Method for determining wear of brake pads of an electromagnetically actuable brake, and electric motor with electromagnetically actuable brake, and signal electronics system for carrying out a method of this type
Patent Information
- Application Number
- EP2023749098
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-09-14
- Filing Date
- 2023-08-02
- Publication Date
- 2025-07-23
AI Technical Summary
Existing methods for determining wear in electromagnetically actuated brake pads are prone to noise in the measurement signal, making it difficult to precisely determine the drop in coil current when the brake is released, leading to inaccurate wear assessment.
A method that involves detecting the time-dependent current curve after applying voltage to the coil, parameterizing a time-dependent function I(t) to minimize deviation between the detected and idealized current curves, and using this to determine the time of ventilation as a measure of wear, while filtering out noise and monitoring for threshold exceedance.
This approach allows for robust and precise determination of brake pad wear by filtering out noise and accurately measuring the time of ventilation, which correlates with the wear of the brake pads, enabling effective monitoring and prediction of wear levels.
Smart Images
Figure 1.1
Abstract
Description
[0001] Method for determining wear of brake pads of an electromagnetically actuated brake and electric motor with electromagnetically actuated brake and signal electronics for implementing such a method Description: The invention relates to a method for determining wear of brake pads of an electromagnetically actuated brake and to an electric motor with electromagnetically actuated brake and signal electronics for implementing such a method. DE 10147817 A1 discloses a method for determining wear in an electromagnetically actuated brake. However, determining the time derivative of the time-dependent current waveform of the brake coil amplifies a noise component in the measurement signal, so that a drop in the coil current caused when the brake is released cannot be determined precisely.The invention is therefore based on the object of developing a method for determining wear in an electromagnetically actuated brake, wherein the determination should be carried out robustly. According to the invention, this object is achieved by the method according to the features specified in claim 1 and by the electric motor according to the features specified in claim 14.Important features of the method for determining wear of brake pads of an electromagnetically actuated brake are that the brake has a coil that can be energized, wherein after a voltage is applied to the coil, in particular to release the brake, the time-dependent course of the electrical current flowing through the coil is recorded, wherein the values of parameters of a time-dependent function I(t) parameterized with the parameters are changed starting from respective initial values of the parameters until the deviation between the recorded current course and the function I(t) becomes as small as possible, in particular until an optimum of the parameters is found, ISI \ EIDOPAT 02.08.2023 wherein the deviation is determined as a functional of the difference function between the detected current curve and the function I(t) or between a current curve extrapolated from the detected current curve and the function I(t), in particular wherein the value of the difference function at the respective time t is formed as the difference between the function value I(t) assigned at the respective time t and the detected current value or a value extrapolated from the detected current values, wherein a time is determined from the parameters thus found, in particular from the parameters of the optimum. is determined as a measure of wear, in particular - where the measure is monitored for exceeding a predetermined threshold value - and / or where a warning message is issued if the measure exceeds a predetermined threshold value. The advantage here is that an idealized function I(t) is specified which specifies a current curve from a theoretical point of view, and that the recorded current curve, which is therefore subject to noise, can then be fitted or adapted to this idealized current curve. Once the parameters for which the smallest deviation can be determined have been found, the time of ventilation can be clearly determined based on the idealized function. Deviations caused by disturbances can thus be filtered out as best as possible.In this way, a measure of the brake pad wear can be determined, since the release path of the brake armature disc depends on the wear of the brake pads, in particular on their remaining wall thickness. The time of release can be determined by the change in inductance that occurs during release, i.e., when the armature disc is attracted to the coil. However, the time is a measure of the time required to build up a magnetic field, which then accelerates the armature disc and causes it to travel the release path. In further development, the maximum achievable current i. maxnot determined as a parameter by optimization, but by a previously performed measurement. The stationary value of the current after release is determined, which is determined only by the voltage applied to the coil, in particular DC voltage U, and the ohmic resistance R of the coil, in particular as the quotient U / R. The idealized function therefore has as few parameters as possible that are varied during optimization, so that only low computing capacity is required. Preferably, only four parameters need to be varied, in particular the time constant before