Electromechanical brake device for a motor vehicle with switching arrangement for operating the electric motors of the brake device

Description

[0001] The invention relates to an electromechanical braking device for a motor vehicle, wherein the braking device comprises an actuating device and an associated brake element, which is adjustable along an axis by the actuating device and can be brought into brake engagement with a counter-brake element. The actuating device has a first actuating drive and a second actuating drive and, for realizing an actuating movement, comprises a first three-phase electric motor and a second three-phase electric motor with a circuit arrangement for operating the electric motors.

[0002] Such a braking device of a motor vehicle is designed as a friction brake, in which a brake element supported on the chassis and stationary relative to the rotation of the wheel to be braked can be brought into braking engagement by means of an adjusting device with a counter-braking element that rotates with the wheel. In braking engagement, a frictional contact is created between the brake element and the counter-braking element, whereby the braking torque generated by friction is greater the higher the adjusting force exerted by the adjusting device in the direction of adjustment.

[0003] A common design is the disc brake, in which the counter-braking element is formed by a brake disc rotating with the wheel, which is axially gripped on both sides by a brake caliper. A brake component, usually a brake pad, can be adjusted in an axial direction by means of at least one, preferably linear, actuating mechanism axially supported on the brake caliper, thereby bringing it into frictional contact with an axial face of the brake disc. During braking, the brake disc is frictionally clamped between the adjusted brake component and another brake component axially opposite, supported on the brake caliper.

[0004] A prerequisite for the brake to function flawlessly and respond precisely is that, in the unactuated state, a defined distance, the so-called air gap, is maintained between the brake component and the counter-brake component in the adjustment direction. When the brake is actuated, the actuating device moves the brake component perpendicular to the air gap towards the counter-brake component until the air gap is overcome and frictional contact is achieved, thus generating brake engagement.

[0005] For a reproducible and precise brake response during driving, it is crucial that the air gap, measured in the axial adjustment direction, has a defined width when the brake is not actuated. This gap width can increase during operation, for example, due to brake pad wear, and must be readjusted accordingly. DE 10 2017 123 266 A1 discloses a method for adjusting the air gap that uses an actuating device with two actuators arranged in series in the adjustment direction. Each actuator has a drive element on the input side and an output element on the output side that is linearly adjustable relative to the drive element in the axial adjustment direction. To achieve an adjustment movement, each drive element has a drive wheel that can be driven by an electric actuator motor to rotate about its axis.The rotation of the drive wheel is converted in the actuating drive into a relative adjustment movement or an actuating stroke of the output element relative to the drive element in the axial adjustment direction.

[0006] An actuating drive is a lifting or adjusting device that acts axially in the direction of adjustment. For example, an actuating drive can have a spindle drive in which the drive element has a spindle nut and the output element has a threaded spindle engaging with it, or vice versa. Other designs of actuating drives can also be used, which may include, for example, ramp bearings, cam or cam discs, rocker pin assemblies, or the like, and which also convert a rotation of the drive element into a linear adjustment of the output element.

[0007] Because the drive element of the second actuator is coupled to the output element of the first actuator, and the brake element is attached to the output element of the second actuator, actuating the first actuator linearly adjusts the brake element together with the second actuator to generate the braking action. By adjusting the second actuator independently of the actuation of the first actuator, the air gap can be adjusted. The first actuator can thus be operated continuously within its optimal operating range.

[0008] Another advantage of the two coupled actuators is that a redundant design is possible. For example, the second actuator, which is normally used only to adjust the air gap, can also be used to initiate braking. To increase reliability, it is also important that the electric motors can be controlled reliably.

[0009] Against this background, it is an object of the present invention to provide an improved electromechanical braking device, in particular with a circuit arrangement for operating the electric motors with high reliability.

[0010] To solve this problem, an electromechanical braking device according to claim 1 is proposed. Further advantageous embodiments of the invention are described in the dependent claims and the description, and are illustrated in the figures.

[0011] The proposed solution provides an electromechanical braking device for a motor vehicle comprising an actuator and an associated brake component, wherein the brake component is adjustable along an axis by the actuator and can be brought into brake engagement with a counter-brake component, and wherein the actuator has a first actuating drive and a second actuating drive, and the actuator, for realizing an adjustment movement, comprises a first three-phase electric motor and a second three-phase electric motor with a circuit arrangement for operating the electric motors. According to the invention, the circuit arrangement comprises a first control path with a first power module for controlling the first electric motor and a second control path with a second power module for controlling the second electric motor, and the circuit arrangement includes a first computing unit and a first driver stage.The first processing unit is configured to determine a target value for the electric motor based on acquired parameters and, via a driver stage, to control a power module to influence the motor currents, thus implementing the target value. The acquired parameters include, in particular, a braking target, which can be specified by a driver or a driver assistance system, and the current speed of the vehicle. Advantageously, each power module comprises an inverter, preferably a bridge circuit made of MOSFETs (MOSFET: metal-oxide-semiconductor field-effect transistor) for controlling the respective electric motor. Furthermore, each power module can advantageously include a phase separation unit, preferably with a phase relay for each phase of the respective electric motor.Furthermore, the respective power module advantageously includes a PWM controller (PWM: pulse width modulation). With such a circuit arrangement, the electric motors can be operated with high reliability and high fault tolerance.

