directly to the pulse inverter (PWR) by bypassing the central control unit (11). [7] Vehicle according to any of the preceding claims, characterized by , that the central control unit (11) is in signal communication with a vehicle position sensor (13) which detects a vehicle position angle, and that in particular the central control unit (11) determines on the basis of the detected vehicle position angle whether there is a tension of the engaged parking lock (4). [8] Vehicle according to any of the preceding claims, characterized by , that the target rotation angle (α soll) is stored as a fixed parameter in the pulse inverter (PWR) or in the central control unit (11). [9] Method for laying a parking lock (4) in a vehicle according to any of the preceding claims.

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