and after release and the current drop directly present during the release process, i.e. the difference between the current immediately before the armature disk is lifted from the brake pad and the current in the coil immediately after the armature disk hits the magnetic body. Another advantage of the invention is that the wear of the brake can be monitored by recording electrical variables.To determine the degree of wear, a large number of current measurements, i.e., a current curve as a whole, are used. Compared to determining local minima or maxima of the current curve, the invention is considerably more robust. In an advantageous embodiment, the electrical voltage applied to the coil is recorded. The advantage here is that the time zero point is clearly defined. With each repetition of the method, the new time zero point is thus clearly known. Thus, with each subsequent repetition, the degree of wear is currently determined, and an evaluation of the series of wear measures determined in the previous repetitions can also be carried out in order to compensate for statistical fluctuations.In an advantageous embodiment, the functional is - the sum of the absolute values of the difference assigned to a series of points in time, or - the sum of the squares of the difference assigned to a series of points in time. The advantage here is that the sum can be determined quickly and easily. Only the absolute values of the difference between the recorded current measurement and the corresponding value of the idealized function I(t) need to be determined and summed. However, if sufficient computing power is available, the square of the difference can also be used instead of the respective absolute value of the difference.In an advantageous embodiment, - the deviation is formed from or by means of the sum of the absolute values of the differences between the function value I(t) assigned at the respective time t and the recorded current value or a value extrapolated from the recorded current values or - the deviation is formed from or by means of the sum of the squares of the differences between the function value I(t) assigned at the respective time t and the recorded current value or a value extrapolated from the recorded current values. The advantage here is that the deviation can be determined quickly and easily. Only the absolute value of the difference between the measured current value recorded at a time t and the value of the idealized function I(t) assigned at this time needs to be determined. The recorded current curve can also be extrapolated, so that measured current values recorded at times between the measuring times can also be assigned.This means that instead of the recorded current measurements, an extrapolated intermediate value can also be used. In an advantageous embodiment, the application of a voltage to the coil defines the time zero point, in particular t = 0. The advantage here is that the method can be carried out repeatedly over time and that the time zero point is always clearly and unambiguously defined. In this way, the change in the degree of wear can be monitored and it can be predicted when a threshold value for the degree of wear will be exceeded. In an advantageous embodiment, the function I(t) is defined in sections, with a second section following a first section, with the difference between a constant, in particular i. ^^^ , and the function I(t) decays exponentially, with a first time constant λ ^ is effective, whereby in the second section the difference between the constant, in particular ^^^^ − ^^ ^ , where the current value ^^ ^ is the current value recorded immediately at or after the time of ventilation, and the function I(t) decreases exponentially, with a second time constant λ ^ is effective, where the first time constant is greater than the second time constant. The advantage here is that the function is easy to calculate and has as few parameters as possible, although the shape of the curve is not trivial, in particular not composed of purely linear segments. In an advantageous embodiment, the function I(t) is defined piecewise, namely by means of: ^ where ^ ^ the time of ventilation is, λ ^ the time constant before the time of ventilation, λ ^ the time constant after the time of ventilation, ^^ ^ the current value immediately at or after the time of ventilation and i ^^^ the stationary achievable current value, in particular and i ^is the last current value reached before the time of ventilation. The advantage here is that a quick and easy determination of the function value of the idealized function is possible. In an advantageous embodiment, the time as a measure of wear determined according to: where i ^ The last current value reached before the time of ventilation is reached. The advantage here is that after determining the above-mentioned parameters of the function I(t), this function can be clearly defined and therefore the time can be determined. This point in time is characteristic of the release of the brake, i.e., the termination of the frictional contact between the armature disk and the brake pad of the brake pad carrier, which is recognizable by the change in inductance due to the axial approach of the armature disk to the magnetic body, i.e., due to the reduction or disappearance of the air gap between the armature disk and the magnetic body. By means of the method according to the invention, the idealized function is fitted or adjusted to the recorded current curve as well as possible, i.e., with the smallest possible deviation. Since a large number of measuring points can be used, a very good adjustment is possible and thus the point in time can be