Method for operating electromechanical brake device and electromechanical brake device for motor vehicle

Abstract

The invention relates to a method for operating an electromechanical brake device (1) comprising a brake part (32), a counter brake part (2) and an electric actuating device (5), in which method the brake part (32), the counter brake part (2) and the electric actuating device (5) are actuated in order to generate a braking action. The braking part (32) is moved in the adjustment direction by means of an actuating device (5) from a release position, in which an air gap (L) is positioned between the braking part (32) and the counter braking part (2), against the air gap (L) to a braking contact (K) with the counter braking part (2). In order to achieve improved operation, according to the invention, before the braking action is generated, the braking part (32) is positioned by the actuating device (5) in an initial position (IN) in which a defined air gap width (B) of the air gap (L) between the braking part (32) and the counter braking part (2) is predefined.

Description

Prior art

[0001] The present invention relates to a method for operating an electromechanical braking device, which comprises a braking part, a counter-braking part and an electric actuator. In this electromechanical braking device, in order to generate a braking application, the braking part is moved by the actuator in an adjusting direction from a release position in which an air gap is arranged between the braking part and the counter-braking part, and at the same time, it moves against the air gap to the braking contact with the counter-braking part. The electromechanical braking device is also the subject matter of the present invention.

[0002] Such a braking device of a motor vehicle is in the form of a friction brake, in which the braking part supported on the chassis and fixed relative to the rotation of the wheel to be braked can be brought into braking application together with the counter-braking part rotating with the wheel by means of an actuator. When in braking application, a friction contact, i.e., a so-called braking contact, is generated between the braking part and the counter-braking part, and the braking torque generated by friction increases with the increase of the adjusting force applied by the actuator in the adjusting direction.

[0003] A common design is a disc brake, which is known in principle. In the disc brake, the counter-braking part is formed by a brake disc rotating with the wheel, and the brake disc is axially surrounded by a brake caliper on both sides. By means of at least one preferably linear actuator drive axially supported on the caliper, the braking part, usually a brake lining, can be adjusted in the axial adjusting direction and thus frictionally contacted with the axial side of the brake disc. When braking is applied, the brake disc is frictionally clamped between the adjusted braking part and another braking part axially supported on the brake caliper.

[0004] A prerequisite for the proper function and precise response of the brake is that when no braking is applied, a distance, i.e., a so-called air gap, is provided between the braking part and the counter-braking part in the adjusting direction. When braking is applied, the braking part moves perpendicular to the air gap towards the counter-braking part by the actuator until the air gap is overcome and a friction braking contact is reached, so that a braking application is generated.

[0005] For a reproducible response of the brake during actuation, it is important that, in the unapplied state, the air gap in the axial adjustment direction has an as-constant-as-possible air gap width. For example, due to wear of the brake lining and / or the brake disc, this air gap width may increase during operation and must be readjusted accordingly. It is known from DE 10 2017 123 266 A1 that the actuator includes at least one actuator drive that can be driven by an electric actuator, such as a spindle drive, etc. Thereby, the brake part can advance in the adjustment direction towards the counter-brake part to reduce the width of the air gap and generate a brake application, or conversely, the brake part can be set backwards away from the counter-brake part to increase the width of the air gap and release the brake. Although the air gap width can be changed by the actuator, this does not result in a more reproducible response during actuation. This also results in an annoying noise during driving.

[0006] In view of the problems described above, one object of the present invention is to achieve improved operation in the case of an electro-mechanical brake device. Summary of the Invention

[0007] According to the present invention, this object is achieved by a method having the features of claim 1 and a brake device as claimed in claim 11. Advantageous refinements result from the dependent claims.

[0008] A method for operating an electro-mechanical brake device is provided, which electro-mechanical brake device includes a brake part, a counter-brake part, and an electric actuator. In this method, in order to generate a brake application, the brake part is moved by means of the actuator in the adjustment direction from a release position in which there is an air gap between the brake part and the counter-brake part, and at the same time, it moves against the air gap to a braking contact with the counter-brake part. According to the present invention, it is provided that, before generating a brake application, the brake part is positioned by the actuator in an initial position in which a defined air gap width of the air gap between the brake part and the counter-brake part is specified.

[0009] According to the method according to the invention, the braking device is initialized by means of an actuator, wherein the braking part is positioned relative to the counter-braking part in a defined manner. This is achieved by adjusting the braking part to an initial position. A defined air gap width preset to a predetermined value corresponds to the distance between the friction surfaces facing each other in the axial direction of the braking part and the counter-braking part in the adjustment direction. Thus, the adjustment distance between the initial position and the braking contact required for the braking process that must be overcome by operating the actuator can be kept constant during driving. Changes in the width of the air gap occurring during operation, for example due to wear, abrasion, temperature fluctuations, etc., can be compensated during the operation of the vehicle by the method according to the invention, so that a consistent and reproducible response of the brake can be achieved in an advantageous manner.

[0010] In the prior art, the air gap is usually adjusted during the installation or maintenance of the braking device, wherein, despite relatively great effort, the changes in the air gap width occurring during driving cannot be satisfactorily compensated due to continuous wear and abrasion. In contrast, the advantage of the present invention is that an electric actuator can be used to achieve optimal functional reliability during the operation of the vehicle without external maintenance or adjustment effort, and a consistently high level of operating comfort can be achieved only by the actuator integrated in the brake.

[0011] The initialization of the braking device according to the invention can be carried out by controlling the actuator, for example automatically by means of an electronic control system available in the vehicle. For example, when the vehicle is started, the braking part can be adjusted to the initial position in the usual way, so that not only wear can be compensated, but also potential effects caused by changing environmental conditions, such as extreme temperature changes, etc., can be compensated. Alternatively or additionally, the initial position can be set after the braking process or each braking process, so that optimal operating conditions can be ensured for subsequent braking operations.

