Procedure for deploying a parking barrier on a motor vehicle

Abstract

Method for engaging a parking lock of a motor vehicle with an electric drive unit comprising an electric machine having a rotor, an output shaft, and a parking lock device (1), wherein the parking lock device (1) has a parking lock pawl (2) which, in an engaged state, engages a toothing (3) of a parking lock wheel (4) and, in a disengaged state, disengages from the toothing (3), wherein the parking lock wheel (4) is rigidly connected to the output shaft, wherein any existing gradient of the motor vehicle is detected, wherein—if the gradient is negative, a negative torque is applied to the output shaft by operation of the electric machine,—if the gradient is positive, a positive torque is applied to the output shaft by operation of the electric machine, and wherein, during the application of the torque, a rotation angle of the rotor is detected by a rotor position sensor, and then,When a flank change of the parking lock pawl (2) in the toothing (3) of the parking lock wheel (4) is detected, the parking lock pawl (2) is disengaged, and if no flank change is detected and the helix angle is less than or equal to the threshold value, an opposing torque is applied, wherein during the application of the torque a rotor angle gradient of a rotor position sensor of the rotor is observed, and if a flank change is detected, the parking lock pawl (2) is disengaged.

Description

[0001] The invention relates to a method for disengaging a parking lock of a motor vehicle according to the preamble of claim 1.

[0002] Vehicles, especially those with an electric drive unit, are secured against rolling away by an electric parking brake and a parking lock. Due to the design of the parking lock, it is not possible to determine precisely whether the parking lock pawl is loaded or unloaded. Large loads are supported on the parking lock pawl, especially with heavy vehicle and / or trailer weights. When the pawl is disengaged, high forces are required, which are released in pulses, leading to both extreme mechanical stress in the drive and high noise emissions into the passenger compartment.

[0003] DE 10 2014 207 997 A1 describes a method for disengaging a positive parking lock of a vehicle drive train having an electric motor as the traction drive. This method provides for the electric motor to apply a relief torque to the parking lock to disengage the parking lock. Furthermore, a control unit for operating an electric motor as the traction drive of a vehicle drive train with a positive parking lock is described. The control unit is designed to actuate the electric motor to provide a relief torque to the parking brake to disengage the parking lock.

[0004] The invention is based on the object of providing a novel method for disengaging a parking lock of a motor vehicle.

[0005] The object is achieved according to the invention by a method for disengaging a parking lock of a motor vehicle having the features of claim 1.

[0006] Advantageous embodiments of the invention are the subject of the subclaims.

[0007] A method for disengaging a parking lock of a motor vehicle with an electric drive unit having an electric machine is proposed. The electric machine has a rotor, an output, and a parking lock device, wherein the parking lock device has a parking lock pawl which, in an engaged state, engages with a toothing of a parking lock gear and, in a disengaged state, disengages from the toothing, wherein the parking lock gear is fixedly connected to the output. According to the invention, an existing gradient of the motor vehicle is detected by a suitable sensor system, wherein - when the gradient is negative, a negative torque is imposed on the output by operation of the electric machine, - when the gradient is positive, a positive torque is applied to the output by the operation of the electric machine, - whereby during the application of the torque, a rotation angle of the rotor is detected by a rotor position sensor, and then, when a flank change of the parking lock pawl in the toothing of the parking lock gear is detected, the parking lock pawl is disengaged.

[0008] In one embodiment of the invention, if the angle of rotation relative to the applied torque is smaller than a predetermined threshold value, a flank change in the toothing of the parking lock gear is detected.

[0009] In one embodiment of the invention, a threshold value of the pitch angle is or will be set, wherein if a pitch angle of the pitch is greater than the threshold value, a higher torque is impressed, and if the pitch angle is less than or equal to the threshold value, a lower torque is impressed.

[0010] In one embodiment of the invention, if no edge change is detected and the pitch angle is less than or equal to the threshold value, an oppositely directed torque is applied, wherein a rotor angle gradient of a rotor position sensor of the rotor is observed during the application of the torque and then, when an edge change is detected, the parking lock pawl is disengaged.

[0011] In one embodiment of the invention, if no gradient value is available, an edge change is first sought by successively applying a positive and a negative torque from the electric motor to the parking lock pawl. If no edge change is detected, a counter is started and, if necessary, a warning message is triggered to the driver.

[0012] In one embodiment, if the number of error cases exceeds a predetermined threshold, a warning message is issued.

[0013] In one embodiment of the invention, it is provided that if information on the gradient is missing - a positive torque is applied, whereby during the application of the torque a rotation angle of the rotor is detected by a rotor position sensor, - and then, when a flank change of the parking lock pawl is detected in the toothing of the parking lock gear, the parking lock pawl is disengaged, - and then, if no flank angle change is detected, a negative moment is applied, During the application of the negative torque, the angle of rotation of the rotor is detected by the rotor position sensor, and then, when a flank change of the parking lock pawl in the toothing of the parking lock gear is detected, the parking lock pawl is disengaged.