precisely determined. In an advantageous embodiment, the steady-state current value i ^^^The parameter acting is specified as a fixed value, i.e., not changed. The advantage here is that as few parameters as possible need to be changed to find the optimum. This means that less computational effort is required to find the optimum parameter values. To determine the steady-state achievable current value, a DC voltage is applied at the very beginning of the process, and the then steady-state current value is determined, particularly within the limits of measurement accuracy. Alternatively, the steady-state achievable current value is also fixed, in which case, during brake manufacture, it must be ensured that a predetermined ohmic resistance for the coil is maintained as precisely as possible. In an advantageous embodiment, a ferromagnetic armature disk is moved toward the coil when the brake is released. Before the brake is released, the armature disk is pressed against a brake pad, particularly by a spring element supported on a magnetic body.wherein the magnetic body accommodates the coil or is connected to the coil, in particular wherein the armature disk rests against the magnetic body after release. It is advantageous that the armature disk is moved toward the magnetic body during release and thus also toward the coil accommodated in the magnetic body. In an advantageous embodiment, the brake has a shaft that can be braked by the shaft and is rotatably mounted relative to a magnetic body of the brake, wherein the coil is accommodated in a recess or depression of the magnetic body, wherein a ferromagnetic armature disk is connected to the magnetic body in a rotationally fixed and axially movable manner, wherein a brake pad carrier is connected to the shaft in a rotationally fixed and axially movable manner, in particular by an annular driver being placed onto the shaft and connected to the shaft by means of a keyway, and the driver having external teeth that engage with internal teeth of the brake pad carrier.wherein on the side of the brake pad carrier axially facing away from the armature disk, a braking surface is arranged, which is connected to the magnetic body, wherein the brake pad carrier is arranged axially between the braking surface and the armature disk, wherein the armature disk is arranged axially between the brake pad carrier and the magnetic body, wherein spring elements supported on the magnetic body press on the armature disk, in particular applying a spring force to the armature disk, in particular which is directed axially away from the magnetic body. The advantage here is that in the event of a power failure, the brake is automatically activated, thus increasing safety. In an advantageous embodiment, the modification of the parameters to find the optimum is carried out using a simplex method. The advantage here isthat the optimum can be found easily and with as little computational effort as possible. In an advantageous embodiment, the brake is released after applying a voltage, in particular a direct voltage, to the coil. The advantage here is that the application of the voltage, i.e. the voltage jump from zero volts to a direct voltage value, defines the zero time, and the time span from the zero time to the time of ventilation can be determined exactly. In an advantageous design, the parameters - the time of ventilation, - the time constant λ ^ before the time of ventilation, - the time constant λ ^ after the time of ventilation, - the last reached current value i ^ before the time of ventilation, - the current value ^^ ^ immediately at or after the time of ventilation and / or - the stationary achievable current value i ^^^The advantage here is that the time constants depend on the current inductance and the current values on the wear of the brake pad, since the distance between the armature disk and the magnet body varies depending on the wear. In an advantageous embodiment, the steady-state achievable current value i ^^^ determined by determining, after a ventilation, in particular first, the stationary current value, in particular within the scope of the measurement accuracy, and then the parameters the stationary achievable current value i ^^^ not include in particular, whereby the thus determined steady-state achievable current value i ^^^ , in particular taking into account the DC voltage applied to the coil, the ohmic resistance of the coil is determined, in particular and from this the temperature of the coil, and depending on this the initial values of the parameters, in particular the time constant ( λ ^, l ^). The advantage here is that this determination can be carried out easily right at the beginning of the process. Furthermore, the ohmic resistance and, to a certain extent, the inductance of the coil depend on the temperature, which can be easily and precisely determined by determining the steady-state achievable current value due to the constant applied DC voltage. Important features of the electric motor with an electromagnetically actuated brake and signal electronics for implementing the aforementioned process are that a sensor for detecting the current flowing through the coil is arranged in the electric motor. The advantage here is that the wear of the brake can be monitored by detecting electrical variables. To determine the degree of wear, a large number of current measurements, i.e., a current curve as a whole,used. Compared to determining local minima or maxima of the current profile, the invention is considerably more robust. In an advantageous embodiment, a sensor for detecting the voltage applied to the coil is arranged in the electric motor, wherein the