[0012] The defined air gap width, which can also be referred to as the initial width, is greater than zero. During the braking contact, which can also be referred to as the application position or brake application, there is no air gap, i.e., the air gap width is zero. The defined air gap width is preferably less than the maximum air gap width that can be specified by the actuator between the braking part and the counter-braking part.

[0013] According to the invention, the initial position set by the actuator forms the starting or initial position of the braking or working stroke also generated by the actuator, by means of which the braking part is adjusted in the adjustment direction during the braking operation until the frictional braking contact with the counter-braking part. Thus, the braking part preferably remains at rest in the initial position at least temporarily, or is fixed in a releasable manner before the start of a subsequent braking process. Then, the braking part is moved from the initial position to the braking contact by means of the braking stroke. Thus, the following advantage is achieved: the braking stroke must consistently correspond to a defined air gap width during each braking operation. A significant advantage resulting from this is that the response remains constant regardless of wear.

[0014] Another advantage is that, according to the invention, the adjustment characteristics of the actuator can be optimally adapted to the constant adjustment distance of each braking process. For example, an optimized force-displacement characteristic adapted to the air gap width can be specified. For example, starting from the initial position, the braking part can first be moved quickly with a low force, and optionally a higher force can be applied at a lower adjustment speed when reaching the braking contact or shortly before reaching the braking contact. This can be carried out, for example, by means of a corresponding electrical control of a servo motor. Alternatively or additionally, a non-linear mechanical adjustment kinematics of the actuator can be provided, for example, by means of known wedge disks, spherical ramps or inclined pin devices, etc. This allows for optimized response and avoids unwanted noise generation.

[0015] Another advantage is that the specification of a defined air gap width allows for the adjustment of the braking characteristics and the response of the brake without additional installation or adjustment effort. For example, a targeted reduction of the defined air gap width can achieve a faster and more sensitive response of the brake, for example, for a sporty driving style.

[0016] An advantageous execution of the method can include performing a calibration routine to set the defined air gap width, including the following steps:

[0017] - Adjusting the braking part to a reference position,

[0018] - Adjusting the braking part from the reference position to the initial position.

[0019] Preferably, the reference position is formed by the braking contact.

[0020] The calibration routine is a calibration method for determining the defined air gap width by means of an adjustment drive. The reference position is a position significantly related to the braking contact, such as the position of the braking contact on the adjustment direction itself. Possible reference positions have a fixed specified distance to the braking contact and are therefore synonymously referred to as the braking contact hereinafter.

[0021] In a first step, the braking part is adjusted by the actuator towards the counter-braking part, forward adjustment by definition, until the braking part contacts the counter-braking part at the braking contact. This adjustment can also be referred to as advancement, corresponding to the forward adjustment direction. The reference position in the braking contact can preferably be set to the zero position. The braking part is adjusted away from the counter-braking part from the braking contact in the reverse adjustment direction and is adjusted back to the initial position by an adjustment distance corresponding to the defined air gap width. This adjustment can also be called reset according to the backward adjustment direction. This enables precise positioning of the braking part in the initial position with little effort by simply specifying the adjustment distance, regardless of the possible offset of the absolute position of the braking contact due to wear, etc.

[0022] The calibration routine can be executed when starting the vehicle before the start of the travel, preferably automatically. Alternatively or additionally, it can be envisaged and can be executed after one or each braking operation, based on the braking contact that inevitably occurs during the process.

[0023] To implement the foregoing procedure, the reference position at the braking contact can be recorded with little effort and then the actuator can be controlled so as to adjust the braking part from the reference position by a specified adjustment distance to the initial position. For example, in the braking contact, the current zero position can be electronically recorded and stored. Based on this, the actuator can be controlled to adjust the size of the defined air gap width so as to set the initial position.

[0024] Advantageously, the current position of the braking part is preferably detected by a sensor device. Preferably, the braking contact can be detected by an electrical sensor device, set to the zero position and stored in the electronic control device. The sensor device can preferably be arranged on the actuator or formed together with the actuator. For example, a force sensor records that the braking part stops at the braking contact with the counter-braking part. With particularly little effort, the stop at the braking contact can be detected by an increase in the current generated by the electric servo motor. Alternatively or additionally, a measuring device can also be provided, which is designed to measure the absolute or relative position value of the braking part relative to the counter-braking part, for example by means of known distance or position measuring methods.

[0025] In an advantageous design, the sensor device can be in the form of a rotor position sensor of the actuator motor. For example, an actuator motor in the form of a synchronous motor is usually already equipped with a rotor position sensor. Due to the previously known mechanical ratio between the rotation angle of the rotor shaft and the stroke of the thrust piece, the absolute position value can be determined by determining the rotation angle of the rotor shaft.

[0026] Preferably, the rotor position sensor can be in the form of an inductive sensor, a magnetic sensor or an optical sensor.

[0027] The actuator can be position-controlled. For example, a position sensor can be provided which indicates the absolute or relative position value of the braking part relative to the counter-braking part. Based on the detected zero position at the braking contact, the value of the initial position with the defined specified air gap width can be determined, which is used to control the actuator.

[0028] It can be advantageous if the actuator is distance-controlled. This enables the actuator to be adjusted to the initial position with little effort at an adjustment distance specified by the control system. For example, such distance control can be achieved with little effort by an electric motor control system which controls a servo motor using a signal sequence that generates an adjustment at the defined specified adjustment distance.

[0029] An advantageous implementation is made possible by the fact that the actuator has an actuator drive and a spindle drive which can be rotationally driven by a servo motor. The spindle drive forms a linear drive for the continuous operation of the braking part, which has a threaded spindle engaged in a spindle nut in a known manner, and the spindle nut can be rotationally driven relative to the threaded spindle by an actuator motor. The adjustment distance is directly related to the amount of rotation of the rotor shaft of the servo motor and the pitch of the threaded spindle. Thus, a defined rotation angle of the rotor shaft can be specified by controlling the servo motor with a control signal, and controlling the servo motor with the control signal causes the braking part to be linearly adjusted at the defined adjustment distance. For example, at the braking contact, the servo motor can be controlled with a defined electrical control signal in order to move the braking part to the initial position by distance control. An advantage of this is that the method according to the invention can be implemented solely by the electrical control of the servo motor, including the detection of the braking contact by evaluating the motor current and the position-accurate adjustment of the initial position.

