Method and device for determining the clamping force of a brake device of a motor vehicle

Abstract

This invention relates to a method for determining the clamping force (F) of a braking device (9) of a motor vehicle (1). Spann The method wherein the motor vehicle (1) has at least one rotatably mounted wheel (4) and a braking system (8), the braking system (8) having at least one braking device (9) and at least one electric motor (13), wherein the braking device (9) has a braking element torsionally connected to the wheel (4) and at least one brake body pressable against the braking element, wherein the electric motor (13) has a motor winding and a rotatably mounted rotor, wherein the rotor is coupled to the brake body via a transmission device (14) such that a clamping force (F) can be generated by the rotation of the rotor. Spann ), through the clamping force (F) Spann The brake body is pressed against the brake element, where a motor current (I) can be applied to the motor windings. Mot The rotor is rotated by means of a rotation angle of the rotor and / or the distance of movement of the movablely disposed elements of the transmission device (14), and the resulting clamping force (F) is determined based on the rotation angle and / or the distance of movement. Sp The magnitude of ann) is specified here. The motor current (I) is determined according to this specification. Mot The magnitude of ) and according to the motor current (I Mot The magnitude of the clamping force (F) determines the clamping force. Spann The size of the clamping force of a motor vehicle's braking device. Another aspect of the invention relates to a device for determining the clamping force of a motor vehicle's braking equipment.

Description

Technical Field

[0001] The present invention relates to a method for determining the clamping force of a braking device of a motor vehicle, wherein the motor vehicle has at least one rotatably mounted wheel and a braking system, the braking system having at least one braking device and at least one electric motor, wherein the braking device has a braking element torsionally connected to the wheel and at least one brake body pressable against the braking element, wherein the electric motor has a motor winding and a rotatably mounted rotor, wherein the rotor is coupled to the brake body via a transmission device such that a clamping force is generated by rotation of the rotor, the clamping force pressing the brake body against the braking element, wherein the rotor can be rotated by applying a motor current to the motor winding, wherein the rotation angle of the rotor and / or the travel distance of a movably mounted element of the transmission device are determined, and wherein the magnitude of the resulting clamping force is determined based on the rotation angle and / or the travel distance.

[0002] Furthermore, the present invention also relates to a method for operating a motor vehicle.

[0003] Furthermore, the present invention relates to a device for determining clamping force, the device having an evaluator. Background Technology

[0004] Motor vehicles typically have multiple rotatably mounted wheels. To reduce the speed of a motor vehicle, it typically has a braking system with at least one braking device. This braking device is assigned to one of the wheels of the motor vehicle and is designed to generate a frictional braking torque, which reduces the current rotational speed of the wheel. For this purpose, the braking device has a braking element, such as a brake disc, that is torsionally connected to the wheel, and at least one brake body that can press against the braking element. When the brake body presses against the braking element, a frictional braking torque is generated. The braking system preferably has multiple braking devices, each of which is assigned to a different wheel among the wheels.

[0005] Increasingly, for the operation of braking devices, braking systems also include an electric motor with motor windings, particularly multiphase ones, and a rotatably mounted rotor. The rotor is coupled to the brake body via a transmission device, so that the rotation of the rotor generates a clamping force that presses the brake body against the braking element. In other words, the rotation of the rotor is converted into movement of the brake body via the transmission device. The magnitude of the clamping force generated corresponds to the magnitude of the frictional braking torque. The greater the clamping force, the greater the frictional braking torque. The rotor can be rotated by applying motor current to the motor windings.

[0006] Methods for determining the magnitude of the clamping force are known from the prior art. It is known that the clamping force can advantageously regulate the electric motor. It is known here that the rotation angle of the rotor and / or the travel distance of the movably mounted elements of the transmission device are determined. The rotation angle and travel distance correspond to the magnitude of the clamping force. The larger the rotation angle, or travel distance, the greater the clamping force generated. Accordingly, the magnitude of the clamping force is determined based on the rotation angle and / or travel distance. Summary of the Invention