[0012] A particularly advantageous embodiment of the braking device provides that the second actuating drive is coupled in series with the first actuating drive, wherein the first actuating drive has a rotatably driven first drive wheel, and the second actuating drive has a rotatably driven second drive wheel that is coaxial with the first drive wheel, wherein a coupling device is arranged between the first drive wheel and the second drive wheel, and wherein the coupling device is designed as a friction clutch with a friction element that can be frictionally connected to a counter-friction element in the clutch engagement, wherein the first electric motor enables actuation of the first actuating drive and the second electric motor enables actuation of the second actuating drive. Hereinafter, the first and the second drive wheels are sometimes referred to together as the two drive wheels or simply as the drive wheels.The drive wheels can be designed as a gear, in particular as a spur gear, or as a belt or toothed belt wheel or worm gear, so that advantageously a gear wheel is provided via which a drive torque from the respective electric motor can be coupled into the actuating drive.

[0013] Preferably, a friction clutch is implemented between the drive wheels. This clutch comprises a friction element that is torque-locked to one of the drive wheels and a corresponding counter-friction element that is torque-locked to the other drive wheel. The friction element can be brought into frictional engagement with the counter-friction element at any relative angular position. Preferably, a purely force-locking clutch is implemented. This allows the relative position of the drive wheels to be advantageously continuously preset. Accordingly, a uniform, continuous adjustment of the second actuating mechanism relative to the first actuating mechanism is possible, and continuous adjustment of the air gap can be achieved.This is particularly advantageous with regard to the consistent adjustment of the optimal operating point of the braking device to the continuous wear of the brake component during operation, i.e., the continuous wear of the brake lining. This allows for a consistently improved response of the braking device, resulting in increased operational safety and greater ease of use. Furthermore, it is advantageous that essentially no axial relative movement is required between the coupling elements engaged in the coupling device, for example, between the drive wheels or the detent elements, which would otherwise necessarily have to be movable relative to each other to create and release the locking positive connection.In contrast, the pure frictional connection between the friction and counter-friction elements can be simply determined by the applied axial actuating force, without requiring axial movement of the friction and counter-friction elements relative to each other. This allows for a simpler and more reliable design of the coupling device.

[0014] According to a further advantageous embodiment, the circuit arrangement is configured to control the first electric motor and the second electric motor using the first processing unit and the first driver stage. In particular, one embodiment provides that the first processing unit is configured to determine a first setpoint for the first electric motor and a second setpoint for the second electric motor based on the received parameters, and that the first driver stage controls both the first power module assigned to the first electric motor and the second power module assigned to the second electric motor to influence the motor currents, such that the first setpoint is implemented by the first electric motor and the second setpoint is implemented by the second electric motor.Advantageously, with this design, if one of the electric motors fails, the other electric motor can still be controlled to generate a braking intervention.

[0015] A further advantageous embodiment provides that the circuit arrangement additionally comprises a second driver stage, wherein the first driver stage is advantageously assigned to the first control path, and the second driver stage is advantageously assigned to the second control path. Preferably, the circuit arrangement is configured such that the first processing unit is designed to determine, based on the received parameters, a first setpoint for the first electric motor and a second setpoint for the second electric motor, and to control the first power module via the first driver stage and the second power module via the second driver stage to influence the motor currents, such that the first setpoint is implemented by the first electric motor and the second setpoint is implemented by the second electric motor.Advantageously, the first and second driver stages are interconnected in such a way that, in the event of a failure of the second driver stage, the first power module and the second power module can still be controlled via the first driver stage. Furthermore, it is advantageous to configure the first and second driver stages in such a way that, in the event of a failure of the first driver stage, the first power module and the second power module can still be controlled via the second driver stage. The driver stages are thus redundant, advantageously increasing reliability. Preferably, a monitoring unit associated with the circuit arrangement is designed to detect a malfunction of the first and / or second driver stage.Advantageously, in this design, if one of the driver stages fails, the electric motors can still be controlled via the still functional driver stage to generate a braking intervention.

[0016] As a further advantageous embodiment, the circuit arrangement comprises a second driver stage and a second processing unit, wherein the first driver stage and the first processing unit are advantageously assigned to the first control path, and the second driver stage and the second processing unit are advantageously assigned to the second control path. Advantageously, the second processing unit, in particular like the first processing unit, is configured to determine a setpoint for the electric motor based on acquired parameters and to control a power module for influencing the motor currents via a driver stage, thus implementing the setpoint for the electric motor.In particular, it is provided that, under fault-free operation, the first processing unit determines a first target value for the first electric motor based on acquired parameters and, via the first driver stage, controls the first power module to influence the motor currents of the first electric motor in order to implement the first target value. Furthermore, under fault-free operation, it is provided that the second processing unit determines a second target value for the second electric motor based on acquired parameters and, via the second driver stage, controls the second power module to influence the motor currents of the second electric motor in order to implement the second target value.In the event of a malfunction in the first processing unit, the second processing unit is advantageously also configured to determine a first target value for the first electric motor and to control the first electric motor accordingly via the first control path. Similarly, in the event of a malfunction in the second processing unit, the first processing unit is advantageously also configured to determine a second target value for the second electric motor and to control the second electric motor accordingly via the second control path. In this way, two independently usable control paths are advantageously created, which further ensures that, in the event of a malfunction in one of the control paths, the corresponding electric motor can continue to be operated via the other control path, and thus braking intervention can be implemented despite a malfunction.Preferably, the first control path and the second control path are configured redundantly. In particular, it can also be provided that one of the processing units, especially the first processing unit, is designated as the master processing unit, which, in normal operation, determines the first and second setpoints for the electric motors and controls the first electric motor via the first control path and the second electric motor via the second control path, wherein the second processing unit, which in this case may be configured to be less powerful than the first processing unit, checks the plausibility of the setpoints determined by the first processing unit.Advantageously, if a functional impairment is detected with regard to the first computing unit, the target values ​​are determined by the second computing unit and the second computing unit takes over the control of the first and second electric motors via the respective control path.