[0030] If required, additional position sensors, displacement sensors, force sensors or other sensors can be provided, for example to redundantly detect the braking contact or monitor the defined air gap width.

[0031] Preferably, the actuator has a first actuator driver and a second actuator driver connected in series with the first actuator driver. In each case, the actuator driver forms an axially effective lifting or adjusting device in the adjusting direction. For example, the actuator driver can have a spindle drive. Other designs of the actuator driver can also be used, and these other designs of the actuator driver can include, for example, bevel bearings, cam plates or cam disks, tilt pin assemblies, etc., and also convert the rotation of the drive element into a linear adjustment of the output element. Since the two actuator drivers are arranged in series in the adjusting direction, that is, arranged one behind the other, the braking element can be linearly adjusted together with the second actuator driver by actuating the first actuator driver to generate a braking application. By adjusting the second actuator driver independently of the actuation of the first actuator driver, the air gap defined according to the present invention can be adjusted. Therefore, the first actuator driver can be continuously operated within the optimal operating range.

[0032] In the foregoing design, it is advantageous that the braking application is generated by the first actuator driver, and the first actuator driver can thus be described as a braking driver or a working driver, and the initial position is set by the second actuator driver by means of an actuator driver that can be correspondingly described as an adjusting driver. During operation, when braking is applied, the braking driver preferably performs a constant braking stroke during each braking operation, which moves the braking part forward to apply the brake. By means of an adjusting driver preferably having a spindle drive, the braking part can be adjusted to the initial position. The fact that the defined air gap width is adapted to the fixed, constant braking stroke of the braking driver means that the braking driver can be continuously operated at the optimal operating point.

[0033] In the case where the adjusting device has two actuator drivers arranged in series, among the actuator drivers, the first actuator driver, the braking driver, performs a constant braking stroke, and the second actuator driver, the adjusting driver, is adjustable for adjusting the air gap. The method according to the present invention can include the following steps:

[0034] - Reset the adjusting driver,

[0035] - Move the braking driver forward,

[0036] - Move the alignment drive device forward to the braking contact,

[0037] - Reset the braking driver.

[0038] Moving the braking driver forward means adjusting in the adjusting direction towards the reverse braking part, an adjustment that is forward by definition. Therefore, resetting means adjusting away from the reverse braking part in the opposite adjusting direction, an adjustment that is backward by definition, i.e., backward.

[0039] After performing the aforementioned steps, the brake part is positioned in the initial position. This achieves the following advantages: during a subsequent braking process in which the brake part moves forward towards the counter brake part with a constant braking stroke, the brake part is adjusted to the optimal application of braking.

[0040] In the case of an electromechanical brake device for a motor vehicle, the electromechanical brake device includes an actuator and a brake part connected to the actuator, the brake part being adjustable by the actuator in an adjustment direction and being able to enter into a braking application together with a counter brake part, and the electromechanical brake device includes control means for controlling the actuator. According to the invention, it is provided that, for the purpose of setting the initial position, the actuator can be controlled by the control means, and in the initial position, a defined air gap width of the air gap between the brake part and the counter brake part is specified.

[0041] The features mentioned above in connection with the method according to the invention can be implemented individually and in combination in a brake device according to the invention.

[0042] The adjustment direction preferably extends along an axis, for example the axis of a spindle drive of the actuator drive.

[0043] Advantageously, the control means is connected to at least one sensor device, the at least one sensor device being designed to detect the position of the actuator and / or to detect the adjustment distance of the actuator. An advantageous design is that the control means is connected to at least one sensor device, the at least one sensor device being designed to detect the braking contact between the brake part and the counter brake part. As explained above in connection with the method according to the invention, for example, it is advantageous to detect the braking contact as a zero position, for example by monitoring the motor current of a servo motor or by another measuring method. The measured values recorded in this way can be stored and processed in a control unit in order to control the actuator motor of the adjustment device on this basis.

[0044] Preferably, the control means is designed to adjust the actuator to a predetermined position and / or to adjust the actuator by a predetermined adjustment distance. This allows, for example, the initial position to be set based on the braking contact.

[0045] It can preferably be provided that the control means has a control input for inputting an initial value, and the control means is designed to set the actuator device to an initial position corresponding to the input initial value. This allows the initial position to be adjusted to achieve a desired braking characteristic. For example, in order to achieve a faster response and / or a better braking effect of the braking, the defined air gap width can be reduced.

[0046] Preferably, the adjustment drive for adjusting the air gap width, which can also be referred to as an adjustment drive device, can have a spindle drive. Another adjustment drive, which can also be referred to as a brake drive or a working drive, can have, for example, an inclined plane bearing, a cam plate or a cam disk, an inclined pin arrangement, etc. These drive devices are preferably designed such that they perform a constant braking stroke, i.e., a constant adjustment distance in the adjustment direction, each time the brake is applied.

[0047] It can be provided that the braking device includes an actuator and a braking part connected to the actuator, the braking part can be adjusted by the actuator along an axis, i.e., in the adjustment direction, and can enter into a braking application together with a counter-braking part, wherein the actuator has a first actuator drive and a second actuator drive connected in series with the first actuator drive, wherein the first actuator drive has a rotatably driven first drive wheel, and the second actuator has a rotatably driven second drive wheel coaxial with the first drive wheel, and a coupling device is arranged between the first drive wheel and the second drive wheel. It can be provided that the coupling device is in the form of a friction coupling with a friction element, and the friction element is frictionally connected to a counter-friction element when the coupling engages.

[0048] Hereinafter, the first drive wheel and the second drive wheel are also collectively referred to as two drive wheels or simply as drive wheels.