[0014] According to the present invention, a method is proposed which provides gradient observation of the rotor angle and the torque of the electric machine. If the gradient [Nm / °] for a certain angular increment [°] is below a threshold value [for example, 10 Nm / °], a free, unloaded parking lock pawl can be assumed. In other words, the method essentially starts by first determining a preloaded state, whereby the further method steps of the method according to the invention are only necessary if a loaded pawl is detected. The locked state of the parking lock pawl is detected by applying a torque of the electric machine and observing the rotor angle gradient. An unloaded parking lock pawl can be disengaged directly. A loaded parking lock pawl, on the other hand, is first unloaded and then disengaged.This is achieved by applying a torque to the electric motor and observing the rotor angle gradient. It is advantageous to use a gradient signal to apply the torque to the electric motor directly against the slope gradient.

[0015] The solution according to the invention makes it possible to reduce component loads (disengagement impact) and noise when disengaging the parking lock pawl to zero or at least significantly. Furthermore, a significant increase in trailer loads is possible.

[0016] Embodiments of the invention are explained in more detail below with reference to drawings.

[0017] Showing: Fig. 1 is a schematic view of a method for disengaging a parking lock of a motor vehicle depending on a gradient, Fig. 2 a schematic view of an error replacement method, and Fig. 3 a schematic view of a method for disengaging the parking lock independently of the gradient.

[0018] Corresponding parts are provided with the same reference numerals in all figures.

[0019] Fig. 1 is a schematic view of a method for disengaging a parking lock of a motor vehicle with an electric drive unit having an electric machine. The electric machine has a rotor with an output. The motor vehicle further has a parking lock device 1, wherein the parking lock device 1 has a parking lock pawl 2, which, in an engaged state, engages with a toothing 3 of a parking lock gear 4 and, in a disengaged state, releases the parking lock gear 4. The parking lock gear 4 is fixedly connected to the output.

[0020] In the method for disengaging the parking lock, in a step S1, a suitable sensor system is used to detect whether the motor vehicle is on an incline and how steep this incline is.

[0021] If the gradient, i.e. the angle of incline, is negative, for example if the motor vehicle is parked on a slope and is facing downhill in the direction of travel, and disengagement of the parking lock is requested, for example by moving a gear selector lever from a parking position (P) to a driving position (D), then in a step S2 or S3 a negative, i.e. generator, torque is impressed on the output and thus the parking lock gear 4 by operation of the electric machine.

[0022] If the gradient, i.e. the angle of incline, is positive, for example if the motor vehicle is parked on a slope and is oriented uphill in the direction of travel, and disengagement of the parking lock is requested, for example by moving a gear selector lever from a parking position (P) to a driving position (D), then in a step S4 or S5 a positive torque is impressed on the output and thus on the parking lock gear 4 by the operation of the electric machine.

[0023] During the torque application, a rotor rotation angle is detected by a rotor position sensor in a step S6, S7, or S8. If a flank change of the parking lock pawl 2 in the toothing 3 of the parking lock gear 4 is detected, the parking lock pawl 2 is disengaged in a step S9.

[0024] The torque can then be reduced in step S10.

[0025] In one embodiment of the invention, if the angle of rotation relative to the applied torque is smaller than a predetermined threshold value, for example 10 Nm / ° for 30° / 44° electrical, a flank change in the toothing 3 of the parking lock gear 4 is detected.

[0026] In one embodiment of the invention, a threshold value of the pitch angle is defined. If the pitch angle is greater than the threshold value, for example, ±10%, or if an absolute value of the pitch angle is greater than an absolute value of the threshold value, a higher torque, for example, ±3500 Nm, is applied in step S3 or S5. If the pitch angle is less than or equal to the threshold value, for example, ±10%, or if the absolute value of the pitch angle is less than or equal to the absolute value of the threshold value, a lower torque, for example, ±1500 Nm, is applied in step S2 or S4.

[0027] In one embodiment of the invention, if no edge change is detected after the torque has been applied, in particular if the pitch angle is less than or equal to the threshold value or if the absolute value of the pitch angle is less than or equal to the absolute value of the threshold value, an oppositely directed torque, for example at the level of the previously applied lower torque, in particular ±1500 Nm, can be applied in a step S11 or S12. During the application of this torque, a rotor angle gradient of a rotor position sensor of the rotor is observed, and if an edge change is detected in step S8, the parking lock S9 is disengaged. This embodiment of the invention serves to take into account the fact that the detected pitch angle can be erroneous, particularly with small gradients.Therefore, if the application of the unloading torque in one direction has not caused a flank change, it is assumed that the lead angle was incorrectly determined and the unloading torque is applied in the opposite direction.