[0017] In particular, in the configuration where the circuit arrangement comprises a first processing unit and a first driver stage in the first control path, and a second processing unit and a second driver stage in the second control path, the first processing unit is configured to control the first power module for influencing the motor currents of the first electric motor via the first driver stage, and the second processing unit is configured to control the second power module for influencing the motor currents of the second electric motor via the second driver stage. It is further advantageous that the first processing unit is further configured to control the first power module for influencing the motor currents of the first electric motor via the first driver stage and to control the second power module for influencing the motor currents of the second electric motor via the second driver stage.A further advantage of the second processing unit is its ability to control the second power module for influencing the motor currents of the second electric motor via the second driver stage, and to control the first power module for influencing the motor currents of the first electric motor via the first driver stage. A failure of the first processing unit can thus be advantageously compensated for by the second processing unit, and vice versa.

[0018] According to a further advantageous embodiment, a first rotor position sensor is assigned to the first electric motor and a second rotor position sensor is assigned to the second electric motor. The first rotor position sensor is advantageously connected to the first and / or the second processing unit for transmitting rotor position signals, and the second rotor position sensor is also advantageously connected to the first and / or the second processing unit for transmitting rotor position signals. Advantageously, the rotor position signals are further parameters that the first processing unit acquires, or that the first and second processing units acquire, in order to determine a target position for the electric motor.In particular, it is provided that the first rotor position sensor is connected to the first processing unit for transmitting rotor position signals, and that the first processing unit is configured to forward these rotor position signals to the second processing unit. Furthermore, it is advantageous that the second rotor position sensor is connected to the second processing unit for transmitting rotor position signals, and that the second processing unit is configured to forward these rotor position signals to the first processing unit.

[0019] Furthermore, an advantageous embodiment of the braking device provides that the first control path includes a first connection element for connection to a motor vehicle's voltage source as an energy source, and / or the second control path includes a second connection element for connection to a motor vehicle's voltage source as an energy source. These connection elements allow, in particular, connection to a motor vehicle's energy source, especially a vehicle battery. Preferably, the first control path is supplied with energy from the vehicle's energy source via the first connection element, and the second control path is supplied with energy from the vehicle's energy source via the second connection element. This redundancy advantageously further improves reliability.Advantageously, an EMI filter (EMI: electromagnetic interference) is assigned to the first connection element and / or an EMI filter is assigned to the second connection element.

[0020] According to a further advantageous embodiment, the first control path comprises a first interface for connection to a communication channel, in particular a CAN bus, of a motor vehicle, and / or the second control path comprises a second interface for connection to a communication channel, in particular a CAN bus, of a motor vehicle. Vehicle parameters, in particular a braking command and / or a current vehicle speed, can be provided to the first and / or second processing unit via this first and / or this second interface, and these parameters are taken into account when determining the target speed of the electric motor. This redundancy advantageously further improves fault tolerance.

[0021] Advantageously, the first control path includes a third interface for connecting to a wheel speed sensor, and / or the second control path includes a third interface for connecting to a wheel speed sensor. These interfaces can advantageously transmit sensor signals from the wheel speed sensor as an additional parameter to the first processing unit and / or the second processing unit.

[0022] According to a further advantageous embodiment, the first control path comprises a transceiver unit and / or the second control path comprises a transceiver unit. The transceiver unit is advantageously configured for data exchange between the respective computing unit and the motor vehicle, in particular via the first interface and / or the second interface.

[0023] Regarding an embodiment of the brake device in which a clutch designed as a friction clutch is provided between a first drive wheel and a second drive wheel, the friction clutch preferably has a defined, predefinable clutch torque. The clutch torque indicates the maximum differential torque that can be positively transmitted between the friction element and the counter-friction element by friction during clutch engagement. When the clutch torque is exceeded, the clutch slips, causing the two drive wheels to rotate relative to each other. An advantage of this is that the friction clutch according to the invention slips continuously, thus enabling improved, uniform readjustment of the air gap. Furthermore, there is no need to consider and compensate for axial deflection movements of detent elements in the design.

[0024] It is advantageous for the friction element and the counter-friction element of the coupling device to be arranged coaxially. This coaxial arrangement advantageously corresponds to the coaxial arrangement of the drive wheels. The friction element and the counter-friction element can be arranged in a simple and compact design in the area of ​​the axially opposing end faces of the drive wheels. Due to the purely frictional transmission of the coupling described above, no moving parts are required.

[0025] In an advantageous embodiment, the friction element and the counter-friction element can be conical. The friction element can have a conical section, converging at least partially in the axial adjustment direction, with a conical friction surface. This conical section can be configured as an outer or inner cone. The counter-friction element can be configured as an inner or outer cone, converging in the opposite direction, and has a conical counter-friction surface. To generate the clutch engagement, the outer cone engages with the inner cone, whereby the conical friction and counter-friction surfaces are frictionally engaged against each other by an axial actuating force of the clutch. An advantage of this design is that the cone allows the axially acting actuating force of the clutch to be converted into the normal force acting between the conical friction surfaces in frictional contact.Thus, a shallower slope allows a relatively small axial actuating force to be converted into a larger normal force in the friction contact, making it possible to achieve a high clutch torque even with a relatively small axial actuating force of the clutch.

[0026] Alternatively or additionally to the aforementioned design, the friction element and the counter-friction element can be planar. In this case, the corresponding friction surfaces are preferably designed, at least partially, as planar axial surfaces, similar to a disc clutch. This allows for a space-saving arrangement, particularly when only a relatively small clutch torque is required.