[0049] The drive wheels can be in the form of gears, such as spur gears, or in the form of belt wheels or toothed belt wheels or worm wheels, such that generally gears are provided by means of which the drive torque can be coupled from an electric servo motor into the actuator drive.

[0050] A friction coupling can be realized between the drive wheels. The friction coupling includes a friction element torque-locked to one of the drive wheels and a corresponding counter-friction element torque-locked to the other drive wheel. The friction element can be frictionally coupled to the counter-friction element in any relative angular position. Compared with the form-fitting snap connection in the prior art, a pure force-fitting connection is achieved here. This allows the relative positions of the drive wheels to be continuously predefined, as opposed to the discrete braking levels in the prior art. Therefore, the second actuator drive can be adjusted uniformly and continuously relative to the first actuator drive, and a continuous adjustment of the air gap can be performed. This is particularly advantageous for uniformly tracking the optimal operating point of the braking device and the continuous wear of the braking part during operation, i.e., the continuous wear of the brake lining. Compared with the option of only stepwise adjustment in the prior art, a consistently improved response of the braking device can be achieved, and thus the operating reliability is increased and it is easier to use.

[0051] The advantage compared to the latch couplings described in the prior art is that, for operating and releasing the coupling device, when the coupling is engaged, there is substantially no relative axial movement between the coupling elements, for example between the drive wheels or the latch elements, which must be able to move relative to each other in order to produce and release the latching form-fit. On the other hand, the pure force fit between the friction element and the counter-friction element according to the invention can be simply specified by the applied axial actuating force, wherein the friction element and the counter-friction element do not have to move axially relative to each other. This allows for a simpler and more reliable design of the coupling device.

[0052] Preferably, the friction coupling has a defined predetermined coupling torque. The coupling torque indicates the maximum differential torque that can be transmitted between the friction element and the counter-friction element by frictional adhesion in the coupling engagement. When the coupling torque is exceeded, the coupling device slips, causing the two drive wheels to rotate relative to each other. One advantage of this is that the friction coupling according to the invention slips continuously and smoothly, enabling an improved and uniform readjustment of the air gap. Additionally, as with known snap-type couplings, there is no need to design for and absorb the axial deflection movement of the latch elements.

[0053] Advantageously, the friction element and the counter-friction element are arranged coaxially. This coaxial arrangement corresponds to the coaxial arrangement of the drive wheels. The friction element and the counter-friction element can be arranged in the region of the axially opposite faces of the drive wheels with a simple design and a compact structure. Due to the generation of the pure friction connection of the coupling described above, there is no need for moving parts as in the case of snap-type couplings in the prior art.

[0054] In an advantageous design, it can be provided that the friction element and the counter-friction element are conical. The friction element can have a conical section of the cone that converges at least partially in the axial adjustment direction and a conical friction surface, which can be in the form of an outer cone or an inner cone, and the conical friction surface is designed to have a corresponding section of the cone on the counter-friction element, which is formed in a manner opposite to the inner cone or the outer cone and has a conical counter-friction surface. To produce the coupling engagement, the outer cone is inserted into the inner cone, wherein the conical friction surface and the counter-friction surface are frictionally loaded against each other by the axial operating force of the coupling. One advantage of this is that the cone allows the axial operating force of the coupling to be transmitted into a normal force acting between the conical friction surfaces at the friction contact. For example, a relatively small axial actuating force can be converted into a larger normal force at the friction contact with a shallower inclination, wherein a very high coupling torque can be achieved even with a relatively small axial actuating force of the coupling.

[0055] As an alternative to or in addition to the foregoing design, it may be provided that the friction element and the counter-friction element are planar. The corresponding friction surfaces are at least partially formed as flat axial surfaces, similar to a disk connection. This enables a space-saving arrangement, especially when only a relatively small connection torque is to be achieved.

[0056] Preferably, the friction element and the counter-friction element are preloaded against each other. Preferably, the friction element and the counter-friction element are elastically preloaded or spring-preloaded against each other. The friction surface and the counter-friction surface are pressed against each other with a predetermined axial preloading force during frictional engagement. To generate the preloading force, it may preferably be provided with an elastic preloading element, such as a spring element or the like. The connection torque of the friction connection is determined by the actuating force acting perpendicular to the friction contact, i.e., the force axially applied between the friction element and the counter-friction element. The greater the preloading force, the greater the connection torque. This provides an advantageous possibility of simply specifying the connection torque by the preloading force applied by the preloading element. For example, in the case of a spring element that is pressure-elastic in the axial direction, such as a compression spring, the applied preloading force can be simply specified and adjusted by the spring constant and the compression of the spring.

[0057] The foregoing embodiment can be advantageously achieved by the fact that the friction element and / or the counter-friction element can be axially displaced and are supported against the first drive wheel or the second drive wheel by an axially effective spring element. The friction element or the counter-friction element is, for example, torque-locked and axially displaceably connected to one of the drive wheels via a radially protruding driver, which produces a form-fit effective in the circumferential direction. The spring element axially clamped between the friction element or the counter-friction element and one of the drive wheels - which preferably takes the form of an axially effective compression spring - ensures that the friction element or the counter-friction element is axially preloaded against the corresponding counter-friction element or friction element axially supported on the other drive wheel, i.e., axially pressed against the corresponding counter-friction element or friction element for frictional contact. The corresponding counter-friction element or friction element is rotationally connected to the other drive wheel. Alternatively or additionally, the counter-friction element can also be supported on one of the drive wheels by a spring element. The advantage of this arrangement is that the friction connection according to the invention can be incorporated between the drive wheels in a simple and space-saving manner.

[0058] In an advantageous refinement, the friction element and / or the counter friction element can be arranged in the first or second drive wheel. For example, one drive wheel can be designed to be substantially drum-shaped such that the friction element or the counter friction element can be arranged in the interior enclosed by a circumferential gear or gear ring. This enables a compact design that is protected from external influences. For example, the drive wheel of the first actuator drive can have a conical friction element that axially engages in a counter friction element in the form of an inner conical part, which is at least partially arranged within the second drive wheel.