[0007] This invention proposes a method for determining the clamping force of a braking device in a motor vehicle, wherein the motor vehicle has at least one rotatably mounted wheel and a braking system, the braking system having at least one braking device and at least one electric motor, wherein the braking device has a braking element connected to the wheel in a torsional manner and at least one brake body capable of pressing against the braking element, wherein the electric motor has a motor winding and a rotatably mounted rotor, wherein the rotor is coupled to the brake body via a transmission device such that rotation of the rotor generates a clamping force, which presses the brake body against the braking element, wherein the rotor can be rotated by applying a motor current to the motor winding, wherein the rotation angle of the rotor and / or the travel distance of a movably mounted element of the transmission device are determined, and wherein the magnitude of the resulting clamping force is determined based on the rotation angle (φ) and / or the travel distance, characterized in that the magnitude of the motor current is determined, and the magnitude of the clamping force is determined based on the magnitude of the motor current. The method according to the invention has the advantage that the accuracy of determining the magnitude of the resulting clamping force is improved. Therefore, according to the invention, the magnitude of the motor current is determined, and the magnitude of the clamping force is determined based on the magnitude of the motor current. In the case of slippage in the transmission device, considering only the rotation angle and / or travel distance as the absolute rotation angle or travel distance gradually increases leads to inaccuracies in determining the magnitude of the resulting clamping force. This inaccuracy is at least partially compensated for by additionally considering the magnitude of the motor current. The magnitude of the motor current also corresponds to the magnitude of the resulting clamping force, at least at a specific operating point of the electric motor. For example, the clamping force increases with the increase of the motor current. It is preferable to detect or measure the motor current. This can also be understood as determining the motor current. That is, there are also sensor devices constructed for detecting the magnitude of the motor current. As an alternative, it is preferable to detect or measure parameters corresponding to the magnitude of the motor current, such as the motor voltage of the motor windings. The magnitude of the motor current is then determined based on the detected parameters.

[0008] According to a preferred embodiment, the magnitude of the clamping force is determined based on a first characteristic curve, which describes the change of the clamping force with respect to the rotation angle or the travel distance. The clamping force can be accurately determined based on the first characteristic curve. Using the first characteristic curve, corresponding clamping forces can be assigned to multiple rotation angles or travel distances respectively.

[0009] The first characteristic curve is preferably varied according to the determined magnitude of the motor current. This allows for simple consideration of the motor current magnitude in the evaluation process. For example, the slope of the first characteristic curve can be varied according to the determined magnitude of the motor current.

[0010] According to a preferred embodiment, a corrected rotation angle is determined based on both the magnitude of the motor current and a determined rotation angle, wherein the clamping force is determined based on the corrected rotation angle; and / or, a corrected travel distance is determined based both the magnitude of the motor current and a determined travel distance, wherein the clamping force is determined based on the corrected travel distance. That is, the initially determined rotation angle or initially determined travel distance is corrected based on the determined magnitude of the motor current. For example, a correction factor is determined based on the magnitude of the motor current, and the determined rotation angle or determined travel distance is multiplied by the correction factor for correction. Accordingly, the determination of the clamping force is based on the corrected rotation angle or corrected travel distance. For example, the clamping force is determined based on the corrected rotation angle or corrected travel distance using a first characteristic curve.

[0011] According to a preferred embodiment, a current-based clamping force is determined based on the magnitude of the motor current and a second characteristic curve, which describes the change in the clamping force transmission ratio of the braking device with the magnitude of the motor current. The first characteristic curve changes according to the current-based clamping force, and / or the modified rotation angle and / or modified travel distance are determined based on the current-based clamping force. By using the second characteristic curve, the determined magnitude of the motor current is accurately considered when determining the clamping force. The second characteristic curve allows for the assignment of corresponding clamping force transmission ratios to multiple motor current values. Then, for example, it is possible to use an equation...

[0012]

[0013] Determine the clamping force based on the current, where F Spann,I K represents the clamping force based on electric current. F,I Indicates the clamping force transmission ratio and I Mot This indicates the determined motor current.

[0014] Preferably, monitoring for corrections is performed, wherein the first characteristic curve is changed according to the magnitude of the motor current only when corrections are present, and / or, wherein the corrected rotation angle and / or corrected travel distance are determined only when corrections are present. A correction should be understood as a situation in which it can be presumed that the desired improvement in accuracy has been achieved by considering the magnitude of the motor current when determining the magnitude of the resulting clamping force. If no correction is present, it is preferable that the determined magnitude of the motor current is still not considered when determining the magnitude of the resulting clamping force.