[0027] It can be provided, in particular, that the friction element and the counter-friction element are preloaded against each other. Preferably, the friction element and the counter-friction element are elastically or resiliently preloaded against each other. The friction and counter-friction surfaces are pressed against each other in frictional engagement with a predetermined axial preload force. An elastic preload element, in particular a spring element or the like, can preferably be provided to generate the preload force. The coupling torque of the friction clutch is determined by the actuating force acting perpendicular to the friction contact, i.e., the force applied axially between the friction and counter-friction elements, whereby the coupling torque is greater the greater the preload force. This offers the advantageous possibility of simply specifying the coupling torque by the preload force exerted by the preload element.For example, in the case of an axially elastic spring element, in particular a compression spring, the applied preload force can be easily determined and adjusted by the spring constant and the compression of the spring.

[0028] The aforementioned embodiment can advantageously be realized by making the friction element and / or the counter-friction element axially displaceable and supported against the first or second drive wheel by an axially acting spring element. The friction element or the counter-friction element is connected to one of the drive wheels in a torque-locking and axially displaceable manner, in particular by radially projecting drivers that generate a positive locking engagement in the circumferential direction. The spring element, which is preferably designed as an axially acting compression spring and is axially clamped between the friction element or the counter-friction element and one of the drive wheels, ensures that the friction or counter-friction element is axially pre-tensioned against the corresponding counter-friction or friction element, which is axially supported on the other drive wheel, i.e., pressed axially against it in frictional contact.The corresponding counter-friction or friction element is rotationally connected to the other drive wheel. Alternatively or additionally, the counter-friction element may be supported on one of the drive wheels by a spring element. An advantage of this arrangement is that the friction clutch according to the invention can be integrated between the drive wheels in a structurally simple and space-saving manner.

[0029] In an advantageous embodiment, 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 essentially drum-shaped, so that the friction or counter-friction element can be arranged in an interior enclosed by the rotating gear or ring gear. This enables a compact design protected against external influences. For example, the drive wheel of the first actuating drive can have a conical friction element that engages axially with a counter-friction element designed as an internal cone, which is at least partially located inside the second drive wheel.

[0030] A particularly compact design can be achieved – especially in the last-mentioned version – by arranging the drive wheels within the axial extent of the actuating drives, i.e., not protruding axially on one side.

[0031] It is preferred that the friction element and / or the counter-friction element have a friction lining. The friction and counter-friction elements preferably have a metallic base body, in particular made of steel. To prevent metal-to-metal contact, a coating or lining can preferably be applied to create a friction pair with a defined frictional force, in particular made of sintered, metallic, and / or ceramic friction materials, composite materials, or the like. This ensures a defined, reproducible coupling torque.

[0032] A further advantageous feature of an actuating drive is a spindle drive, which is advantageously driven by one of the electric motors. In the spindle drive, a threaded spindle engages in a spindle nut in a manner known per se, and a relative rotating drive is driven via a drive wheel connected to the threaded spindle or the spindle nut. According to one embodiment, the spindle nut forms the drive-side drive element of the actuating drive, and the threaded spindle forms the output-side driven element, which is linearly adjustable relative to it. Another embodiment is configured accordingly in reverse.

[0033] Another embodiment provides for an actuating drive with a ball ramp arrangement, a wedge disc arrangement, or a rocker pin arrangement. In a ball ramp arrangement, also known as a ramp bearing, the drive and driven elements preferably have cam discs with raceways or ramps inclined to the axis, between which circumferentially rolling balls are arranged. A relative rotation, due to the balls rolling on the ramps, causes the driven element to be axially displaced relative to the drive element. In a rocker pin arrangement, which is known per se, rocker pins are arranged between the drive and driven elements and supported circumferentially in such a way that, depending on the direction of rotation, they are inclined more or less to the axis during a relative rotation, thereby also allowing the distance between the drive and driven elements to be adjusted.

[0034] In a further embodiment of the adjusting device, two identically acting actuators are advantageously combined as first and second actuators, in particular two spindle drives. However, according to another advantageous embodiment, it is also possible to combine two different designs, in particular a ball ramp arrangement as the first actuator and a spindle drive as the second actuator for adjusting the air gap. This allows the respective characteristic properties of each design to be optimally utilized. In particular, a ball ramp arrangement can be used to achieve a non-linear adjustment characteristic with minimal effort, and / or at least partially self-locking properties, and / or a defined dead center or extended position that enables a defined adjustment range.The realization of the aforementioned positive properties may require, at least in part, a precise specification of the air gap, which can be achieved using the proposed friction coupling.

[0035] To operate an electromechanical braking device in a motor vehicle, in particular a braking device designed according to the invention, it is provided that a braking requirement is detected and, taking into account at least one further parameter of the motor vehicle, a target value for the first electric motor and / or the second electric motor is determined and the first electric motor and / or the second electric motor is controlled via a control path with a driver stage and a power module to implement the determined target value.

[0036] In particular, the brake device provided for the method of operating the brake device comprises an actuating device and an associated brake element, which is adjustable by the actuating device along an axis and can be brought into brake engagement with a counter-brake element, wherein the actuating device has a first actuating drive and a second actuating drive, and the actuating device for realizing an actuating movement comprises a first three-phase electric motor and a second three-phase electric motor with a circuit arrangement for operating the electric motors, wherein the circuit arrangement comprises a first control path with a first power module for controlling the first electric motor and a second control path with a second power module for controlling the second electric motor, and wherein the circuit arrangement comprises a first computing unit and a first driver stage, wherein the first computing unit is configuredto determine a target value for the electric motor based on recorded parameters and to control a power module via a driver stage to influence the motor currents, so that the target value for the electric motor is implemented.