[0028] Fig. 2 is a schematic view of a fault replacement method that is executed when no edge change was detected in step S8 even after applying a higher torque in one of steps S3 or S5 or after applying an opposite torque in one of steps S11 or S12.

[0029] If no gradient value is available or if it appears to have been incorrectly detected, the torque is reduced in step S13. In step S14, a counter that counts the number of error cases is started, and the parking lock is disengaged in step S15.

[0030] In one embodiment of the invention, if the number of error cases exceeds a predetermined threshold, a warning message is issued to the driver.

[0031] In one embodiment of the invention, a method according to Fig. 1 upstream procedure that can be carried out independently of the gradient. This procedure is shown schematically in Fig. 3. In a step S16, a slight positive torque of, for example, +10 Nm is applied. During the application of the torque, the angle of rotation of the rotor is detected by the rotor position sensor in a step S17. If a flank change of the parking lock pawl 2 in the toothing 3 of the parking lock gear 4 is detected, the parking lock pawl 2 is disengaged in a step S18. If no flank angle change is detected, a slight negative torque of, for example, -10 Nm is applied in a step S19. During the application of the torque, the angle of rotation of the rotor is detected by the rotor position sensor in a step S20. If a flank change of the parking lock pawl 2 in the toothing 3 of the parking lock gear 4 is detected, the parking lock pawl 2 is disengaged in step S18. After step S18, the torque can be reduced in step S21.

[0032] If no edge change is detected after the negative torque has been applied, the procedure can be continued according to Fig. 1, provided that information about the gradient is available. Otherwise, the error replacement procedure according to Fig. 2 be carried out. List of reference symbols 1 parking lock device 2 parking lock pawl 3 Gearing 4 parking lock gear S1 to S21 step QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2014 207 997 A1

[0003]

Claims

[1] Method for disengaging a parking lock of a motor vehicle with an electric drive unit with an electric machine which has a rotor, with an output and with a parking lock device (1), wherein the parking lock device (1) has a parking lock pawl (2) which, in an engaged state, engages in a toothing (3) of a parking lock gear (4) and, in a disengaged state, disengages from the toothing (3), wherein the parking lock gear (4) is firmly connected to the output, characterized by that an existing gradient of the motor vehicle is detected, whereby - when the gradient is negative, a negative torque is imposed on the output by operation of the electric machine, - when the gradient is positive, a positive torque is applied to the output by the operation of the electric machine, - wherein during the application of the torque, a rotation angle of the rotor is detected by a rotor position sensor, and then, when a flank change of the parking lock pawl (2) in the toothing (3) of the parking lock gear (4) is detected, the parking lock pawl (2) is disengaged. [2] Method according to claim 1, characterized by that when the angle of rotation relative to the applied torque is smaller than a predetermined threshold value, a flank change in the toothing (3) of the parking lock gear (4) is detected. [3] Method according to claim 1 or 2, characterized by that a threshold value of the pitch angle is specified, whereby if a pitch angle of the pitch is greater than the threshold value, a higher torque is imposed, and if the pitch angle is less than or equal to the threshold value, a lower torque is imposed. [4] Method according to one of the preceding claims, characterized bythat when no edge change is detected and the pitch angle is less than or equal to the threshold value, an oppositely directed torque is applied, wherein during the application of the torque a rotor angle gradient of a rotor position sensor of the rotor is observed and then, when an edge change is detected, the parking lock pawl (2) is disengaged. [5] Method according to one of the preceding claims, characterized by that if no gradient value is available, an edge change is first sought by successively applying a positive and a negative torque of the electric machine to the parking lock pawl (2), and if no edge change is detected, a counter is started. [6] Method according to claim 5, characterized by that if the number of error cases exceeds a specified threshold, a warning message is issued. [7] Method according to one of the preceding claims, characterized by that in the absence of information on the gradient - a positive torque is applied, whereby during the application of the torque a rotation angle of the rotor is detected by a rotor position sensor, - and then, when a flank change of the parking lock pawl (2) in the toothing (3) of the parking lock gear (4) is detected, the parking lock pawl (2) is disengaged, - and then, if no flank angle change is detected, a negative torque is applied, wherein during the application of the negative torque the angle of rotation of the rotor is detected by the rotor position sensor, and then, if a flank change of the parking lock pawl (2) in the toothing (3) of the parking lock gear (4) is detected, the parking lock pawl (2) is disengaged. [8] Method according to one of the preceding claims, characterized bythat a rotor angle gradient and the torque of the electric machine are observed and then, if the rotor angle gradient is below a threshold value for a specified angle increment, an unloaded state of the parking lock pawl (2) is assumed and the parking lock pawl is directly disengaged.

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