sensor(s) are connected to signal electronics that control and / or adjust the voltage applied to the brake coil, in particular wherein the signal electronics comprises a memory for storing the time-dependent curve of the detected current and / or an evaluation unit. The advantage here is that a detected current curve can be used to determine the parameters and thus the degree of wear. In an advantageous embodiment, the brake comprises a shaft that can be braked by the shaft and is rotatably mounted relative to a magnetic body of the brake, wherein the coil is accommodated in a recess or depression in the magnetic body.wherein a ferromagnetic armature disk is connected to the magnetic body in a rotationally fixed and axially movable manner, wherein a brake pad carrier is connected to the shaft in a rotationally fixed and axially displaceable manner, in particular by an annular driver being placed on the shaft and connected to the shaft by means of a keyway, and the driver having an external toothing which engages with an internal toothing of the brake pad carrier, wherein a braking surface is arranged on the side of the brake pad carrier axially facing away from the armature disk, which braking surface is connected to the magnetic body, wherein the brake pad carrier is arranged axially between the braking surface and the armature disk, wherein the armature disk is arranged axially between the brake pad carrier and the magnetic body, wherein spring elements supported on the magnetic body press on the armature disk, in particular applying a spring force to the armature disk,In particular, one directed axially away from the magnetic body. The advantage here is that the brake engages in the event of a power failure, thus ensuring increased safety. Further advantages arise from the subclaims. The invention is not limited to the combination of features of the claims. Those skilled in the art will recognize further possible combinations of claims and / or individual claim features and / or features of the description and / or the figures, in particular from the task and / or the task posed by comparison with the prior art.
[0002] The invention will now be explained in more detail with reference to schematic illustrations: Figure 1 shows a current profile during the release of a brake assembly according to the invention. Figure 2 schematically shows the method according to the invention for determining the working air gap. As shown in the figures, the current ^(^) measured by a current sensor, which flows through a coil of the brake, increases when a voltage U is applied to a coil of the brake assembly. The time-dependent profile of the voltage applied to the coil is designated U(t). The value of the voltage U(t) changes at time ^ ^from 0 to U. The brake arrangement has a shaft to be braked, in particular the rotor shaft of an electric motor, which is rotatably mounted relative to a housing part, in particular of an electric motor. The energizable coil is accommodated in a magnetic body, in particular in an annular recess of the magnetic body. The magnetic body is detachably connected to the housing part. A ring-shaped driver is placed on the shaft and connected to the shaft in a rotationally fixed manner, in particular by means of a keyway connection. The driver has external teeth, onto which a disk-shaped brake pad carrier with its internal teeth is placed, wherein the internal teeth engage with the external teeth, such that the brake pad carrier is connected to the driver and / or the shaft in a rotationally fixed and axially movable manner. A ferromagnetic armature disk is arranged axially, i.e. in the axial direction, between the coil and the brake pad carrier.The armature disk is connected to the magnetic body in a rotationally fixed and axially movable manner. For this purpose, axially directed bolts are preferably connected to the magnetic body and protrude axially through the recesses in the armature disk. A braking surface is connected to or formed on the housing part or on the housing part. The brake pad carrier is arranged axially between the braking surface and the armature disk. Spring elements supported on the magnetic body press on the armature disk, in particular so that when the coil is energized, the armature disk is pulled towards the magnetic body against the spring force generated by the spring elements, allowing the brake pad carrier to run freely and, in particular, releasing the brake. When the coil is not energized, the spring elements press the armature disk away from the magnetic body towards the brake pad carrier, so that the brake pad carrier is pressed onto the braking surface and, in particular, engaging the brake.The braking surface is designed either as a finely machined surface section of the housing part, in particular the bearing flange, or as a sheet metal part that rests against the housing part, in particular the bearing flange. A bearing of the shaft, in particular the rotor shaft, is accommodated in the housing part, in particular the bearing flange. According to the invention, the current flowing through the coil or at least a measure of this current is detected, and the voltage applied to the coil is detected, or at least a measure of this voltage. Thus, the time-dependent curve of the voltage applied to the coil and the time-dependent curve of the current flowing through the coil are detected.Since, when the brake is released, the armature disk is displaced from a first axial position to a second axial position due to the reduction in magnetic force under the action of the spring force generated by the spring elements, the inductance of the coil decreases accordingly from