[0037] In a method for operating an electromechanical brake device, which has an actuating device comprising a first actuating drive and an actuating drive serially coupled thereto, and which acts on a brake element that can be brought into brake engagement with a counter-brake element in the direction of an axis, wherein the first actuating drive has a rotatably driven first drive wheel onto which a first drive torque can be applied for actuation, in particular by means of the first electric motor, and the second actuating drive has a rotatably driven second drive wheel coaxial with the first drive wheel onto which a second drive torque can be applied for actuation, in particular by means of the second electric motor, wherein a coupling device is arranged between the first drive wheel and the second drive wheel, it is advantageously provided thatthat the clutch device is designed as a friction clutch and has a predefinable clutch torque, upon exceeding which the first drive wheel slips relative to the second drive wheel, wherein, to actuate the first actuating drive, the first drive wheel and the second drive wheel are driven synchronously, so that the second actuating drive remains unactuated, and, to actuate the second actuating drive, the second drive wheel is driven, and the first drive wheel is stationary relative to it, so that the friction clutch slips and the first actuating drive remains unactuated. The features mentioned above in connection with the brake device according to the invention can be used individually and in combination to implement the proposed method. To adjust the first actuating drive, the first three-phase electric motor, in particular a first electric actuator, is used.A torque is coupled into the first drive wheel. Accordingly, the second actuator is driven by the second three-phase electric motor, in particular a second electric actuator motor.

[0038] In normal braking operation, the first and second drive wheels rotate synchronously. This can be achieved either by driving the first and second drive wheels with synchronized drive torques from the first and second electric motors, respectively, or by synchronizing the second drive wheel's rotation via the clutch mechanism when the first drive wheel is driven, provided the transmitted drive torque remains below the clutch torque. In this operating mode, the second actuator remains disengaged and rotates freely along with the brake element.

[0039] According to a further advantageous embodiment, in a method for operating a service brake, the clutch device can continuously and uniformly slide through the air gap when the clutch torque is exceeded. This is achieved in particular by locking the drive wheel of the first actuating mechanism, especially by a brake or a corresponding control of the first electric motor, while a second drive torque, greater than the clutch torque, is applied to the second drive wheel by the second electric motor. This rotates the second drive wheel relative to the first drive wheel, and by actuating the second actuating mechanism, the air gap can be continuously and precisely adjusted, thus optimally compensating for the continuously progressing wear of the brake element or brake lining.

[0040] A further advantageous embodiment of the method provides that the first and second drive wheels are torque-locked via the friction clutch to generate a synchronous drive. In this case, synchronous drive of the two drive wheels by the electric motors is not required. Any torque differences can be compensated for within predefined tolerances.

[0041] It can be advantageous to provide a higher coupling torque when the first actuating mechanism is engaged than when the second actuating mechanism is engaged. The first actuating mechanism is engaged by the synchronous drive of the first and second drive wheels. The friction element and the counter-friction element are pre-tensioned against each other by the spring force of the spring element, and the adjusting force of the first actuating mechanism acts in opposition to the spring force. This results in a relatively high coupling torque. If, however, only the second drive wheel is rotated to adjust the air gap, only the spring force acts, resulting in a lower coupling torque. This simplifies the adjustment of the air gap.

[0042] Further advantageous details, features and embodiments of the invention are explained in more detail in connection with the exemplary embodiments illustrated in the figures (hereinafter referred to in particular as Fig.: figure). The figures show: Fig. 1 shows an embodiment of a brake device designed according to the invention in a schematic perspective view; Fig. 2 shows a side view of the brake device according to the invention. Fig. 1 Fig. 3 shows an embodiment of an actuating device of the brake device designed according to the invention. Fig. 1 isolated in a schematic perspective view; Fig. 4 a section QQ through the brake device according to Fig. 1 ; Fig. 5 the first actuating drive of the brake device according to Fig. 1 isolated in a schematic perspective view; Fig. 6 an enlarged detail view of the adjusting device made of Fig. 4; and Fig. 7 an embodiment of a circuit arrangement designed according to the invention for operating the electric motors of a brake device designed according to the invention.

[0043] In the various figures, identical parts are usually marked with the same reference symbols and are therefore sometimes only explained in connection with one of the figures.

[0044] With reference to Figs. 1 to 6 First, an advantageous structural design of an exemplary embodiment for a brake device 1 designed according to the invention is described, with reference to Fig. 7 An advantageous embodiment of a circuit arrangement 100 for operating the first electric motor 41 and the second electric motor 42 of the brake device 1 in a motor vehicle is described.

[0045] For example, a two-wheeled vehicle, which may be a motorcycle, can have a brake device 1 for each wheel. Similarly, a four-wheeled vehicle, which may be a passenger car, truck, or bus, can have a brake device 1 for each wheel. Preferably, each brake device 1 has its own switching device 100; that is, each brake device 1 has its own switching arrangement 100, which is separate and independent from the switching arrangements 100 of the other brake devices 1. In particular, it is provided that the switching arrangements 100 of the brake devices 1 can exchange data with each other, especially regarding the wheel speed of the wheel assigned to the respective brake device 1 and / or a malfunction of one of the brake devices 1.

[0046] Fig. 1Figure 1 shows the brake device 1 as a whole, which is designed as a disc brake. In this embodiment, the brake device 1 comprises a brake disc 2, which forms a counter-brake element and, when used as intended in a motor vehicle, is connected to a vehicle wheel (not shown) that rotates about a wheel axle R. A brake caliper 3 engages the two axial end faces of the brake disc 2. In this embodiment, the brake disc 2 is designed as an unventilated brake disc made of solid material. According to an embodiment not shown here, it can also be designed as an internally ventilated brake disc.

[0047] An electric brake actuator 4 is attached to the brake caliper 3 of the brake device 1, which is in Fig. 3 shown in a separate, isolated schematic perspective view, and with reference to Figs. 4 to 7The brake actuator 4 comprises an actuating device 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 actuating device 5.