[0059] Due to the fact that the drive wheel is arranged within the axial extent of the actuator drive, i.e., the drive wheel is not mounted axially protruding on one side, a particularly compact design can be achieved - especially with the latter version.

[0060] Preferably, the friction element and / or the counter friction element have a friction facing. The friction element and the counter friction element preferably have a metallic base body, which is made of steel, for example. To avoid metal-to-metal contact, a coating or facing can preferably be applied to produce a friction pair with a defined frictional force, for example, a coating or facing made of sintered metal and / or ceramic friction material, composite material, etc. This ensures a defined and reproducible coupling torque.

[0061] It can be provided that the actuator drive has a spindle drive. In this case, a threaded spindle engages in a spindle nut in a known manner, and relative rotational drive is effected via a drive wheel connected to the threaded spindle or the spindle nut. The spindle nut can be formed as a drive-side drive element of the actuator drive, and the threaded spindle can be formed as an output element on the output side that is linearly adjustable relative thereto, or the threaded spindle can be formed as a drive-side drive element of the actuator drive, and the spindle nut can be formed as an output element on the output side that is linearly adjustable relative thereto.

[0062] The actuator can have a ball ramp arrangement, a wedge disk arrangement, or an inclined pin assembly. In a ball ramp arrangement, also known as a ramp bearing, the drive element and the output element preferably have cam plates that have tracks or ramps inclined relative to the axis, between which circumferentially rollable balls are arranged. The relative rotation causes the output element to axially displace relative to the drive element due to the balls rolling on the ramps. In a known inclined pin arrangement, inclined pins are arranged between the drive element and the output element, and the inclined pins are each supported in the circumferential direction such that they are more or less inclined relative to the axis depending on the direction of rotation during relative rotation, wherein the distance between the drive element and the output element can also be adjusted.

[0063] In an actuator, two equally acting actuator drives can be combined as a first actuator drive and a second actuator drive, for example two spindle drives. It is also possible to combine two different designs, for example a ball ramp arrangement as the first actuator drive and a spindle drive as the second actuator drive for adjusting the air gap. Here, the respective characteristic properties of each design can be optimally utilized. For example, a ball ramp arrangement can be used to achieve a non-linear adjustment characteristic with little effort, and / or at least partial self-locking properties, and / or to achieve a defined dead point or stretching position defining the adjustment distance. The implementation of the beneficial properties mentioned may at least partially require an exact specification of the air gap, which is not possible with the latch couplings in the prior art, but can be easily achieved by means of the friction coupling according to the invention.

[0064] A method for operating an electromechanical braking device is provided, the electromechanical braking device having an actuator which includes a first actuator drive and an actuator drive connected in series, and the actuator acting on a braking part which can be brought into braking application along an axial direction together with a counter-braking part, wherein the first actuator drive has a rotatably drivable first drive wheel to which a first drive torque can be applied for actuation, and the second actuator drive has a rotatably drivable second drive wheel coaxial with the first drive wheel to which a second drive torque can be applied for actuation, wherein a coupling device is arranged between the first drive wheel and the second drive wheel, it being possible to provide that the coupling device is in the form of a friction coupling and has a predetermined coupling torque, wherein when the predetermined coupling torque is exceeded, the first drive wheel slides smoothly relative to the second drive wheel, wherein, for actuating the first actuator drive, the first drive wheel and the second drive wheel are driven synchronously such that the second actuator drive remains unactuated, and for actuating the second actuator drive, the second drive wheel is driven and the first drive wheel stops relative to the second drive wheel such that the friction coupling slides and the first actuator drive remains unactuated.

[0065] The features related to the braking device mentioned above can be used individually or in combination to implement the method.

[0066] For adjusting the first actuator drive, the actuation torque can be coupled into the first drive wheel by means of a first electric servo motor, and correspondingly, the second actuator drive can be driven by a second servo motor.

[0067] In the normal braking mode, the first drive wheel and the second drive wheel rotate synchronously. On the one hand, this can be accomplished by driving the first drive wheel and the second drive wheel by a first servo motor and a second servo motor having synchronous drive torque. On the other hand, when the first drive wheel is driven, as long as the transmitted drive torque remains below the coupling torque, the second drive wheel can be carried synchronously together through the coupling device. In this operating mode, the second actuator driver remains unactuated and rotates freely as a whole together with the braking element.

[0068] Compared with the prior art, when the coupling torque is exceeded, the coupling device can slide continuously and evenly to adjust the air gap. This can be achieved, for example, by fixing the drive wheel of the first actuator driver, for example, by a brake or by appropriately controlling the first drive motor while the second drive motor applies a second drive torque greater than the coupling torque to the second drive wheel. Therefore, the second drive wheel rotates relative to the first drive wheel, and by actuating the second actuator driver, the air gap can be adjusted continuously and sensitively, so that the continuous progressive wear of the braking element or the brake lining can be optimally compensated.

[0069] The first drive wheel and the second drive wheel can be coupled in a torque-locking manner through a friction coupling to produce synchronous drive. In this case, it is not necessary to synchronously drive the two drive wheels by a servo motor. Any torque difference can be compensated within the specified tolerance.

[0070] It may be advantageous to specify a higher coupling torque when the first actuator driver is actuated compared to when the second actuator driver is actuated. The first actuator driver is actuated by the synchronous drive of the first drive wheel and the second drive wheel. The friction element and the reverse friction element are preloaded against each other by the spring force of the spring element, and in addition, the adjusting force of the first actuator driver acts in a direction opposite to the spring force. This results in a relatively high coupling torque. On the other hand, if only the second drive wheel is rotated to adjust the air gap, only the spring force acts, thus setting a lower coupling torque. This makes it easier to adjust the air gap.