a first value to a second value. According to the invention, the time t = 0 of brake release, i.e. the switching time, is determined from the recorded time-dependent current curve. However, no time derivative is used for this, nor is gradient formation performed; instead, a curve regression is performed. In this process, the parameters of a sectionally defined function are determined using an optimization method.In each of the sections, the function has a constant and an exponential component, with the time constant of the exponential component having different values in each section, as the time constant depends on the inductance of the coil, which is higher before the release than after. In the following, the time constant before the release is denoted by λ. ^ and then with λ ^ . So it applies If the time is the time of ventilation, the idealized current curve function is: ^ The maximum current is given by ^ ^^^ and is determined solely by the DC voltage applied to the coil and the ohmic resistance of the coil. The first section of the function begins at ^ = 0 and has the time constant ^ ^ , in particular which is determined from the quotient of the ohmic resistance and the inductance of the coil ^, in particular where ^^ = ^. At time ^ ^ the current has the value ^ ^ reached, so that the armature disk is then lifted and the brake is released, causing the current to drop almost immediately to the value ^^ ^ due to the change in inductance caused by the displacement of the armature disk, which begins the second section of the function. After that, the current increases with the other time constant ^ ^, in particular, which is determined by the quotient of the ohmic resistance of the coil and the inductance of the coil, which has now changed due to the release of the brake. It is also important to note that the ohmic resistance of the coil is temperature-dependent, and the temperature strongly depends on the operating mode. However, the inductance also exhibits a certain temperature dependence. However, since not only the temperature but also other electrically acting interference influences are present, the recorded current curve contains a noise component. Because the first section of the function This value can be inserted into the function, especially into the second part of the idealized function. Then the function I(t) has only which are then determined by an optimization procedure by minimizing the deviation from the recorded current waveform and the above function I(t) by adjusting the parameters Figure 2 shows that initial values ^ ^^^,^ , ^ ^,^ , ^ ^ ^ ,^ , ^ ^,^ , ^ ^,^ which are then continuously modified during the optimization process until the minimum deviation between the recorded current curve and the function I(t) is reached. The deviation is calculated, for example, from the sum of the squares of the differences between the respective function value and the corresponding measured value or a value extrapolated from the measured values. Thus, an optimum can be found using the method of least sum of squares and thus the values of the parameters With the parameter values determined by the optimization process, the time of ventilation is determined according to This point in time a measure of the working air gap of the armature disk, i.e. the axial length available for the movement of the armature disk between the released and applied state of the brake. This working air gap depends on the wear of the brake pads of the brake pad carrier, in particular wherein a first brake pad is arranged on the brake pad carrier on the side of the brake pad carrier facing the braking surface and a second brake pad is arranged on the brake pad carrier on the side of the brake pad carrier facing the armature disk. Preferably, the method is carried out anew each time the brake is released. The switching time, i.e. the application of the voltage to the coil, can be used as the respective time zero point. In particular, the switching time can be easily detected from the evaluation of the time-dependent voltage curve of the voltage applied to the coil and thus the respective new time zero point can be determined.Each time the procedure is carried out, the respective value of the time ^ is calculated in the manner described above. ^ Preferably, the change in this point in time ^ ^ observed and from falling below a critical value of this point in time ^ ^ whose rate of change, namely change per number of release processes associated with the change, a warning message is issued, in particular to indicate critically high wear of the brake pads. As can be seen from the section-wise definition of the idealized function I(t), the current value ^^ ^ is the first current value of the second section of the idealized function, in particular immediately at or after the time of release. Accordingly, the current value i ^the last function value of the first section of the idealized function I(t), in particular immediately before release. In further embodiments according to the invention, the simplex method of Nelder and Mead (John A. Nelder, R. Mead: A simplex method for function minimization. In: Computer Journal.7, 1965, pp. 308-313. doi:10.1093 / comjnl / 7.4.308) is used as the optimization method. In further embodiments according to the invention, the temperature of the coil is determined right at the beginning, and the starting values of the optimization method are specified based on this. The temperature is determined by determining the maximum value that occurs steadily after release, which can be determined simply by the current having a value that does not change further within the scope of the measurement accuracy.