[0015] According to a preferred embodiment, a predetermined rotational speed threshold is provided, wherein a correction condition is determined to exist when the rotor rotates at a speed lower than the threshold; and / or, a predetermined travel speed threshold is provided, wherein a correction condition is determined to exist when an element travels at a speed lower than the threshold. It is thus presumed that a correction condition exists when the braking device or electric motor is stationary, i.e., when the state of the braking device and the electric motor no longer changes or changes only slightly. This can be reliably determined using the rotational speed or travel speed.

[0016] Preferably, a current change threshold is predetermined, wherein a correction condition is determined to exist when a motor current change is below the current change threshold. As mentioned above, a correction condition exists when the electric motor is stationary. Therefore, the existence of a correction condition can also be reliably determined based on the motor current change.

[0017] The present invention also relates to a method for operating a motor vehicle, wherein the motor vehicle has at least one rotatably mounted wheel and a braking system, the braking system having at least one braking device and at least one electric motor, wherein the braking device has a braking element torsionally connected to the wheel and at least one brake body pressable against the braking element, wherein the electric motor has a motor winding and a rotatably mounted rotor, wherein the rotor is coupled to the brake body via a transmission device such that rotation of the rotor generates a clamping force, by which the clamping force presses the brake body against the braking element, wherein the rotor can be rotated by applying a motor current to the motor winding, wherein the magnitude of the generated clamping force is determined, and wherein a motor current is applied to the motor winding such that the generated clamping force corresponds to a pre-given rated clamping force. The method for operating the motor vehicle is characterized in that the magnitude of the clamping force is determined by a method for determining the clamping force according to the present invention. This also yields the advantages already mentioned. Other preferred features and combinations thereof are derived from the preceding description.

[0018] The apparatus for determining the clamping force of a braking device of a motor vehicle according to the invention is characterized by an evaluator specifically configured to, when used as prescribed, execute the method for determining the clamping force according to the invention, wherein the motor vehicle has at least one rotatably mounted wheel and a braking system, the braking system having at least one braking device and at least one electric motor, wherein the braking device has a braking element torsionally connected to the wheel and at least one brake body pressable against the braking element, wherein the electric motor has motor windings and a rotatably mounted rotor, wherein the rotor is coupled to the brake body via a transmission device such that rotation of the rotor generates a clamping force, by which the brake body is pressed against the braking element, and wherein the rotor can be rotated by applying a motor current to the motor windings. This also yields the advantages already mentioned. Other preferred features and combinations thereof are derived from the preceding description.

[0019] According to a preferred embodiment, the transmission device is directly coupled to the brake body. In this respect, the movably mounted element of the transmission device, or another movably mounted element, directly abuts against the brake body axially about its axis of movement when the brake device is operated. This eliminates the need for a hydraulic connection between the transmission device and the brake body. For example, the transmission device has a planetary roller drive, wherein the movably mounted element is a planetary roller screw. Typically, different brake devices are assigned to multiple vehicles in a motor vehicle. Preferably, each brake device is assigned a different electric motor and a different transmission device. An evaluator is then constructed to determine the clamping force generated by the different electric motors using the method according to the invention.

[0020] According to another preferred embodiment, the transmission device is coupled to the master brake cylinder of the braking system such that a hydraulic piston movably disposed in the master brake cylinder is actuated when a motor current is applied to the motor windings. The master brake cylinder is fluidly connected to the brake body so that the brake body is pressed against the braking element when the hydraulic piston is actuated. In this respect, the transmission device according to this embodiment is indirectly or indirectly coupled to the brake body. Attached Figure Description

[0021] The invention will now be explained in more detail with reference to the accompanying drawings. Therefore:

[0022] Figure 1 A simplified diagram illustrates a motor vehicle.

[0023] Figure 2 Another motor vehicle is illustrated in a simplified diagram.

[0024] Figure 3 The first characteristic curve is shown.

[0025] Figure 4 The second characteristic curve is shown, and

[0026] Figure 5 A method for determining clamping force is shown. Detailed Implementation

[0027] Figure 1 A simplified diagram of a motor vehicle 1 is shown. The motor vehicle 1 has a front axle 2 and a rear axle 3. The front axle 2 has a first wheel 4 and a second wheel 5 that are rotatably mounted. The rear axle 3 has a third wheel 6 and a fourth wheel 7 that are rotatably mounted.

