DE102024204407A1 - Pulling device for electromechanical vehicle braking devices and method for operating a pulling device and electromechanical vehicle braking device - Google Patents

Abstract

The present invention provides a pulling device (10) for electromechanical vehicle braking devices (12) comprising a control unit with control program, a drive unit and a pulling element connected thereto, which is designed to manipulate brake actuators of an electromechanical vehicle braking device (12) connected to the pulling device (10), wherein the control unit with control program is designed to detect faulty release processes of the electromechanical vehicle braking device (12) and, upon detection of a faulty release process, to activate the pulling element for the purpose of manipulating the brake actuators, so that fault-free release processes can be effected in the electromechanical vehicle braking device (12).

Description

The present invention relates to a pulling device for electromechanical vehicle braking devices and a method for operating a pulling device.

State of the art

In modern vehicles with hydraulic brakes, the parking brake mechanism is implemented by a separate actuator. Electromechanical parking brakes for vehicles, particularly motor vehicles, are known from the prior art. These typically consist of a drive unit, such as an electric motor, a reduction gear, and a spreading mechanism, which also act on drum brakes. These actuators are generally designed with self-locking gear mechanisms or self-locking spreading mechanisms, ensuring that they remain securely closed even when the vehicle is parked and de-energized after activation. These actuators typically exhibit relatively low dynamics, with closing times of approximately 1.5 seconds, for example.

Electromechanically actuated service brakes are also known. These often also consist of a drive unit in the form of an electric motor, a reduction gear, and a spreading mechanism. However, such service brakes exhibit higher dynamics with closing times of approximately 150 milliseconds.

Unlike parking brake actuators, components for service brakes do not need to be self-locking. This means that in the event of a malfunction during operation, such as a power failure, the brake will release to prevent compromising the vehicle's stability. A cost-effective way to integrate a parking brake mechanism into such non-self-locking electromechanical service brakes is to use a second, usually inexpensive, actuator that can block the service brake mechanism when it is closed.

For example, a positive-locking pawl mechanism is used that can block the motor pinion or other parts of the transmission. This mechanism ensures that the service brake can be engaged in such a way that it remains engaged when the vehicle is switched off, thus enabling safe parking.

A common problem, especially with drum brakes, is the unintentional locking of the parking brake during release. Such faulty release of the parking brake can have various causes. For example, it is known that the brake shoes can actually stick to the inner wall of the drum, even though the parking actuator has already reduced the actuation force required for a proper release in the electromechanical vehicle braking system. This effect occurs particularly after extended periods of inactivity. Possible causes include chemical reactions in the friction surface, caused, for example, by corrosion. In very cold ambient temperatures, faulty release due to the brake shoes freezing to the inner walls of the drum is also known.

Although the adhesive force between the brake lining and the drum is relatively low, meaning the brake can usually be released fairly easily, this can be achieved by applying sufficient drive torque or gently tapping the drum with a hammer. However, even this low adhesive force can lead to significant braking torque. Correcting such faulty release processes due to sticking brake linings requires applying sufficient drive torque to ensure proper release. At the moment of release, there is typically a sudden torque surge at the wheel, which is both noticeable and audible. This phenomenon, also known as a release jolt, is often perceived as uncomfortable by drivers.

In the EP 3 891 410 B1 A drum brake of a motor vehicle is described.

Disclosure of the invention

The present invention provides a pulling device for electromechanical vehicle braking devices according to claim 1 and a method for operating a pulling device according to claim 9.

Preferred further training courses are the subject of the subclaims.

Advantages of the invention

The idea underlying the present invention is to provide a pulling device for electromechanical vehicle braking devices and a method for operating such a pulling device, wherein the operation of the pulling device is, firstly, aimed at the The purpose of the pulling device is twofold: firstly, to minimize adhesive effects between the brake linings and the drum, and secondly, to overcome any adhesion effects that may occur during the release of the parking brake actuation. More generally, the pulling device is intended to support the proper functioning of the components of the electromechanical vehicle braking system responsible for flawless release, thus preventing the problems described above, particularly those related to the release shock.

According to the invention, the pulling device for an electromechanical vehicle braking device comprises a pulling element designed to manipulate brake actuators of an electromechanical vehicle braking device connected to the pulling device, a control unit with a control program of the pulling device or a vehicle designed to detect faulty release processes of the electromechanical vehicle braking device and, upon detection of a faulty release process, to activate the pulling element for the purpose of manipulating the brake actuators, so that fault-free release processes can be achieved in the electromechanical vehicle braking device.