[0003] List of reference symbols Time of ventilation λ ^ Time constant before the time of ventilation λ ^Time constant after the time of ventilation i ^ last reached current value before the time of ventilation ^^ ^ Current value immediately at or after the time of ventilation i ^^^ stationary achievable current value I(t) idealized function U(t) voltage applied to the coil
Claims
Patent claims:
1. Method for determining wear of brake pads of an electromagnetically actuated brake, wherein the brake has an energizable coil, wherein after applying a voltage to the coil, in particular for releasing the brake, the time-dependent course of the electric current flowing through the coil is recorded, characterized in that the values of parameters of a time-dependent function I(t) parameterized with the parameters are changed starting from respective initial values of the parameters until the deviation between the detected current curve and the function I(t) becomes as small as possible, in particular thus an optimum of the parameters is found, wherein the deviation is determined as a functional of the difference function between the detected current curve and the function I(t) or between a current curve extrapolated from the detected current curve and the function I(t),in particular, wherein the value of the difference function at the respective time t is formed as the difference between the function value I(t) assigned at the respective time t and the detected current value or a value extrapolated from the detected current values, wherein from the parameters thus found, in particular from the parameters of the optimum, a time, is determined as a measure of wear, in particular - wherein the measure is monitored for exceeding a predetermined threshold value - and / or wherein a warning information is issued if the measure exceeds a predetermined threshold value.
2. Method according to claim 1, characterized in that the electrical voltage applied to the coil is detected.
3. Method according to one of the preceding claims, characterized in that the functional is - the sum of absolute values of the difference assigned to a series of points in time, or - the sum of squares of the difference assigned to a series of points in time, and / or that - the deviation is formed from or by means of the sum of absolute values of differences between the function value I(t) assigned to the respective point in time t and the detected current value or a value extrapolated from the detected current values, or - the deviation is formed from or by means of the sum of squares of differences between the function value I(t) assigned to the respective point in time t and the detected current value or a value extrapolated from the detected current values. 4.Method according to one of the preceding claims, characterized in that the application of a voltage to the coil defines the time zero point, in particular t = 0.
5. Method according to one of the preceding claims, characterized in that the function I(t) is defined in sections, with a second section following a first section, with the difference between a constant, in particular i ^^^ , and the function I(t) decays exponentially, with a first time constant λ ^ is effective, whereby in the second section the difference between the constant, in particular ^ ^^^ − where the current value ^^ ^ is the current value recorded immediately at or after the time of ventilation, and the function I(t) decreases exponentially, with a second time constant λ ^is effective, wherein the first time constant is greater than the second time constant.
6. Method according to one of the preceding claims, characterized in that the function I(t) is defined section by section, namely by means of: ^ where ^ ^ the time of ventilation is, λ ^ the time constant before the time of ventilation, λ ^ the time constant after the time of ventilation, ^^ ^ the current value immediately at or after the time of ventilation and i ^^^ the stationary achievable current value, in particular and i ^ the last current value reached before the time of ventilation.
7. Method according to one of the preceding claims, characterized in that the time as a measure of wear is determined according to: where i ^the last current value reached before the time of ventilation, in particular the last value of the idealized function I(t) reached before ventilation.
8. Method according to one of the preceding claims, characterized in that the current value i that can be achieved as a steady state ^^^ The parameter acting as a brake is specified as a fixed value, i.e., is not changed.