[0028] The motor vehicle 1 also has a braking system 8. The braking system 8 has a number of braking devices 9, 10, 11, and 12 corresponding to the number of wheels. The braking devices 9, 10, 11, and 12... Figure 1 The diagram is shown schematically only. Different braking devices 9, 10, 11, or 12 of the braking system are assigned to each of wheels 4, 5, 6, and 7. Braking devices 9, 10, 11, and 12 are configured to generate frictional braking torque to reduce the rotational speed of the wheel to which they are assigned. For example, the first braking device 9 is configured to reduce the current rotational speed of the first wheel 4. To this end, the first braking device 9 has a braking element that is torsionally connected to the first wheel 4 and at least one brake body that can be pressed against the braking element. Braking devices 10, 11, and 12 correspond to the first braking device 9 in their design. In this respect, braking devices 10, 11, and 12 also each have a braking element and at least one brake body that can be pressed against the braking element.

[0029] The braking system 8 also includes an electric motor 13. The electric motor 13... Figure 1 The diagram is only schematic. The electric motor 13 has a rotatably mounted rotor and motor windings. Here, a motor current I can be applied to the motor windings. Mot To make the rotor rotate.

[0030] The rotor is coupled to the transmission device 14. The transmission device 14 has at least one movably disposed element and is configured to convert the rotation of the rotor into the movement of the movably disposed element. For example, the transmission device 14 has a lead screw drive for this purpose, which has a rotatably disposed lead screw nut and a movably disposed lead screw.

[0031] The braking system 8 also includes a master brake cylinder 15. Here, the master brake cylinder 15 is configured as a series master brake cylinder 15, so that two hydraulic pistons are movably disposed in the master brake cylinder 15. The rotor is coupled to the master brake cylinder 15 via a transmission device 14, so that the hydraulic pistons can move due to the rotation of the rotor.

[0032] The braking system 8 also includes a hydraulic block 16. The master brake cylinder 15 is fluid-technically connected to the hydraulic block 16 via two input lines 17 and 18. The hydraulic block 16 is fluid-technically connected to the wheel brake cylinders of braking devices 9, 10, 11, and 12 via four output lines 19, 20, 21, and 22. If the hydraulic piston is moved in the operating direction, a clamping force F is generated on the brake body due to the hydraulic fluid present in lines 17, 18, 19, 20, 21, and 22. Spann Through the clamping force F Spann Press the brake body against the corresponding brake element.

[0033] Because the rotor is coupled to the hydraulic piston via transmission device 14, a clamping force is generated by the rotation of the rotor. The magnitude of the clamping force corresponds to the rotor's rotation angle φ and the distance the movable component moves. The larger the rotation angle φ, the greater the clamping force F generated. Spann The larger the clamping force F, the greater the clamping force F generated. Spann The magnitude of the clamping force F corresponds to the magnitude of the friction braking torque. Spann The larger the value, the greater the frictional braking torque.

[0034] The motor vehicle 1 also includes a device 23. This device 23 has a rotation angle sensor 24, which is assigned to the rotor and configured to detect the rotor's rotation angle φ. The device 23 also has a current sensor 25, which is assigned to the motor windings and configured to detect the motor current I flowing through the motor windings. Mot The size of the sensor. In addition, device 23 also has an evaluator 26. The evaluator 26 is connected to the rotation angle sensor 24 and the current sensor 25 in terms of communication technology, thereby providing the evaluator 26 with the detected rotation angle φ and motor current I. Mot The size of the value. The evaluator 26 is constructed to evaluate both the rotor's rotation angle φ and the motor current I. Mot The magnitude of the clamping force F is used to determine the clamping force generated. Spann Size.

[0035] The evaluator 26 is also configured to determine the control signal for the switch of the power electronics for the electric motor 13 and to control the switch according to the control signal. In this respect, the evaluator 26 is configured as a controller 26. If a frictional braking torque is to be generated by the braking devices 9, 10, 11 and 12, the evaluator 26 controls the power electronics of the electric motor 13 in a controlled manner, such that the resulting clamping force F Spann This corresponds to a predetermined rated clamping force. In other words, it applies a motor current I to the motor windings. Mot This results in a clamping force F.Spann This corresponds to a predetermined rated clamping force. For example, this rated clamping force is predetermined by the driver of vehicle 1 operating the brake pedal of vehicle 1.