An electromechanically actuated drum brake with an operating strategy for active retraction and thus smooth brake release can be used. To release the stuck brake linings, they can be pulled on using a suitable device. The appropriate operating strategy prevents damage to the brake or actuator, or at least reduces the likelihood of such damage, while still ensuring a high probability of the linings releasing and significantly reducing the unpleasant "release shock."

It is therefore possible to overcome faulty release processes associated with insufficient functioning of the brake actuators by means of the activated pulling element. Release processes are understood here to be those functions of the electromechanical vehicle braking system that transition from a locked brake to a released brake.

An activated pulling element is understood, for example, to be an action performed by this pulling element by means of a drive unit (actuator) for the purpose of manipulation, whereby this action affects the operation of the brake actuators so that faultless release processes can be achieved in the electromechanical vehicle braking system. The manipulation encompasses any actions on the brake actuators necessary to overcome faulty release processes, particularly those related to adhesive effects occurring in the electromechanical vehicle braking system.

In this way, it is possible to reduce the probability of a release shock or the severity of such a shock. A driver of a vehicle in which the described mechanism is installed will not experience any reduction in comfort, as the assistance provided by the described pulling device in ensuring the smooth release of the electromechanical vehicle braking system is imperceptible or barely noticeable.

In other words, a control strategy for the electromechanical wheel brake actuators of a vehicle can be achieved that aims, firstly, to minimize the occurrence of adhesive effects between the lining and the drum, and secondly, to overcome any adhesion that may occur when releasing the parking brake. The control system can, for example, include the following process steps, which can be combined or executed only partially: in particular, applying the parking brake and storing relevant position and force data; furthermore, releasing the parking brake and passively resetting the service brake; furthermore, detecting stuck brake shoes via a position sensor and, if necessary, actively controlling the service brake; furthermore, actively reversing the brake actuator with variable motor current control and limitation of the pulling device to apply defined tractive forces and impulses; furthermore, additionally variable motor current control and limitation of the traction motor to apply shear stress to assist in releasing the brake shoes.

The proposed strategy for loosening the brake pads offers the following advantages in particular: it reduces the probability and severity of the release shock; it prevents mechanical damage to the components via software; it results in no/minimal loss of comfort for the driver (control is imperceptible/barely noticeable); and it can prevent wheel locking with a high probability, which can be particularly relevant when the coefficient of friction between the tire and road surface is low.

According to a preferred embodiment of the pulling device, the control unit with control program is designed to detect faulty release processes by evaluating a force To detect the path diagram of the brake actuators.

It is conceivable that the control unit with control program receives the necessary information for a corresponding evaluation from the electromechanical vehicle braking device and a sensor suitable for this purpose.

It is known that, for example, measured actuation forces at the brake actuators are used to control electromechanical vehicle braking systems. An estimation of the respective actuation force via motor current and position can also be used. In the case of faulty release processes after parking, related to adhesive effects, also known as brake shoe sticking, the curves in the force-displacement diagram of the brake actuators change. Even before reaching the actual operating range, deviations from standard curves can be observed in the brake shoe sticking range. The pulling device according to the invention utilizes these circumstances during an evaluation, for example, by comparing the current actual curve with standard curves, so that a malfunctioning release process can be detected at an early stage.
It is also conceivable that the control unit and its control program are designed to obtain the necessary information directly from the electromechanical vehicle braking system, for example, using suitable sensors. This evaluation could include a comparison with standard values stored in the control program or, more generally, a real-time evaluation of the brake actuators during a release process.

According to a preferred embodiment of the pulling device, the control unit with control program is designed to detect faulty release processes by evaluating a current profile of a respective drive unit of the brake actuators.

In this case, the towing device is appropriately coupled to the electromechanical vehicle braking system so that this information can be acquired by the control unit with its control program. Detection processes are thus particularly simple and reliable.

According to a preferred embodiment of the pulling device, the control unit with control program is designed to detect faulty release processes by evaluating motor rotation processes of a respective drive unit of the brake actuators.

During faulty release processes, the motor rotations of the respective drive unit of the brake actuators differ from their behavior during faultless release processes. This fact can be advantageously used here for the safe and reliable detection of a faulty release process. When the electromechanical vehicle braking device is activated, relevant information from the brake actuators can be stored, which can then be used for this embodiment. For example, the position at which the parking brake level is reached, relative to an absolute zero position of the brake actuator, is stored. In this context, the corresponding motor revolutions from the zero position to the parking position can also be determined. During release, deviations from the zero position can occur due to friction in the brake actuator and hysteresis effects in the friction point between the brake pad and its corresponding counterpart. This can be an initial indication of brake pad sticking, so the pulling device according to the invention can activate subsequent pulling processes to support the release process by appropriately evaluating the motor rotations.