9. Method according to one of the preceding claims, characterized in that when the brake is released, a ferromagnetic armature disk is moved toward the coil, wherein the armature disk is pressed against a brake pad prior to release, in particular by a spring element supported on a magnetic body, wherein the magnetic body receives the coil or is connected to the coil, in particular wherein the armature disk rests against the magnetic body after release.
10. Method according to one of the preceding claims, characterized in that the brake has a shaft that can be braked by the shaft and is rotatably mounted relative to a magnetic body of the brake, wherein the coil is accommodated in a recess or depression of the magnetic body, wherein a ferromagnetic armature disc is connected to the magnetic body in a rotationally fixed and axially movable manner, wherein a brake pad carrier is connected to the shaft in a rotationally fixed and axially displaceable manner, in particular by an annular driver being placed on the shaft and connected to the shaft by means of a key connection, and the driver has an external toothing that engages an internal toothing of the brake pad carrier, wherein a braking surface is arranged on the side of the brake pad carrier axially facing away from the armature disc, which braking surface is connected to the magnetic body, wherein the brake pad carrier is arranged axially between the braking surface and the armature disc,wherein the armature disc is arranged axially between the brake pad carrier and the magnetic body, wherein spring elements supported on the magnetic body press on the armature disc, in particular applying a spring force to the armature disc, in particular which is directed in the axial direction away from the magnetic body.
11. Method according to one of the preceding claims, characterized in that the change in the parameters to find the optimum is carried out by means of a simplex method, and / or that after applying a voltage, in particular a direct voltage, to the coil, the brake is released.
12. Method according to one of the preceding claims, characterized in that the time of ventilation, the time constant λ ^ before the time of ventilation, the time constant λ ^ after the time of ventilation, the last reached current value i ^before the time of ventilation, the current value ^^ ^ immediately at or after the time of ventilation and / or the stationary achievable current value i ^^^ are used.
13. Method according to one of the preceding claims, characterized in that the steady-state achievable current value i ^^^ is determined by determining, after a ventilation has been carried out, in particular first of all, the current value that is set stationary, in particular within the scope of the measurement accuracy, and then the parameters the stationary achievable current value i ^^^ not include, in particular, where the thus determined steady-state achievable current value i ^^^ , in particular taking into account the DC voltage applied to the coil, the ohmic resistance of the coil is determined, in particular and from this the temperature of the coil, and depending on this the initial values of the parameters, in particular the time constant ( λ ^ , λ ^), can be determined.
14. Electric motor with electromagnetically actuated brake and signal electronics for carrying out a method according to one of the preceding claims, characterized in that a sensor for detecting the current flowing through the coil is arranged in the electric motor and / or that a sensor for detecting the voltage applied to the coil is arranged in the electric motor, wherein the sensor or sensors are connected to signal electronics which controls and / or sets the voltage applied to the coil of the brake, in particular wherein the signal electronics has a memory for storing the time-dependent curve of the detected current and / or an evaluation unit.
15. Electric motor according to one of the preceding claims, characterized in that the brake has a shaft that can be braked by the shaft and is rotatably mounted relative to a magnetic body of the brake, wherein the coil is accommodated in a recess or depression of the magnetic body, wherein a ferromagnetic armature disk is connected to the magnetic body in a rotationally fixed and axially movable manner, wherein a brake pad carrier is connected to the shaft in a rotationally fixed and axially displaceable manner, in particular by an annular driver being placed on the shaft and connected to the shaft by means of a key connection, and the driver has an external toothing that engages an internal toothing of the brake pad carrier, wherein a braking surface is arranged on the side of the brake pad carrier axially facing away from the armature disk, which braking surface is connected to the magnetic body, wherein the brake pad carrier is arranged axially between the braking surface and the armature disk,wherein the armature disc is arranged axially between the brake pad carrier and the magnetic body, wherein spring elements supported on the magnetic body press on the armature disc, in particular applying a spring force to the armature disc, in particular which is directed in the axial direction away from the magnetic body.