Vehicle powertrain with a parking lock

Abstract

The invention relates to a vehicle drivetrain with an electric motor (EM) that drives at least one vehicle wheel, and with a parking pawl (PS) whose parking pawl gear (3) is arranged on an output shaft (1) of the vehicle drivetrain in a torque-transmitting manner, and whose pawl (5) is in a locked position in tooth engagement with a tooth gap (L1 to L7) of the parking pawl gear (3). According to the invention, a test unit (15) is associated with the electric motor (EM) by means of which a gap detection (Δt) is performed in a learning routine. L ) is feasible, in which the test unit (15) has a gap rotor rotation angle position (α) corresponding to the tooth gap (L1 to L7). L ) of the electric machine rotor (13) determined.

Description

[0001] The invention relates to a vehicle drive train with a parking lock according to the preamble of claim 1 and a method for detecting at least one tooth gap of a parking lock gear of a parking lock in a vehicle drive train according to claim 9.

[0002] A vehicle drivetrain includes an electric motor that drives at least one vehicle wheel. The vehicle drivetrain also includes a parking pawl, the parking pawl of which is mounted on an output shaft of the vehicle drivetrain in a torque-transmitting manner, and whose pawl is engaged in a locked position with a tooth gap of the parking pawl.

[0003] In such a vehicle powertrain with an electric drive and a positive-locking parking pawl, the parking pawl is engaged in the parking pawl wheel by a spring-loaded actuator when the actuated pawl slides over a protrusion or tooth gap on the parking pawl wheel. However, the parking pawl control unit does not know the location of the tooth gap on the parking pawl wheel. The tooth gaps are also not symmetrically distributed. Either the pawl engages a tooth gap directly (in a tooth-to-tooth position), or it comes into tooth-to-tooth contact with the parking pawl wheel. In this case, the pawl slips into the tooth gap even with slight rolling of the vehicle. The parking pawl-parking pawl pairing is subject to mechanical wear, especially from engagement at speeds above 0 km / h.Today, wear is determined empirically on a test bench and transferred into an integral function on a control unit in the vehicle.

[0004] The parking lock described above presents the following problem: During the engagement process, the vehicle may roll slightly, followed by a jolt. The actual wear or play between the parking lock pawl and wheel cannot be determined while the vehicle is in motion. If the parking lock is under tension, a noticeable and audible vibration will occur in the vehicle when the pawl is disengaged under load.

[0005] DE 10 2023 203 151 A1 discloses a generic vehicle drivetrain with a parking lock. DE 10 2018 109 465 A1 discloses a method for determining the state of a vehicle's parking lock, in which a parking pawl is automatically engaged or disengaged from a parking lock gear by a parking lock actuator. The method includes a plausibility check in which the axial position of a motor shaft of the electric motor of the parking lock actuator can be detected to determine an additional state between the engaged and disengaged parking pawl.

[0006] From DE 10 2023 202 014 B3, a method is known for teaching at least one locking position of a locking actuator relative to an electrically driven element of a vehicle's drivetrain that is to be locked. According to this method, the locked element is pivoted clockwise until a first stop of the locking element against the locked element is reached, and then counterclockwise until a second stop of the locking element against the locked element is reached.

[0007] The object of the invention is to provide a vehicle drive train with a parking lock in which the loss of comfort when engaging and disengaging the parking lock can be reduced compared to the prior art.

[0008] The problem is solved by the features of claim 1 or 9. Preferred embodiments of the invention are disclosed in the dependent claims.

[0009] The invention relates to a vehicle drivetrain with an electric motor that drives at least one vehicle wheel and with a parking pawl, the parking pawl of which is arranged on an output shaft of the vehicle drivetrain in a torque-transmitting manner, and whose pawl, in a locked position, engages with a tooth gap of the parking pawl. According to the invention, the following measures are taken to avoid any loss of comfort for the vehicle occupant when engaging and disengaging the parking pawl: A test unit is assigned to the pulse inverter of the electric motor, by means of which a gap detection can be performed in a learning routine, whereby the test unit determines a gap rotor rotation angle of the electric motor rotor that corresponds to the tooth gap. The determined gap rotor rotation angle of the electric motor rotor can be stored in a database of the test unit.

[0010] The invention relates to a test method for determining the gaps in the parking lock wheel in relation to the rotor position and the clearance between the parking lock pawl and the parking lock wheel. The initial determination should be completed by the end of the vehicle's production. By measuring the clearance in the workshop, the customer can determine the wear condition of the parking lock. This ensures smooth engagement and disengagement of the parking lock. Determining the clearance, and thus the wear, prevents premature failure of the parking lock.