According to a preferred embodiment of the pulling device, the control unit with control program is designed to send control commands to a vehicle with an electromechanical vehicle braking device for the purpose of rotating at least one wheel of the vehicle on which the electromechanical vehicle braking device is arranged, so that the pulling element can be supported in effecting error-free release processes of the electromechanical vehicle braking device.

The rotation of the corresponding wheel can generate shear stresses on the bonded joints of the electromechanical vehicle braking system, thus providing additional support to the activated pulling element. Faulty release processes due to adhesive effects can therefore be overcome even more effectively and precisely. The combination of the release effect via the activated pulling element and the effect of the rotation results in a particularly effective transformation of the faulty release process into a fault-free release process.

According to a preferred embodiment of the drawing device, the drawing element is activated by means of a defined maximum current. an actuator of the pulling element, wherein the defined maximum current can be controlled by the control device with control program depending on the detected faulty release process.

In other words, depending on the detected faulty release process, the defined maximum current can be controlled to prevent damage to the brake and/or brake actuators. For this purpose, the defined maximum current can be limited by the control unit and its control program. This limitation can be based, for example, on the strength of the bond between the brake pad and its corresponding counterpart. For the actuator, the strength of the retracting force elements of the pulling device, an axial bearing, and any asymmetrical gear components can also be considered, as these can limit the retraction force compared to the maximum actuation force.

According to a preferred embodiment of the pulling device, the defined maximum current can be determined by the control unit with control program depending on the current position of the respective brake actuator.

In this way it is possible to effect a release process sufficient for the respective purposes, whereby mechanical damage can be avoided due to consideration of the current position of the respective brake actuator.

According to a preferred embodiment of the drawing device, the defined maximum current is not constant, which may be a maximum achievable threshold value (capping) for the fluctuating or pulsed current supply.

In this way, for example, impulsive force peaks or vibrations can be generated, so that detected faulty dissolving processes can be converted into fault-free dissolving processes.

Furthermore, according to the invention, an electromechanical vehicle braking device with a pulling device according to one of claims 1 to 8 is presented.

The aforementioned advantages apply equally to the presented electromechanical vehicle braking device with the pulling device according to the invention.

According to the invention, in the method for operating a pulling device according to the invention, the pulling device detects whether a faulty release process is occurring in an electromechanical vehicle braking device coupled to the pulling device; depending on the detected faulty release process, the pulling device is activated so that the detected faulty release process is converted into a fault-free release process in the electromechanical vehicle braking device.

The detection of a faulty release process can be achieved via the motor current and the position of the components or other proportional data (FS characteristic curve). Detection can be performed by the control unit of the pulling device, which can either acquire the relevant data itself or obtain it from other sensors, other vehicle control units, or other data sources/measurements.

According to a preferred embodiment of the method, at least one control command is sent by means of the pulling device to a vehicle with an electromechanical vehicle braking system for the purpose of rotating at least one wheel of the vehicle on which the (fixed) electromechanical vehicle braking system is arranged, so that a pulling element of the pulling device can be supported in effecting faultless release processes of the electromechanical vehicle braking system. The rotation of the corresponding wheel can cause corresponding shear loads on the adhesive bonds of the electromechanical vehicle braking system, so that the activated pulling element can be additionally supported in this way. Faulty release processes due to adhesive effects can thus be overcome even better and more precisely. The combination of the release effect by means of the activated pulling element and the effect of the rotation together lead to a particularly effective conversion of the faulty release process to a faultless release process.

According to a further preferred embodiment of the method, the at least one control command is designed to generate a rising or impulsive drive torque at the at least one wheel for the purpose of rotation. Depending on the application scenario, this allows for particularly sensitive support of the towing device. In particular, excessive vehicle acceleration can be prevented, for example, by means of a rapid torque build-up. Unintentional lurching of the vehicle when the stuck brake is released abruptly can also be reliably prevented. While, similar to the prior art, a A breakthrough occurs, but it is significantly weaker because the presented method allows for a particularly defined procedure.