[0071] In the version described above, the first actuator driver can preferably form a braking driver according to the functions given above, and correspondingly, the second actuator driver can be formed as an adjusting driver. Description of the Drawings

[0072] The advantageous embodiments of the present invention will be described in more detail below based on the drawings. Specifically:

[0073] Figure 1 A braking device according to the present invention is shown in a schematic perspective view,

[0074] Figure 2 Shown according to Figure 1Lateral view of the braking device

[0075] Figure 3 is shown separately in a schematic perspective view the positioning device according to the present invention of the braking device according to Figure 1 the braking device according to

[0076] Figure 4 shows a Q - Q cross - section through the braking device according to Figure 1 the braking device according to

[0077] Figure 5 is shown separately in a schematic perspective view the first actuator drive of the braking device according to Figure 1 the braking device according to

[0078] Figure 6 shows an enlarged detail view of the actuator from Figure 4 the actuator according to

[0079] Figure 7 from a to Figure 7 from e in shows a schematic diagram of the steps in the execution of the method according to the present invention Detailed Description

[0080] In the different figures, the same parts are always provided with the same reference numerals and are thus generally only named or mentioned once

[0081] Figure 1 Generally shown is a braking device according to the present invention, which is in the form of a disc brake. The braking device includes a brake disc 2, which forms a reaction braking part in the sense of the present invention and is connected to a vehicle wheel, which is not shown here and can rotate about a wheel axis R. A brake caliper 3 encloses two axial end faces of the brake disc 2

[0082] The brake disc 2 is here in the form of a non - ventilated brake disc made of solid material. Alternatively, the brake disc 2 can also be in the form of an internally ventilated brake disc

[0083] In Figure 3 is shown in a separate, independent schematic perspective view, and in Figures 4 to 6 is explained in detail the electric brake actuator 4 according to the present invention attached to the caliper 3

[0084] The brake actuator 4 includes an actuator 5, which extends axially in the direction of an axis A, which is parallel to the wheel axis R and indicates the adjustment direction V of the actuator 5

[0085] As in the direction along the axis A Figure 4As can be seen in the cross-sectional view, the brake disc 2 is axially arranged between two brake pads 31 and 32. One brake pad 31 is firmly supported on the brake caliper 3 on the side facing away from the brake actuator 4. The other brake pad 32, which forms the braking part in the sense of the present invention, is attached to the actuator 5 and can be adjusted by the actuator 5 in the axial adjustment direction V defined by the axis A to generate a braking application on the brake disc 2, as Figure 4 indicated by the arrow in

[0086] In the non-activated state of the braking device 1, there is an axial air gap L between the brake disc 2 and the adjustable brake pad 32, and this axial air gap L is schematically shown with an exaggerated width in Figure 4

[0087] In Figure 4 the structure of the actuator 5 is shown, and in Figure 6 its enlarged cross-section is shown.

[0088] The actuator 5 includes a first actuator driver 6 and a second actuator driver 7. The first actuator driver 6 has an inclined plane bearing, and the second actuator driver 7 is thus axially (relative to the axis A) connected in series to the first actuator driver 6 and the second actuator driver 7 has a spindle driver.

[0089] The first actuator driver 6, which is in the form of an inclined plane bearing in the example shown, includes an axially and torsionally supported cam disc 61 on the brake actuator 4 and an output-side cam disc 62. Ball bearings 63 are arranged between the cam discs 61 and 62. As can be seen in the schematic separate view in Figure 5 , the cam discs 61 and 62 have axially opposite inclined plane-shaped tracks 64 that are flat and inclined to the axis A, and the ball bearings 63 can roll between the axially opposite inclined plane-shaped tracks 64. The rotation of the output-side cam disc 62 at the top in Figure 5 relative to the driving-side fixed cam disc 61, as schematically indicated by the curved arrow, causes a linear adjustment of the output-side cam disc 62 in the adjustment direction V parallel to the axis A. Therefore, by operating the first actuator driver 6, the brake pad 32 can be brought into the braking application as shown in Figure 4

[0090] The cam disc 62 is connected to a coaxial gear 65, which is in the form of a spur gear and forms the driving wheel in the sense of the present invention.

[0091] The gear 65 is in gear engagement with the first electric servo motor 41. This enables the rotational drive of the cam disc 62 and thus the actuation of the first actuator driver 6.

[0092] ​​In the example shown, a second actuator drive 7 in the form of a spindle drive has a threaded spindle 71 on the output side, which engages in the internal thread of a spindle nut 72 on the drive side. This internal thread is formed in the output-side cam disk 62 of the first actuator drive 6, such that the functions of the output-side cam disk 62 and the drive-side spindle nut 72 are combined in one component.

[0093] The threaded spindle 71 is connected via a hub portion 74 to a coaxial gear 75, which is axially fixed and rotatably supported in the brake actuator 4. The threaded spindle is coupled to the gear 75 via a drive 73, which may for example have radially protruding projections or teeth that engage in an axial groove of the hub portion 74 in an axially displaceable manner.

[0094] The gear 75 can be in the form of a spur gear similar to the gear 65 and is arranged coaxially adjacent to the gear 65. This gear 75 is in gear engagement with a second electric servo motor 42. This enables the rotational drive of the threaded spindle 71 and thus the actuation of the second actuator drive 7.

[0095] As can be seen in Figure 4 , the threaded spindle 71 is axially connected via a thrust bearing 43, for example an axial roller bearing as shown, to a thrust piece 44 to which the displaceable brake lining 32 is attached. The thrust piece 44 can also be referred to as a piston.

[0096] The coupling device according to the invention has a friction element 8, which is oriented from the cam disk 62 to a coaxial conical attachment of the second actuator drive 7. The conical attachment has a conical friction surface 81 arranged on an outer conical piece. The friction element 81 can preferably be formed in one piece with the cam disk 62 / spindle nut 72.