[0048] As shown in the sectional view of Fig. 4 As can be seen along axis A, the brake disc 2 is arranged axially between two brake pads 31 and 32. One brake pad 31 is fixedly supported on the brake caliper 3 on the side facing away from the brake actuator 4. The other brake pad 32, which forms a brake component according to the invention, is attached to the adjusting device 5 and can be adjusted by it in the axial adjustment direction V given by axis A to generate the brake engagement on the brake disc 2, as shown in Fig. 4 as indicated by the arrow. In the unactuated state of the brake device 1, there is an axial air gap L between the brake disc 2 and the adjustable brake pad 32, which is Fig. 4 is drawn schematically in an exaggeratedly wide way.

[0049] The construction of the adjusting device 5 is in Fig. 4 and in the enlarged section thereof in Fig. 6 The actuating device 5 comprises a first actuating drive 6, which has a ramp bearing, and a second actuating drive 7, which has a spindle drive and is axially coupled to it in series, here axially with respect to axis A. The first actuating drive 6, which in the illustrated embodiment is designed as a ramp bearing, comprises an drive-side cam disk 61 and an output-side cam disk 62, which are axially and rotationally fixed to the brake actuator 4. Balls 63 are arranged between the cam disks 61 and 62. As shown in the schematically isolated view of Fig. 5As can be seen, the cam discs 61 and 62 have axially opposing, ramp-like raceways 64, inclined to axis A, between which balls 63 can roll. A rotation of the output-side cam disc 62, in Fig. 5 The upward movement, relative to the stationary drive-side cam disk 61 – as schematically indicated by the curved arrows – leads to a linear adjustment of the driven-side cam disk 62 in the adjustment direction V parallel to the axis A. This allows the brake pad 32, as shown in Fig. 4 shown, by actuating the first actuating drive 6, which is brought into brake engagement.

[0050] The cam disk 62 is connected to a coaxial gear 65, which is designed as a spur gear and forms a drive gear. The gear 65 is engaged with a first three-phase electric motor 41, which here is designed as an actuator motor and can in particular be a permanent magnet synchronous motor. This first electric motor 41 enables the rotational drive of the cam disk 62 and thus the actuation of the first actuator 6. A circuit arrangement, as described in particular below with reference to Fig. 7 As explained in more detail, the first electric motor 41 is operated.

[0051] The second actuating drive 7, which in the example shown is designed as 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 input side. This internal thread is formed in the output-side cam disk 62 of the first actuating drive 6, so that the functions of the output-side cam disk 62 and the input-side spindle nut 72 are advantageously combined in one component. The threaded spindle 71 is connected via a hub part 74 to a coaxial gear 75, which is rotatably mounted axially fixed in the brake actuator 4. The threaded spindle is torque-locked but axially displaceable to the gear 75 via drivers 73, which in particular have radially projecting projections or teeth that engage axially displaceably in axial slots of the hub part 74. The gear 75 can be designed as a spur gear like the gear 65 and is arranged coaxially adjacent to it.This gear 75 is engaged with a second three-phase electric motor 42, which is designed here as an actuator motor and can in particular also be a permanent magnet synchronous motor. This second electric motor enables the rotary drive of the threaded spindle 71 and thus actuation of the second actuator 7, whereby this second electric motor 42 is also controlled via the circuit arrangement already mentioned, as described in particular below with reference to [reference to figure]. Fig. 7 It is explained in more detail how it is operated.

[0052] The threaded spindle 71 is axially connected via a thrust bearing 43, in particular an axial roller bearing as shown, to a pressure piece 44, to which the movable brake pad 32 is attached, as shown in Fig. 4 This is recognizable. The pressure piece 44 can also be referred to as a piston.

[0053] The clutch assembly of the brake assembly 1 has a friction element 8, which is directed as a coaxial, conical projection from the cam disc 62 towards the second actuating drive 7. The conical projection has a conical friction surface 81 arranged on the outside of an outer cone. The friction element 81 can preferably be formed integrally with the cam disc 62 / spindle nut 72.

[0054] The friction element 8 is frictionally coupled to a counter-friction element 9 in the clutch engagement. The conical projection of the counter-friction element 9 engages axially in a corresponding conical opening, which has a conical friction surface 91 arranged in an inner cone. In the clutch engagement, the friction surface 81 and the counter-friction surface 91 are in frictional contact with each other, as shown in Fig. 6The counter-friction element 9 is recognizably coupled to the gear 75 via drivers 92, which engage axially displaceably in corresponding slots 76 in the hub part 74 or the gear 75. The coupling is torque-locked but axially displaceable. A spring element 93 is arranged between the gear 75 or the hub part 74 connected to it and the counter-friction element 9. Its axially acting spring force elastically preloads the counter-friction element 9 against the friction element 8. This generates a defined coupling torque for the friction coupling formed by the friction element 8 and the counter-friction element 9.

[0055] To actuate the brake device 1, gears 65 and 75 are rotated synchronously, causing the first actuating drive 6 to perform a working stroke in the adjustment direction V. This allows the brake pad 32 to pass through the air gap L and engage with the brake disc 2. The synchronous drive of gears 65 and 75 can be achieved by synchronizing the drive speeds of the first electric motor 41 and the second electric motor 42, or by using only one of the electric motors 41 or 42, while the other electric motor 42 or 41 runs freely. In this case, the frictional engagement between the friction element 8 and the counter-friction element 9 ensures synchronous rotation of gears 65 and 75.

[0056] To adjust the width of the air gap L, the gear 65 is locked or blocked, in particular by appropriately controlling the first electric motor 41. The second electric motor 42 rotates the gear 75 relative to the gear 65, causing the friction clutch to continuously slip. The second actuating drive 7 is adjusted accordingly, allowing the width of the air gap L to be continuously set and adjusted, for example, to compensate for wear of the brake lining 32.