[0011] According to the invention, at the start of the learning routine, the test unit engages the parking lock and drives the electric motor at a test speed. When the electric motor rotates at the test speed, a corresponding test current draw is established if the parking lock wheel is tooth-to-tooth aligned. If an increase in the actual current draw compared to the test current draw is detected, an evaluation module of the test unit concludes that a gap has been detected.

[0012] Such an increase in the actual current consumption results from a movement stop of the pawl against a tooth gap flank.

[0013] If such a gap detection is present, an assignment module of the test unit defines the actual rotor rotation angle, which is established at the time of the increase in actual current consumption, as the gap rotor rotation angle. In order to carry out the process chain described above, the test unit has a measuring device for recording the actual current consumption and a rotation angle sensor for recording the actual rotor rotation angle.

[0014] Preferably, the learning routine includes not only the gap detection described above, but also a backlash measurement. The test unit performs this measurement after the gap detection is complete. The backlash measurement determines the rotational play of the locking pawl within the tooth gap.

[0015] In a technical implementation, backlash measurement comprises the following process steps, according to which - after the pawl has reached a stop against the tooth flank, the test unit drives the electric motor in the opposite direction of rotation at a test speed; - the evaluation module concludes that the pawl has reached a movement stop against an opposing tooth flank when the actual current draw increases again compared to the test current draw; and - if such a movement stop is present, the assignment module defines an actual rotor rotation angle position that is established at the time of the increase in actual current consumption as an opposing rotor rotation angle position.

[0016] To calculate the backlash, the test unit can have a calculation module that determines the backlash from a difference between the gap rotor rotation angle position and the opposite flank rotor rotation angle position, which can preferably be stored in the database.

[0017] In one specific embodiment, the parking lock wheel has at least two circumferentially distributed tooth gaps. In this case, after completion of the learning routine performed with respect to the first tooth gap, a subsequent learning routine is performed with respect to the second tooth gap (or further tooth gaps). In preparation for the subsequent learning routine, the test unit can execute a process chain in which it first disengages the pawl from the first tooth gap and then rotates the parking lock wheel by a rotational angular offset. The subsequent learning routine can then be executed.

[0018] It is preferred that the parking lock wheel is arranged directly on the rotor shaft in a torque-transmitting manner. In this case, no measurement inaccuracies arise due to an interposed gear backlash. To obtain reliable test results, it is also preferred that the learning routine be performed with a vehicle wheel that is not in contact with the road surface, so that the vehicle wheel can rotate without load during the learning routine. Before the learning routine is performed, the test unit must define a zero position for the rotor rotation angle in a coordinate system of the test unit, from which the actual rotor rotation angle positions are recorded.

[0019] An embodiment of the invention is described below with reference to the accompanying figures.

[0020] They show: Fig. Figures 1 to 5 show different views illustrating the inventive method for determining the position of the tooth gaps of the parking lock wheel of a parking lock.

[0021] In the Fig. Figure 1 shows a drive train for a vehicle wheel of a two-track vehicle, indicated to the extent necessary for understanding the invention. The drive train has in the Fig. Figure 1 shows an electric motor EM, whose rotor shaft 1 is in (not shown) drive connection with the vehicle wheel. In an actual embodiment, the rotor shaft 1 is driven via a reduction gear and an axle differential to the two vehicle wheels of one axle of the vehicle. A parking lock PS is also installed in the drive train, which has a parking lock wheel 3 and an actuator-operated pawl 5. The parking lock wheel 3 is mounted on the rotor shaft 1 to transmit torque. In the Fig. In the parking lock PS shown, a regular locking process occurs when the vehicle is stationary or at low vehicle speed, i.e., at a low rotational speed of the parking lock wheel 3. During such a locking process, a switching shaft 7 of an actuator 8, with the interposition of an overload spring (not shown), moves the pawl 5 until it is tooth-to-tooth engaged with the parking lock wheel 1. Once tooth-to-tooth engagement is reached, the switching shaft 7 of the actuator 8 is further adjusted to its locked position, building up an overload spring force acting on the pawl 5. As soon as a tooth-to-gap position is established with a small angular displacement, the pawl 5 engages with one of the tooth gaps L1 to L7 of the parking lock wheel 1 as the overload spring force is released.

[0022] In the Fig. 1 The drive train is controlled by means of a central control unit 9, which is in signal connection with the parking lock actuator 8 and with the pulse inverter 11 of the electric machine EM.