[0097] The friction element 8 is frictionally coupled to a counter friction element 9 in a coupling engagement. The conical attachment is axially inserted into a corresponding conical opening of the counter friction element 9, which has a conical friction surface 91 arranged on an inner conical piece. In the coupling engagement, the friction surface 81 and the counter friction surface 91 are in frictional engagement with each other, as can be clearly seen in Figure 6 .

[0098] The counter friction element 9 is coupled to the gear 75 via a drive 92, which engages in a corresponding groove 76 in the hub portion 74 or the gear 75 in an axially displaceable manner.

[0099] The spring element 93 is arranged between the gear 75 or the hub part 74 connected to the gear 75 and the counter friction element 9. Due to the axially effective spring force of the spring element 93, the counter friction element 9 is elastically clamped against the friction element 8. Thereby, a defined coupling torque of the friction coupling according to the invention formed by the friction element 8 and the counter friction element 9 is generated.

[0100] In the second embodiment shown in the Figure 6 same view, it differs in the design and arrangement of the friction surface 81 and the counter friction surface 91, as opposed to the Figure 4 and Figure 6 conical surfaces of the first embodiment shown in, both the friction surface 81 and the counter friction surface 91 are in the form of flat axial surfaces. The functionality is basically the same, and thus the same reference numerals are used.

[0101] To operate the brake device 1, the gears 65 and 75 rotate synchronously, such that the first actuator drive 6 performs a working stroke in the adjustment direction V, such that the brake lining 32 crosses the air gap L and brakes in engagement with the brake disc 2. The synchronous drive of the gears 65 and 75 can be achieved by the drive speeds of the synchronous servo motors 41 and 42, or by driving only one of the servo motors 41 or 42 while the other servo motor 42 or 41 runs freely. In this case, the frictional coupling engagement between the friction element 8 and the counter friction element 9 ensures the synchronous rotation of the gears 65 and 75.

[0102] To adjust the width of the air gap L, for example, the gear 65 is fixed or blocked by appropriately controlling the first servo motor 41. The second servo motor 42 rotates the gear 75 relative to the gear 65, wherein the frictional coupling slides continuously and smoothly. Accordingly, the second actuator drive 7 is adjusted uniformly, which means that the width of the air gap L can also be continuously adjusted and adapted, for example, to compensate for wear on the brake lining 32.

[0103] The fact that the friction element 8 and the counter friction element 9 are arranged in whole or at least in part within the gears 65 and 75 enables a particularly compact design to be achieved.

[0104] Figures 1 to 7 The brake device shown in is in the form of a floating caliper brake also known as a sliding caliper brake. In this case, the brake lining 32 is pressed against the brake disc 2 by the thrust member 44, and the brake lining 31 is pressed against the brake disc 2 by the brake caliper 3, which can move in the direction of the axis A. Alternatively, the solution according to the invention can also be used for a fixed caliper brake.

[0105] In accordance with Figures 1 to 6In an embodiment, the first actuator drive 6 forms a brake drive or a working drive in the sense of the method according to the invention, and the second actuator drive 7 accordingly forms an adjusting drive.

[0106] In Figure 7 a) to Figure 7 e) of [], various steps of a possible implementation of the method according to the invention for operating an electromechanical brake device are schematically depicted based on the brake device 1.

[0107] Specifically, a brake lining 32 formed as a braking part and a brake disc 2 formed as a counter-braking part are shown. An air gap L is present between the brake lining 32 and the brake disc 2, and the air gap width x measured in the adjusting direction of this air gap L can be adjusted by means of the actuator drives 6 and 7.

[0108] The second actuator drive 7, i.e., the brake drive, has a constant specified adjusting distance when applying the brake. This corresponds to the air gap width B defined according to the invention. The initial position IN is spaced apart from the friction surface of the brake disc 2 by this defined air gap width B.

[0109] Figure 7 a) of [] shows an initial situation in the release position of the brake device 1 in an unadjusted state, where, for example, due to wear of the brake lining 32 and / or the brake disc 2, the air gap width x is greater than the defined air gap width B. For clarity, the deviation from the initial position IN is drawn too large.

[0110] As can be seen from the situation shown in Figure 7 a) of [], the brake lining 32 is reset by means of the second actuator drive 7, i.e., the adjusting drive, by adjusting it away from the brake disc 2, as indicated by the arrow pointing to the right. The first actuator drive 6, i.e., the brake drive, is in a rest position in which the first actuator drive 6 is reset to the maximum extent.

[0111] Resetting represents an adjustment by displacement control according to the fixed adjusting distance of the first actuator drive 6.

[0112] By resetting the brake lining 32 by means of the second actuator drive 7, the position shown in Figure 7 b) of [] is achieved. Since both actuator drives 6 and 7 are reset to the maximum extent, the maximum air gap width x is set 最大 .

[0113] As can be seen from Figure 7as seen from the position shown in b in, as indicated by the arrow pointing to the left, by actuating the first actuator drive 6, the brake lining 32 is adjusted forward towards the brake disc 2 by a specified adjustment distance B corresponding to the defined air gap width B.

[0114] This achieves Figure 7 the position shown in c in, in which the brake lining 32 is spaced apart from the brake disc 2 due to the previously mentioned wear.

[0115] From this point on, the second actuator drive 7 is activated to move the brake lining 32 further forward in the adjustment direction, as indicated by the arrow pointing to the left.

[0116] The adjustment by means of the second actuator drive 7 continues until the brake lining 32 abuts against the brake disc 2 at the brake contact K, as Figure 7 shown in d in. This position in the brake contact K corresponds to the application of the brake.

[0117] As seen from the brake contact K according to Figure 7 d in, as indicated by the arrow pointing to the right, the brake lining 32 is reset away from the brake disc 2 by an adjustment distance corresponding to the defined air gap width B by means of the first actuator drive 6. Due to the fixed adjustment distance of the first actuator, this is also an adjustment of displacement control.