[0057] By arranging the friction element 8 and the counter-friction element 9 wholly or at least partially within the gears 65 and 75, a particularly compact design can be achieved.

[0058] The in Figs. 1 to 6The brake devices 1 shown are designed as floating caliper brakes, also known as floating caliper brakes. In this design, the brake pad 32 is pressed against the brake disc 2 by the pressure piece 44, and the brake pad 31 is pressed against the brake disc 2 by the brake caliper 3, which is displaceable relative to the brake disc 2 in the direction of axis A. Alternatively, the proposed solution can also be used with a fixed caliper brake.

[0059] An advantageous circuit arrangement 100 for operating the electric motors 41, 42 of the actuating device 5 and its architecture is described in Fig. 7The circuit arrangement 100 is shown as a block diagram. In this embodiment, the circuit arrangement 100 comprises a first control path 101 with a first processing unit 107, a first driver stage 105, and a first power module 103 for controlling the first electric motor 41 and, if required, for controlling the second electric motor 42. Furthermore, the first control path 101 includes a first connection element 111 for connecting to a power source of a motor vehicle, a first interface 113 for connecting to a communication bus of a motor vehicle, and a third interface 115 for connecting a wheel speed sensor of a motor vehicle. The energy required for operation is supplied to the first processing unit 107, which is designed in particular as a microcontroller circuit, the first driver circuit 105, and the first power module 103 via an EMI filter 121.To determine a target value for the electric motor, the first processing unit 107 is configured to receive a variety of data. For example, the first processing unit 107 can receive rotor position signals from a rotor position sensor 109 assigned to the first electric motor 41. Furthermore, the processing unit 107 is configured to receive a sensor signal from a wheel speed sensor as an additional parameter via the third interface 115. Additional vehicle parameters, such as a braking command specified by a vehicle user or a driver assistance system, or the current vehicle speed, can be received by the processing unit 107 via a transceiver unit 124 through the first interface 113 via a communication bus of the vehicle, in particular a CAN bus. Data can also be transmitted to the communication bus via the transceiver unit 124 and the first interface 113.The first computing unit 107 can receive further data from the first power module 103.

[0060] In this embodiment of the circuit arrangement 100, the circuit arrangement 100 comprises a second control path 102 that is essentially completely redundant with respect to the first control path 101. This second control path 102 therefore includes a second processing unit 108, a second driver stage 106, and a second power module 104 for controlling the second electric motor 42 and, if necessary, for controlling the first electric motor 41. The second control path 102 is further equipped with a second connection element 112 for connecting to a power source of a motor vehicle, a second interface 114 for connecting to a communication bus of a motor vehicle, and a fourth interface 116 for connecting a wheel speed sensor of a motor vehicle.The energy required for operation is supplied to the second processing unit 108, which is also designed as a microcontroller circuit, the second driver circuit 106, and the second power module 104 via an EMI filter 121. To determine a target value for the electric motor, the second processing unit 108 is configured to receive a variety of data. For example, the second processing unit 108 can receive rotor position signals from a rotor position sensor 110 assigned to the second electric motor 42. In addition, the second processing unit 108 is configured to receive a sensor signal from a wheel speed sensor as a further parameter via the fourth interface 116.The second processing unit 108 can receive further vehicle parameters, such as a braking command specified by a vehicle user or a driver assistance system, or the current speed of the vehicle, via a transceiver unit 124 through the second interface 114 via a communication bus of the vehicle, in particular a CAN bus, whereby data can also be transmitted to the communication bus via the transceiver unit 124 and the second interface 114. The second processing unit 108 can also receive further data from the second power module 104.

[0061] In normal operation, the first processing unit 107 determines a target value for the first electric motor 41, and the second processing unit 108 determines a target value for the second electric motor 42. Via the first driver stage 105, the first processing unit 107 controls the first power module 103 to influence the motor currents, so that the target value determined for the first electric motor 41 is implemented by the first electric motor 41. Similarly, the second processing unit 108 controls the second power module 104 via the second driver stage 106, so that the target value determined by the second processing unit 108 is implemented by the second electric motor 42.

[0062] In this embodiment, the first processing unit 107 and the second processing unit 108 are also connected to each other via a signal link 130 for signal exchange, so that signals can be exchanged between the first control path 101 and the second control path. This signal link 130 allows, in particular, the control to be taken over solely by the still-functioning processing unit if a malfunction is detected in one of the processing units. The data and parameters necessary to determine the setpoint for the electric motor of the control path whose processing unit is malfunctioning are provided to the functioning processing unit via the signal link 130. However, as explained above, it is also possible to implement a brake intervention by controlling only one electric motor.

[0063] According to a more cost-effective design variant, indicated here only by means of the signal connection 131, the circuit arrangement 100 can also comprise only a first computing unit 107. The second computing unit 108 would then be omitted. In this design variant, the necessary data and parameters are then transmitted directly to the first computing unit 107, then directly via a signal connection 131 through the second driver stage 106 to control the second power module 104 and, via that, the second electric motor 42.

[0064] According to an even more cost-effective design variant, which is also only indicated here by means of a further signal connection 132, in addition to the second computing unit 108, the second driver stage 106 is also omitted, whereby the first computing unit 107 is configured in this case to control the second power module 104 and thus the second electric motor 42 via the first driver stage 105.

[0065] Since the control paths 101, 102 of the circuit arrangement 100 are designed redundantly and, in addition, a braking intervention can even be implemented using only one of the electric motors 41, 42, a particularly high level of reliability is ensured.