[0036] Figure 2 Another embodiment of motor vehicle 1 is shown. Figure 2 The design of the braking system 8 in the motor vehicle 1 shown differs from that of the other vehicles. Figure 1 Motor vehicle 1 shown. Figure 2 The motor vehicle shown also has braking devices 9, 10, 11 and 12.

[0037] Figure 2 The braking system 8 of the motor vehicle 1 shown has a number of electric motors 13 corresponding to the number of braking devices 9, 10, 11, and 12. Furthermore, the braking system 8 also has a number of transmission devices 14 corresponding to the number of braking devices 9, 10, 11, and 12. Different electric motors from the electric motors 13 and different transmission devices from the transmission devices 14 are assigned to each braking device 9, 10, 11, and 12.

[0038] The rotor of electric motor 13 is also coupled to the brake bodies of braking devices 9, 10, 11 and 12 via transmission device 14, so that a motor current I is applied to the motor windings of electric motor 13. Mot Able to generate clamping force F respectively Spann The clamping force presses the brake bodies of braking devices 9, 10, 11, and 12 against the corresponding brake elements. Here, the transmission device 14 is directly coupled to the brake body, that is, coupled without the intermediate connection of the master brake cylinder.

[0039] Figure 2 The device 23A of the motor vehicle 1 shown has a number of rotation angle sensors 24 corresponding to the number of electric motors 13, wherein each of the electric motors 13 is assigned a different rotation angle sensor among the rotation angle sensors 24.

[0040] The device 23A also has a number of current sensors 25 corresponding to the number of electric motors 13, wherein a different current sensor is assigned to each of the electric motors 13.

[0041] Rotation angle sensor 24 and current sensor 25 are connected to evaluator 26A in terms of communication technology, so that the rotation angle φ detected by rotation angle sensor 24 and the motor current I detected by current sensor 25 are compared. Mot Provided to evaluator 26A.

[0042] Figure 2The evaluator 26A of the motor vehicle 1 shown is configured to evaluate, on the one hand, the rotation angle φ of the corresponding rotor and on the other hand, the corresponding motor current I. Mot The magnitude is determined by the clamping force F generated by the electric motor 13. Spann Size.

[0043] Furthermore, the controller 26A is configured to determine the control signal for the switch of the power electronics for the electric motor 13 and to control the switch according to the control signal. The evaluator 26A is configured to independently control the electric motor 13. The evaluator 26A controls the power electronics such that the clamping force F generated by the electric motor 13... Spann These correspond to pre-given rated clamping forces, as described above with reference to evaluator 26.

[0044] Figure 3 The first characteristic curve L1 is shown. The first characteristic curve L1 describes the generated clamping force F. Spann The magnitude varies with the rotor's rotation angle φ. From Figure 3 It can be seen that the clamping force F Spann It increases as the rotation angle φ increases.

[0045] Figure 4 The second characteristic curve L2 is shown. The second characteristic curve L2 describes the clamping force transmission ratio K of the braking device. F,I The magnitude varies with the motor current I Mot The changes. From Figure 4 It can be seen that the clamping force transmission ratio K F,I With the motor current I Mot It decreases as it increases.

[0046] As previously stated, the evaluator 26 controls the electric motor 13 to generate a clamping force F. Spann Corresponding to a pre-given rated clamping force, the evaluator 26A controls multiple electric motors 13 to generate a corresponding clamping force F. Spann This corresponds to the pre-given rated clamping force.

[0047] The following is for reference. Figure 5 Describe an advantageous method for determining the resulting clamping force F Spann The method of determining the size. Therefore... Figure 5 The method is illustrated with the aid of a flowchart. The method is exemplarily illustrated with... Figure 1 The evaluator 26 for the motor vehicle 1 shown is described. However, Figure 2 The evaluator 26A of the vehicle 1 shown is also configured to perform the method and determine the clamping force F generated by the electric motor 13. Spann .

[0048] In the first step S1, the rotation angle sensor 24 detects the current rotation angle φ of the rotor. Furthermore, the rotation angle sensor 24 provides the detected rotation angle φ to the evaluator 26.