[0023] The following will be based on the Fig. Sections 2 to 4 describe a test procedure for determining the corresponding gap-rotor rotation angle α1 to α7 of the rotor 13 of the electric machine EM, corresponding to the respective tooth gap L1 to L7. The test procedure is carried out using a tester 13 that can be connected to the central control unit 9. Furthermore, the test procedure is performed with the vehicle wheel in contact with the road surface, so that the vehicle wheel can rotate without load during the test procedure. A test unit 15, integrated, for example, in the pulse inverter 11, is assigned to the tester 14. The program modules of this unit are shown in the block diagram of the Fig. 3 are only indicated to the extent necessary for understanding the testing procedure. Therefore, in the Fig. 3 does not represent the actual software architecture of the test unit 15 or the tester 14.

[0024] Test unit 15 shows in the Fig. 3 comprises an evaluation module 17, an assignment module 19, a fixed memory or database 21, and a calculation module 31. The evaluation module 17 is connected to a measuring device 23 for measuring the actual current consumption I. ist of the electric machine EM, while the assignment module 19 is in signal connection with a rotary angle sensor 25, which provides an actual rotor rotary angle position α ist The rotor 13 is detected. A gap detection Δt is performed using the test unit 15 in a learning routine. L ( Fig. 4) feasible, in which the gap rotor rotation angle α corresponding to the respective tooth gap L1 to L7 L1 up to αL7 of the electric machine rotor 13 is determined and stored in the database 21 of the test unit 15.

[0025] To start the learning routine, the test unit 15 controls the parking lock PS with a signal S ein to engage the parking lock PS. The test unit 15 then controls the electric motor EM at a test speed n. P on. When operating the electric machine EM at the test speed n P In the case of a tooth-to-tooth position of the parking lock wheel 3, a corresponding test current consumption I is established. P the electric machine EM, which is detected by the measuring device 23.

[0026] The diagram illustrates the following as an example: Fig. 4 indicates a gap detection of the tooth gap L1 of the parking lock wheel 3. Accordingly, the measuring device 23 records an actual current consumption I until shortly before reaching the tooth gap L1. ist , which is the test current consumption I Pcorresponds. In the further course, the locking pawl 5 engages in the tooth gap L1 and strikes it against the tooth gap flank 27 ( Fig. 1), thereby increasing the actual current consumption I ist increases. As soon as the evaluation module 17 of the test unit 15 detects such a significant increase in the actual current consumption I ist compared to the test current consumption I P If this is detected, it indicates a gap detection.

[0027] Once the tooth gap L1 is detected, the assignment module 19 sets the value that is present at the time of the increase in the actual current consumption I. ist Setting actual rotor rotation angle α ist than the gap rotor rotation angle position α L1 fixed. The gap rotor rotation angle α L1 Starting from a rotor rotation angle zero position 0 ( Fig. 2) determined. The rotor rotation angle zero position 0 is defined in a coordinate system in test unit 15 before the learning routine is carried out.

[0028] As can be seen from the diagram of the Fig. As further shown in section 4, the gap detection Δt increases. L the actual current consumption I ist until a threshold value SW is reached. This forms a termination criterion at which the electric machine EM is deactivated.

[0029] After performing the gap detection described above Δt L ( Fig. 4) The test unit 15 starts a backlash measurement Δt for the tooth gap L1. V ( Fig. 5) During backlash measurement Δt V A rotational play v1 of the pawl 5 in the tooth gap L1 is determined. The following process steps are carried out for this purpose, after which - after the pawl 5 reaches its stop against the tooth flank 27, the test unit 15 rotates the electric machine EM in the opposite direction of rotation D2 at the test speed n P targets, - the evaluation module 17 in the event of a renewed increase in the actual current consumption I istcompared to the test current consumption I P on a movement stop of the pawl 5 on a opposite flank 29 of the tooth gap L1; and - if such a movement stop is present, the assignment module 19 will display a value that is present at the time of the increase in the actual current consumption I ist Setting actual rotor rotation angle α ist as an opposite-flank rotor rotation angle position α G1 determines how it is in the Fig. 5 is indicated.

[0030] In a calculation module 31 of the test unit 15, the difference between the gap rotor rotation angle position α is used. L1 and the opposite-flank rotor rotation angle α G1 The twisting action v1 is calculated and stored in database 21.

[0031] Following the learning routine performed for the first gap L1, the same learning routine is performed with reference to the further gaps L2 to L7.