According to a further preferred embodiment of the method, the at least one control command is designed to adjust the rotation of the at least one wheel depending on a vehicle movement detected by the pulling device and is also designed to effect acceleration or braking operations on the vehicle, so that large vehicle movements or wheel spin can be avoided. The pulling device can, for example, be connected to a speed sensor device or the like of the vehicle and thus perform detection operations using information read from or transmitted by the speed sensor device. In other words, information about vehicle movements can be used by the pulling device so that corresponding adjustment operations can be carried out. Finely tuned release operations can thus be performed without causing any jerky movements of the vehicle that would disturb the driver.

According to a further preferred embodiment of the method, the at least one control command is designed to effect respective drive torques or braking operations at at least two wheels, thus enabling a particularly defined support of the pulling element of the pulling device in effecting faultless release processes of the electromechanical vehicle braking device. In this way, a particularly defined release process can also be effected while the vehicle is stationary. It can therefore be achieved, for example, that the release process is supported at one wheel, while braking continues at another wheel.

As a first step, for example, to engage the parking brake, the service brake can be set to a desired torque and locked by the parking actuator. The system then records the position at which the parking brake level was reached, relative to the actuator's absolute zero position (e.g., how many engine revolutions were made from the zero position to the parking position). In a further step, for example, when the parking brake actuator is released, it can optionally be pushed back if it is not actively energized (depending on the sufficiency of the force applied, a reset may or may not occur). The actuator's position and force change from the nominal force level or position when parked to the force/position in the de-energized state. Due to friction within the actuator and hysteresis effects at the friction point between the lining and the drum, the achieved position typically deviates from the absolute zero position. This results in residual force, and the motor's rotor position sensor can detect a position that deviates from the zero position (the motor is pushed back fewer revolutions than were required to travel from the absolute zero position to the park position). In a further step, if the jaws stick to the drum, the position achieved in the previous step can change. This position may lie, for example, in the transition region of the Fs characteristic curve, which is altered by sticking and tension between the drum and lining. This can lead to the detection of a deviating position (force, if a force sensor is present). This can provide an initial indication of jaw sticking. Subsequently, the actuator can be actively reversed using a small reversing current (irev). If the jaws are not stuck, this will achieve the absolute zero position. However, if the jaws are stuck, the achieved position will deviate because the pulling mechanism can engage, preventing the jaws from reversing. Furthermore, during reversing, changes in the force-displacement characteristic can be detected indirectly, for example, through changes in the current-position characteristic of the motor, or directly based on the measured force. This allows for the detection of brake shoe sticking. In a further step, if brake shoe sticking is detected, a defined maximum current, irev max, can be set for reversing (this current can represent a cap on the utilized current value, although the actual current used may be below this cap). This current is limited to prevent mechanical damage to either the brake or the actuator. For the brake, the strength of the bond between the lining and the backing plate is particularly important. For the actuator, the strength of the retracting force elements (pulling device, thrust bearings, and any asymmetrical gear components) must be considered, as these can limit the retraction force compared to the maximum actuation force. Additionally, irev max can be made dependent on the actuator's position. If the current is close to zero, for example with new brake pads, it can be reduced. This is necessary because, in this case, a sudden release of the stuck pads could cause the actuator to travel at high speed against its rear end stop and damage it.

Optionally, a non-constant current can also be set in this step. This allows, for example, impulsive power peaks ("virtual"). Hammer blows or vibrations can be generated, which can loosen the bond between the lining and the drum. It can be detected whether the maximum reversing current (irev max) is sufficient to loosen the bonded jaws, as the actuator's position may vary. In a further step, for example, an externally applied drive torque can induce shear stress in the bond between the jaws and the actuator. This drive torque can then be transmitted directly to the drum via the drive mechanism in the case of driven wheels, or indirectly via the tire-road contact in the case of non-driven wheels. If loosening by the reversing current as described in the previous step is not possible, the combination of pulling and additional shear stress from a drive torque increasing against a limit can be used to loosen the bond between the jaws and the actuator.

This can cause a release jolt, but it is significantly weaker because the required drive torque is considerably lower due to the additional pulling force. To prevent or reduce vehicle lurching when the stuck brake is released abruptly, the drive torque can be applied gradually or in pulses. The resulting rapid torque reduction prevents excessive vehicle acceleration. If movement is detected by the speed sensors, the vehicle can be actively braked using the electric motor and wheel brakes, preventing significant vehicle movement or wheel spin. For driven axles, it is optionally possible to perform the release strategy on individual wheels while the other wheels are braked. This allows for release even when the vehicle is stationary.