[0049] In the second step S2, the current sensor 25 detects the motor current I. Mot The size of the motor current I. In addition, the current sensor 25 will transmit the motor current I. Mot The detected size is provided to the evaluator 26.

[0050] Steps S1 and S2 are executed at least consecutively, thereby providing the evaluator 26 with the curve of the change in rotation angle φ and the motor current I. Mot The curve showing the change.

[0051] In the third step S3, the evaluator 26 calculates the motor current I... Mot The magnitude is determined by the second characteristic curve L2 and is related to the motor current I. Mot The size corresponds to the clamping force transmission ratio K F,I Then, in step S3, the evaluator 26 determines the clamping force transmission ratio K based on the established ratio. F,I Using equations Determine the clamping force F based on the current. Spann,I .

[0052] In the fourth step S4, the evaluator 26 checks for any corrections. When the braking devices 9, 10, 11, and 12, and the electric motor 13 are stationary, a correction is inferred. For this purpose, the evaluator 26 pre-sets a speed threshold and a current change threshold. Furthermore, the evaluator 26 determines the rotor speed based on the change curve of the rotation angle φ and the motor current I... Mot The change curve determines the motor current I Mot The motor current change. When the determined rotor speed is below the speed threshold and the determined motor current change is below the current change threshold, the evaluator 26 determines that a correction is needed.

[0053] If the evaluator 26 determines in step S4 that no correction is needed, it proceeds to step S5. Subsequently, in step S5, the evaluator 26 determines the resulting clamping force F based on the rotation angle φ detected in step S1 using the first characteristic curve L1. Spann The magnitude of the motor current I is still not considered here. Mot Size.

[0054] However, if the evaluator 26 determines that a correction is needed in step S4, it proceeds to step S6. Subsequently, in step S6, the evaluator 26 determines the clamping force F based on the current, as determined in step S3. Spann,IThe rotor's current-based rotation angle φ is determined using the first characteristic curve L1. I .

[0055] In the seventh step S7, the evaluator 26 will determine the current-based rotation angle φ determined in step S6. I The rotation angle φ is compared with the rotation angle φ detected in step S1. If the detected rotation angle φ is different from the current-based rotation angle φ... I Then, the evaluator 26 corrects the detected rotation angle φ. That is, the evaluator 26 determines the corrected rotation angle φ. korr For example, if the rotation angle φ is based on the current... I If the rotation angle is smaller than the detected rotation angle φ, then a rotation angle smaller than the detected rotation angle φ is determined as the corrected rotation angle φ. korr .

[0056] Then in step S8, the evaluator 26 evaluates the corrected rotation angle φ. korr The clamping force F generated is determined by using the first characteristic curve L1. Spann .

[0057] The evaluator 26 preferably uses the modified rotation angle φ korr The first characteristic curve L1 is changed. That is, the evaluator 26 determines the revised first characteristic curve. If step S5 is executed again, the evaluator 26 determines the resulting clamping force F based on the detected rotation angle φ using the revised first characteristic curve. Spann .

[0058] As previously stated, the rotation angle φ of the rotor corresponds to the travel distance of the movable element of the transmission device 14. According to another embodiment of the method, the travel distance of this element is detected and replaced by the detected rotation angle φ as the determination of the resulting clamping force F. Spann This forms the basis. Then, for example, using the first characteristic curve L1, which describes the generated clamping force F... Spann The change with the distance the component moves.

Claims

1. A method for determining the clamping force of a braking device for a motor vehicle, wherein the motor vehicle (1) has at least one rotatably mounted wheel (4) and a braking system (8), the braking system (8) having at least one braking device (9) and at least one electric motor (13), wherein the braking device (9) has a braking element connected to the wheel (4) in a torsional manner and at least one brake body pressable against the braking element, wherein the electric motor (13) has a motor winding and a rotatably mounted rotor, wherein the rotor is coupled to the brake body via a transmission device (14) such that rotation of the rotor can generate a clamping force (F). Spann ), through the clamping force (F) Spann The brake body is pressed against the brake element, wherein a motor current (I0) can be applied to the motor windings. Mot The rotor is rotated by means of a rotation angle (φ) of the rotor and / or the distance of movement of the movablely mounted elements of the transmission device (14), and the resulting clamping force (F) is determined based on the rotation angle (φ) and / or the distance of movement. Spann The magnitude of ), wherein the motor current (I) is determined. Mot The magnitude of ) and according to the motor current (I Mot The magnitude of the clamping force (F) determines the clamping force. Spann The size of ) Its features are, On the one hand, according to the motor current (I) Mot The size of the rotation angle (φ) and, on the other hand, the corrected rotation angle (φ) is determined based on the determined rotation angle (φ). korr ), where according to the modified rotation angle (φ) korr Determine the clamping force (F) Spann The size of ); and / or, On the one hand, according to the motor current (I) Mot The magnitude of the clamping force (F) is determined, and on the other hand, a corrected movement distance is determined based on the determined movement distance, wherein the clamping force (F) is determined based on the corrected movement distance. Spann The size of ).