[0032] In preparation for the respective subsequent learning routine, the test unit 15 controls the parking lock PS with a deployment signal S. aus The test unit 15 then activates the electric motor EM to rotate the parking lock wheel 3 by a rotational angular offset, after which the respective subsequent learning routine starts. REFERENCE MARK LIST: 3 parking lock wheel 5 locking pawl 7 shift shaft 8 Actuator 9 central control unit 11 pulse inverters 13 Rotor 14 testers 15 test units 17 Evaluation module 19 Assignment module 21 fixed storage devices 23 Current measuring device 25 Rotation angle sensor 27 Tooth flank 29 Opposite flank 31 Calculation module I ist Actual current consumption I P Test current consumption n P test speed α ist Actual rotor rotation angle α L Gap rotor rotation angle position α G Opposite-flank rotor rotation angle position L1 to L7 gaps between teeth v Twisting game S ein , S aus Control signals PS Parking lock SW threshold D1, D2 directions of rotation 0 Rotor rotation angle zero position Δt L Gap detection Δt V Backlash measurement

Claims

[1] Vehicle drive train with an electric motor (EM) driving at least one vehicle wheel, and with a parking lock (PS) whose parking lock wheel (3) is arranged on an output shaft (1) of the vehicle drive train in a torque-transmitting manner, and whose pawl (5) is in a locking position in tooth engagement with a tooth gap (L1 to L7) of the parking lock wheel (3), wherein the electric motor (EM) is associated with a test unit (15) by means of which a gap detection (Δt) is performed in a learning routine. L ) is feasible, in which the test unit (15) has a gap rotor rotation angle position (α) corresponding to the tooth gap (L1 to L7). L ) of the electric machine rotor (13) determined, characterized by , that To start the learning routine, the test unit (15) engages the parking lock (PS) and starts the electric motor (EM) at a test speed (n). P) controls, in which, in the case of a tooth-to-tooth position of the parking lock wheel (3), a corresponding test current consumption (I) is generated. P ) of the electric motor (EM) sets that an evaluation module (17) of the test unit (15) in the event of an increase in actual current consumption (I ist ) compared to the test current consumption (I P ) concludes that gap detection is possible, and that the increase in actual current consumption (I ist ) as a result of a movement stop of the pawl (5) against a tooth gap flank (27). [2] Vehicle powertrain according to claim 1, characterized by , that if such a gap detection is present, an assignment module (19) of the test unit (15) will display a value that is present at the time of the increase in the actual current consumption (I) ist ) setting actual rotor rotation angle position (α ist ) as the gap rotor rotation angle (α L ) determines. [3] Vehicle powertrain according to claim 1 or 2, characterized by , that the test unit (15) has a measuring device (23) for recording the actual current consumption (I ist ) and a rotation angle sensor (25) for detecting the actual rotor rotation angle position (α ist ) exhibits, and / or that after successful gap detection (Δt L ) the test unit (15) performs a backlash measurement (Δtv) in which a backlash (v) of the pawl (5) in the tooth gap (L1 to L7) can be determined. [4] Vehicle powertrain according to claim 3, characterized by , that the backlash measurement (Δt L ) exhibits the following process steps, after which - after a movement stop of the pawl (5) against the tooth flank (27), the test unit (15) rotates the electric machine (EM) in a counter-rotation direction (D2) at a test speed (n) P ) targets, - the evaluation module (17) in the event of a renewed increase in the actual current consumption (I ist ) compared to the test current consumption (I P) closes on a movement stop of the pawl (5) against a counter tooth flank (29), and - in the event of such a movement stop, the assignment module (19) determines a current consumption that is at the time of the increase in the actual current consumption (I ist ) setting actual rotor rotation angle position (α ist ) as an opposite-flank rotor rotation angle position (α G ) determines. [5] Vehicle powertrain according to claim 4, characterized by , that the test unit (15) has a calculation module (31) which consists of a difference between the gap rotor rotation angle position (α L ) and the opposite-flank rotor rotation angle (α G ) calculates the twisting play (v), which can preferably be stored in the database (21). [6] Vehicle powertrain according to any one of the preceding claims, characterized by, that the parking lock wheel (3) has at least two circumferentially distributed tooth gaps (L1 to L7), and that after completion of the learning routine carried out with reference to the first tooth gap (L1), a subsequent learning routine with reference to the second tooth gap (L2) and to any further tooth gaps (L3 to L7) can be carried out. [7] Vehicle powertrain according to claim 6, characterized by , that in preparation for the subsequent learning routine the test unit (15) disengages the pawl (5) from the first tooth gap (L1) and rotates the parking lock wheel (3) by a rotation angle offset, after which the subsequent learning routine can be carried out. [8] Vehicle powertrain according to any of the preceding claims, characterized by , that the parking lock wheel (3) is arranged directly on the rotor shaft (1), and / or that The learning routine can be performed on a vehicle wheel that is not in contact with a road surface, so that the vehicle wheel can rotate without load, and / or that Before performing the learning routine, the test unit (15) defines a rotor rotation angle zero position (0) in a coordinate system of the test unit (15), from which the actual rotor rotation angle positions (α) are recorded. ist ). [9] Method for detecting at least one tooth gap (L1 to L7) of a parking lock wheel (3) of a parking lock (PS) in a vehicle drive train according to one of the preceding claims.

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