The drawing device can also be characterized by the features and advantages mentioned in connection with the method, and vice versa. Further features and advantages of embodiments of the invention will become apparent from the following description with reference to the accompanying drawings.

Brief description of the drawings

The present invention will be explained in more detail below with reference to the exemplary embodiments shown in the schematic figures of the drawing.

• 1 eine schematische Darstellung der Ziehvorrichtung an einer elektromechanischen Fahrzeugbremsvorrichtung;
• 2 eine elektromechanische Fahrzeugbremsvorrichtung mit einer Ziehvorrichtung nach einem der Ansprüche 1 bis 8;
• 3 eineeine Kraft-Weg-(Fs-) Kennlinie für Trommelbremse; und
• 4 eine Blockdarstellung von Verfahrensschritten des Verfahrens zum Betreiben einer Ziehvorrichtung.

They show:

• 1 a schematic representation of the pulling device on an electromechanical vehicle braking device;
• 2 an electromechanical vehicle braking device with a pulling device according to one of claims 1 to 8;
• 3 a force-displacement (Fs) characteristic curve for drum brakes; and
• 4 A block diagram of the process steps of the procedure for operating a drawing device.

In the figures, identical reference symbols denote identical or functionally equivalent elements.

1 Figure 1 shows a schematic representation of the pulling device 10 on an electromechanical vehicle brake device 12. In this embodiment, the electromechanical vehicle brake device 12 is designed as a drum brake device. This embodiment is shown without a drum. The pulling device 10 is shown arranged on a spreading unit 14. The spreading unit 14 presses the brake linings 16, which are located on respective brake carriers (brake shoes or brake shoes) 18, against the drum with a defined clamping force.

In this state, the spreading unit 14 is moved by one or more brake actuators (not shown), which are held in this position by a locking element (also not shown) so that they cannot be pushed back. However, it is conceivable that a self-locking system could alternatively be provided. In a fault-free release process, the operation of the unlocked brake actuators is sufficient to release the brake linings 16 from the inner wall 20 (of the drum of the drum brake) of the electromechanical vehicle brake device 12, so that the electromechanical vehicle brake device 12 is now in an open state. For this purpose, for example, the restoring forces of the return springs 22 (shown) may be sufficient, or additional active actuation of the brake actuators may be considered sufficient.

If, however, the pulling device 10 or the vehicle detects a faulty release process, for example due to the brake pads sticking to the inner wall 20 of the electromechanical vehicle braking device 12, for example due to adhesive effects in connection with corrosion or a particularly low outside temperature, the normal active reversing processes of the brake actuators may not be sufficient to end the parking process.

In this case, the presented pulling device 10 is intended to provide the necessary support so that error-free release processes can be achieved in the electromechanical vehicle braking device 12. A control unit with a control program (not shown in detail) is designed not only to detect faulty release processes of the electromechanical vehicle braking device 12, but subsequently to activate a pulling element of the pulling device 10 (also not shown in detail) for the purpose of manipulating the brake actuators, so that error-free release processes can be achieved in the electromechanical vehicle braking device 12.

2 shows an electromechanical vehicle braking device 12 with a pulling device 10 according to one of claims 1 to 8.
The electromechanical vehicle braking device 12 can, for example, be designed as a drum brake device or as a service brake device with additional brake actuators.

3 shows a force-displacement (Fs) characteristic curve for drum brakes.

In 3 An example of a force-displacement (Fs) characteristic curve for drum brakes is shown. The Fs characteristic curve can include a clearance range in which only the force of the return spring is overcome, a transition range in which the shoes contact the drum, and a working range in which the shoes are fully in contact with the drum.

Hysteresis behavior can be detected.
The applied current may be sufficient to release the brake in one case (Case 1) and not in another (Case 2). This is evident from the fact that in Case 2, the zero position of the actuator deflection (X-axis) is not reached.

For controlling the drum brake actuator, for example, a measured actuation force or an estimation of the actuation force via motor current and position can be used. When the brake shoes stick after parking, the behavior changes as described in... 3 The characteristic curves are used to apply the inventive operating strategy for releasing the brake. The force curve FA shown is an example of an embodiment with a large clearance between the push and pull transmission device. Depending on the clearance implemented, the curve changes below the point "force level/position without current (in the transition region)" with respect to the actuator travel required to reach a force level. At the point force level/position without current, the brake is unlocked but not retracted. From point P0 (no force via the pull device but a deflection remains), a force in the negative direction (reversing) can be achieved with a specific current. In one instance, the current is sufficient to release the brake and reverse it (to point P1), and in another, a force in the negative direction occurs, but the brake cannot be reversed all the way back to its starting position (point P2), or a corresponding clearance exists.