[0066] The embodiments shown in the figures and explained in connection with them serve to illustrate the invention and are not limiting to it. Reference symbol list

[0067] 1Brake device 2Brake disc (counterbrake part) 3Brake caliper 31, 32Brake pad (brake part) 4Brake actuator 41, 42first,second electric motor 43 thrust bearing 44 pressure piece 5 adjusting device 6 first adjusting drive 61 cam disc 62 cam disc (integrated with spindle nut 72) 63 ball 64 raceway 65 gear (first drive gear) 7 second adjusting drive 71 threaded spindle 72 spindle nut (integrated with cam disc 62) 73 driver 74 hub part 75 gear (second drive gear) 76 slot 8 friction element 81 friction surface 9 counter friction element 91 counter friction surface 92 driver 93 spring element 100 circuit arrangement 101 first control path 102 second control path 103 first power module 104 second power module 105 first driver stage 106 second driver stage 107 first computing unit 108 second computing unit 109 first Rotor position sensor 110 Second rotor position sensor 111 First connection element 112 Second connection element 113 First interface 114 Second interface 115 Third interface 116 Fourth interface 121 EMI filter 124 Transceiver unit 130 Communication link between the computing units (107,108) 131 Connection between first computing unit (107) and second driver stage (106) 132 Connection between first computing unit (107) and second power module (108) A Axis R Wheel axis V Direction of adjustment L Air gap,

Claims

1. An electromechanical braking device (1) for a motor vehicle comprising a positioning device (5) and a brake part (32) connected thereto, which is displaceable by the positioning device (5) along an axis (A) and can be brought into braking engagement with a counter brake part (2), wherein the positioning device (5) has a first positioning drive (6) and a second positioning drive (7) and the positioning device (5), to implement a displacement movement, comprises a first three-phase electric motor (41) and a second three-phase electric motor (42) having a circuit assembly (100) for operating the electric motors (41, 42), characterized in that the circuit assembly (100) comprises a first control path (101) having a first power module (103) for controlling the first electric motor (41) and a second control path (102) having a second power module (104) for controlling the second electric motor (42), and in that the circuit assembly (100) comprises a first computing unit (107) and a first driver stage (105), wherein the first computing unit (107) is designed to determine an electric motor setpoint specification on the basis of acquired parameters and to actuate a power module (103, 104) to influence the motor currents via a driver stage (105, 106), so that the electric motor setpoint specification is implemented.

2. The braking device (1) as claimed in claim 1, characterized in that the second positioning drive (7) is coupled in series with the first positioning drive (6), wherein the first positioning drive (6) has a first drive wheel (65), which is drivable to rotate, and the second positioning drive (7) has a second drive wheel (75), which is drivable to rotate and is coaxial to the first drive wheel (65), wherein a coupling device (8, 9) is arranged between the first drive wheel (65) and the second drive wheel (75), and wherein the coupling device is designed as a friction clutch (8, 9) having a friction element (8), which is connectable in the coupling engagement in a friction-locked manner to a counter friction element (9), wherein the first electric motor (41) enables an operation of the first positioning drive and the second electric motor (42) enables an operation of the second positioning drive.

3. The braking device (1) as claimed in claim 1 or claim 2, characterized in that the circuit assembly (100) is designed to control the first electric motor (41) and the second electric motor (42) using the first computing unit (107) and the first driver stage (105).

4. The braking device (1) as claimed in any one of the preceding claims, characterized in that the circuit assembly (100) furthermore comprises a second driver stage (106), wherein the first driver stage (105) is assigned to the first control path (101) and the second driver stage (106) is assigned to the second control path (102).

5. The braking device (1) as claimed in any one of claims 1 to 3, characterized in that the circuit assembly (100) furthermore comprises a second driver stage (106) and a second computing unit (108), wherein the first driver stage (105) and the first computing unit (107) are assigned to the first control path (101) and the second driver stage (106) and the second computing unit (108) are assigned to the second control path (102).

6. The braking device (1) as claimed in claim 5, characterized in that the first computing unit (107) is designed to actuate the first power module (103) to influence the motor currents of the first electric motor (41) via the first driver stage (105) and the second computing unit (108) is designed to actuate the second power module (104) to influence the motor currents of the second electric motor (42) via the second driver stage (106).

7. The braking device (1) as claimed in any one of claims 4 to 6, characterized in that the first computing unit (107) is designed to actuate the first power module (103) to influence the motor currents of the first electric motor (41) via the first driver stage (105) and to actuate the second power module (104) to influence the motor currents of the second electric motor (42) via the second driver stage (106).

8. The braking device (1) as claimed in any one of the preceding claims, characterized in that a first rotor position sensor (109) is assigned to the first electric motor (41) and a second rotor position sensor (110) is assigned to the second electric motor (42), which are each connected to the first computing unit (107) and / or the second computing unit (108) to transmit rotor position signals.

9. The braking device (1) as claimed in any one of the preceding claims, characterized in that the first control path (101) comprises a first connection element (111) for connection to a voltage source of a motor vehicle as an energy source and / or the second control path (102) comprises a second connection element (112) for connection to a voltage source of a motor vehicle as an energy source.

10. The braking device (1) as claimed in claim 9, characterized in that the first connection element (111) and / or the second connection element (112) comprises an EMI filter (121).

11. The braking device (1) as claimed in any one of the preceding claims, characterized in that the first control path (101) comprises a first interface (113) for connection to a communication channel of a motor vehicle and / or the second control path (102) comprises a second interface (114) for connection to a communication channel of a motor vehicle.

12. The braking device (1) as claimed in any one of the preceding claims, characterized in that the first control path (101) comprises a third interface (115) for connection to a wheel speed sensor and / or the second control path (102) comprises a fourth interface (116) for connection to a wheel speed sensor.

13. The braking device (1) as claimed in any one of the preceding claims, characterized in that the first control path (101) and / or the second control path (102) comprises a transceiver unit (124).