2. The method according to claim 1, characterized in that, The clamping force (F) is determined based on the first characteristic curve (L1). Spann The magnitude of the clamping force (F) is described by the first characteristic curve. Spann The value of the rotation angle (φ) or the distance traveled varies with the rotation angle (φ) or the distance traveled.

3. The method according to claim 2, characterized in that, According to the motor current (I) Mot The magnitude of ) changes the first characteristic curve (L1).

4. The method according to claim 3, characterized in that, According to the motor current (I) Mot The magnitude of the current and the second characteristic curve (L2) are used to determine the current-based clamping force (F). Spann,I The second characteristic curve (L2) describes the clamping force transmission ratio (K) of the braking device (9). F,I ) with the motor current (I Mot The magnitude of the first characteristic curve (L1) varies according to the current-based clamping force (F). Spann,I ) changes, and / or the modified rotation angle (φ) mentioned above. korr ) and / or the modified travel distance based on the current-based clamping force (F Spann,I To determine.

5. The method according to claim 3 or 4, characterized in that, Monitor for any corrections, wherein only if a correction is present is the motor current (I) monitored. Mot The magnitude of ) changes the first characteristic curve (L1), and / or, wherein the corrected rotation angle (φ) is determined only if a correction condition exists. korr (and / or the modified travel distance).

6. The method according to claim 5, characterized in that, A predetermined rotational speed threshold is provided, wherein a correction condition is determined to exist when the rotor rotates at a speed lower than the predetermined rotational speed threshold; and / or, a predetermined movement speed threshold is provided, wherein a correction condition is determined to exist when the element moves at a movement speed lower than the predetermined movement speed threshold.

7. The method according to claim 5, characterized in that, A current change threshold is given in advance, wherein a correction is determined when there is a motor current change below the current change threshold.

8. A method for operating a motor vehicle, wherein the motor vehicle (1) has at least one rotatably mounted wheel (4) and a braking system (8), the braking system (8) having at least one braking device (9) and at least one electric motor (13), wherein the braking device (9) has a braking element torsionally connected to the wheel (4) and at least one brake body pressable against the braking element, wherein the electric motor (13) has a motor winding and a rotatably mounted rotor, wherein the rotor is coupled to the brake body via a transmission device (14) such that rotation of the rotor can generate a clamping force (F). Spann ), through the clamping force (F) Spann The brake body is pressed against the brake element, wherein a motor current (I0) can be applied to the motor windings. Mot The rotor is rotated by a clamping force (F) generated therein. Spann The magnitude of ), and wherein the motor current (I) is applied to the motor windings. Mot ), so that the resulting clamping force (F) Spann Corresponding to a pre-given rated clamping force, characterized in that, The clamping force (F) Spann The size of ) is determined by the method according to any one of claims 1 to 7.

9. A device for determining the clamping force of a braking device of a motor vehicle, wherein the motor vehicle (1) has at least one rotatably mounted wheel (4) and a braking system (8), the braking system (8) having at least one braking device (9) and at least one electric motor (13), wherein the braking device (9) has a braking element connected to the wheel (4) in a torsional manner and at least one brake body pressable against the braking element, wherein the electric motor (13) has a motor winding and a rotatably mounted rotor, wherein the rotor is coupled to the brake body via a transmission device (14) such that rotation of the rotor can generate a clamping force (F). Spann ), through the clamping force (F) Spann The brake body is pressed against the brake element, and a motor current (I) can be applied to the motor windings. Mot To rotate the rotor, characterized in that An evaluator (26, 26A) is specifically configured to perform the method according to any one of claims 1 to 7 when used as specified.

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