4 shows a block diagram of process steps of the method for operating a drawing device 10 according to an embodiment of the present invention.
In the method for operating a drive control device according to the invention, a detection S1 is carried out by means of a pulling device 10 according to one of claims 1 to 8 as to whether a faulty release process is present on an electromechanical vehicle brake device 12 coupled to the pulling device 10; this is followed by an activation S2 of the pulling device 10 depending on the detected faulty release process, so that the detected faulty release process is converted to a fault-free release process in the electromechanical vehicle brake device 12.

Although the present invention has been fully described above with reference to the preferred embodiment, it is not limited to this embodiment but can be modified in many different ways.

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions.

Cited patent literature

• EP 3 891 410 B1 [0008]

Claims (14)

Pulling device (10) for an electromechanical vehicle braking device (12) comprising: - a pulling element designed to manipulate brake actuators of an electromechanical vehicle braking device (12) connected to the pulling device (10), - a control unit with a control program of the pulling device (10) or of a vehicle designed to detect faulty release processes of the electromechanical vehicle braking device (12) and, upon detection of a faulty release process, to activate the pulling element for the purpose of manipulating the brake actuators, so that fault-free release processes can be effected in the electromechanical vehicle braking device (12). Pulling device (10) after Claim 1 , wherein the control unit with control program is designed to detect faulty release processes by evaluating a force-displacement diagram of the brake actuators. Pulling device (10) according to one of the Claims 1 or 2 , wherein the control unit with control program is designed to detect faulty release processes by evaluating a current profile of a respective drive unit of the brake actuators. Pulling device (10) according to one of the preceding claims, wherein the control device is designed with control program to detect faulty release processes by means of an evaluation of motor rotation processes of a respective drive unit of the brake actuators. Pulling device (10) according to one of the preceding claims, wherein the control unit is designed with a control program to send control commands to a vehicle with an electromechanical vehicle brake device (12) for the purpose of rotating at least one wheel of the vehicle on which the electromechanical vehicle brake device (12) is arranged, so that the pulling element can be supported in effecting error-free release processes of the electromechanical vehicle brake device (12). Pulling device (10) according to one of the preceding claims, wherein the activation of the pulling element can be effected by means of a defined maximum current at an actuator of the pulling element, wherein the defined maximum current can be controlled by the control device with control program depending on the detected faulty release process. Pulling device (10) after Claim 6 , wherein the defined maximum current can be determined by the control unit with control program depending on the current position of the respective brake actuator. Pulling device (10) according to one of the Claims 6 or 7 , where the defined maximum current is not constant. Method for operating a drawing device (10) according to one of the Claims 1 until 8 , comprising the steps: - Detecting (S1) using a pulling device (10) after one of the Claims 1 until 8 , whether a faulty release process is occurring at an electromechanical vehicle brake device (12) coupled to the pulling device (10); - Activation (S2) of the pulling device (10) depending on the detected faulty release process, so that the detected faulty release process is converted to a fault-free release process at the electromechanical vehicle brake device (12). Method for operating a drawing device (10) according to Claim 9 , comprising the further step: - Sending at least one control command by means of the pulling device (10) to a vehicle with electromechanical vehicle braking device (12) for the purpose of rotating at least one wheel of the vehicle on which the electromechanical vehicle braking device (12) is arranged, so that a pulling element of the pulling device (10) can be supported in effecting error-free release processes of the electromechanical vehicle braking device (12). Method for operating a drawing device (10) according to Claim 10 , wherein the at least one control command is designed to produce a swelling or impulse-like driving torque on the at least one wheel for the purpose of rotation. Method for operating a drawing device (10) according to Claim 10 or Claim 11 , wherein the at least one control command is designed to adjust the rotation on the at least one wheel depending on a vehicle movement detected by means of the pulling device (10) and is also designed to effect acceleration or braking operations on the vehicle so that large vehicle movements or wheel spin can be avoided. Method for operating a drawing device (10) according to one of the Claims 10 until 12 , whereby at least one control command is interpreted is to effect respective drive torques or braking operations at at least two wheels, so that a particularly defined support of the pulling element of the pulling device (10) is possible in effecting error-free release operations of the electromechanical vehicle braking device (12). Electromechanical vehicle braking device (12) with a pulling device (10) according to one of the Claims 1 until 8 .