[0118] Therefore, the brake lining 32 is positioned in the initial position IN in which the air gap L has the optimal air gap width B.

[0119] During subsequent braking operations, only the first actuator drive 6 is actuated, in which the adjustment is made by the magnitude of the optimal air gap width B, and an optimized brake application in the brake contact is generated, and the optimized brake application corresponds to the position according to Figure 7 d in.

[0120] To control the actuator drives 6 and 7, their actuator motors 41 and 42 are connected to an electronic control unit 45, which is schematically shown in Figure 1 and Figure 3 The electronic control unit 45 is designed to adjust the first actuator drive 6 by an amount of the defined air gap width B during a braking operation. Additionally, the control unit 45 can detect, for example, the achievement of the brake contact shown in d in by increasing the motor current of the servo motor 42 of the second actuator drive 7 when the brake lining 32 contacts the brake disc 2. Figure 7 d in.

[0121] It is also conceivable and possible to implement the method with a braking device having only one actuator drive, which has a spindle drive similar to the second actuator drive 7. Then, this also takes over the illustration according to Figure 7 b in and the reset according to Figure 7 d in and the generation of the brake contact during the subsequent braking process. Then, the brake lining 32 can be moved forward and reset by distance control of the servo motor by the control unit 45.

[0122] List of reference numerals

[0123] 1 Braking device

[0124] 2 Brake disc

[0125] 3 Caliper

[0126] 31, 32 Brake linings

[0127] 4 Brake actuator

[0128] 41, 42 Servo motors

[0129] 43 Thrust bearing

[0130] 44 Thrust piece

[0131] 45 Control unit

[0132] 5 Actuator

[0133] 6 First actuator drive (brake drive)

[0134] 61 Cam disc

[0135] 62 Cam disc (combined with spindle nut 72)

[0136] 63 Ball

[0137] 64 Track

[0138] 65 Gear

[0139] 7 Second actuator drive (adjustment drive)

[0140] 71 Threaded spindle

[0141] 72 Spindle nut (combined with cam disc 62)

[0142] 73 Drive

[0143] 74 Hub portion

[0144] 75 Gear

[0145] 76 Slit

[0146] 8 Friction element

[0147] 81 Friction surface

[0148] 9 Reverse friction element

[0149] 91 Reverse friction surface

[0150] 92 Driver

[0151] 93 Spring element

[0152] A Axis

[0153] R Wheel axis

[0154] V Adjustment direction

[0155] L Air gap

[0156] X Air gap width

[0157] B Defined air gap width

[0158] IN Initial position

[0159] K Brake contact

Claims

1. A method for operating an electromechanical braking device (1), the electromechanical braking device (1) comprising a braking part (32), a reverse braking part (2) and an electric actuator (5), in which method, for the purpose of generating a braking application, the braking part (32) is moved by means of the actuator (5) in an adjustment direction from a release position in which an air gap (L) is arranged between the braking part (32) and the reverse braking part (2), while overcoming the air gap (L) to a braking contact (K) of the reverse braking part (2). Characterized in that, before generating a braking application, the braking part (32) is positioned by the actuator (5) in an initial position (IN), in which initial position (IN) a defined air gap width (B) of the air gap (L) between the braking part (32) and the reverse braking part (2) is specified.

2. The method according to claim 1, characterized in that, A calibration routine is executed to adjust the defined air gap width (B), the calibration routine comprising the following steps: - adjusting the braking part (32) to a reference position, - adjusting the braking part (32) from the reference position to the initial position (IN).

3. The method according to claim 2, wherein The reference position is formed by the braking contact (K).

4. The method according to any one of the preceding claims, characterized in that, The reference position is detected at the braking contact (K), and then the actuator (5) is controlled so as to adjust the braking part (32) from the reference position by a specified adjustment distance to the initial position (IN).

5. The method according to any one of the preceding claims, characterized in that, The current position of the braking part (32) is detected.

6. The method according to any one of the preceding claims, characterized in that, The actuator (5) is position-controlled.

7. The method according to any one of the preceding claims, characterized in that, The actuator (5) is distance-controlled.

8. The method according to any one of the preceding claims, characterized in that, The actuator (5) comprises an actuator drive (7) and a spindle drive (71, 72) rotated by a servo motor (42).

9. The method according to any one of the preceding claims, characterized in that, The actuator (5) has a first actuator drive (6) and a second actuator drive (7) connected in series with the first actuator drive (6).

10. The method according to claim 8, wherein The initial position (IN) is set by one actuator drive (7), and a braking application is generated by the other actuator drive (6).

11. An electromechanical braking device (1) for a motor vehicle, the electromechanical braking device (1) comprising an actuator (5) and a braking part (32) connected to the actuator (5), the braking part (32) being adjustable by the actuator (5) in an adjustment direction (along an axis (A)) and being able to enter into a braking application together with a reverse braking part (2), and the electromechanical braking device (1) comprising control means (45) for controlling the actuator (5). Characterized in that, for the purpose of setting an initial position (IN), the actuator (5) can be controlled by the control means (45), in which initial position (IN) a defined air gap width (B) of the air gap (L) between the braking part (32) and the reverse braking part (2) is specified.

12. The braking device according to claim 11, wherein, The control device (45) is connected to at least one sensor device which is designed to detect the position of the actuator (5) and / or to detect the adjustment distance of the actuator (5).

13. The braking device according to any one of claims 11 to 12, characterized in that, The control device (45) is connected to at least one sensor device which is designed to detect the braking contact (K) between the braking part (32) and the counter-braking part (2).

14. The braking device according to any one of claims 11 to 13, characterized in that, The control device (45) is designed to adjust the actuator (5) to a specified position (K, IN) and / or to adjust the actuator (5) by a specified adjustment distance.

15. The braking device according to any one of claims 11 to 14, characterized in that, The control device (45) has a control input for inputting an initial value, and the control device (45) is designed to adjust the actuator (5) to an initial position (IN) corresponding to the input initial value.

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