Brake system for motor vehicle

Abstract

The invention relates to a brake system (110) for a motor vehicle, comprising at least two electric brake devices (1) having at least two electric servomotors (41, 42), and comprising at least two voltage sources (P1, P2) which are independent of one another, said voltage sources (P1, P2) being electrically connected to the electric brake devices (1) in order to supply voltage. A first servomotor (41) of the at least two servomotors is assigned to a first voltage source (P1) and a second servomotor (42) of the at least two servomotors is assigned to a second voltage source (P2). In order to achieve a higher degree of operational safety, the invention proposes that each brake device (1) has a brake actuator (4, BM1, BM2, BM3, BM4) which has at least a first servomotor (41) and a second servomotor (42).

Description

Technical Field

[0001] The invention relates to a braking system for a motor vehicle, comprising at least two electric brake devices having at least two electric servomotors, and comprising at least two mutually independent voltage sources, wherein at least one of the servomotors is assigned to a first voltage source for voltage supply and at least one of the servomotors is assigned to a second voltage source. Background Art

[0002] This braking system includes at least two electric brake devices, each of which is assigned to a wheel of the motor vehicle to be braked. The electric brake devices, also known as brake units or wheel brakes, have an electric brake actuator, which is supported on the chassis relative to the rotation of the wheel to be braked and has at least one electric servomotor. This actuator acts on a braking component, such as a brake pad, via the actuator. By driving the actuator motor, the brake pad can be brought into braking engagement with an opposing brake component, such as a brake disc, attached to the wheel to be braked. During braking engagement, frictional contact is generated between the braking component and the opposing brake component, wherein the greater the adjustment force applied by the actuator in the adjustment direction, the greater the braking torque generated by friction.

[0003] The braking system is electrically controlled. The electrical brake command to initiate the braking process can be generated manually by an input device such as a brake pedal or parking brake switch, and additionally or alternatively by an automatic input device such as an anti-lock braking system (ABS) or an automated driving system (ADS). To activate the braking device, the servo motor of the brake actuator is controlled to be energized by a voltage source to cause the brakes to be applied or released.

[0004] To improve operational safety, the prior art document DE 195 37 464 A1 proposes a redundant power supply. This prior art describes a braking system of the type mentioned above, which has four electric brake devices assigned to the wheels to be braked, each of which has an electric servo motor. Redundant operation is made possible by providing two independent voltage sources, such as batteries, a first of which is assigned to supply power to at least one of the servo motors, energizing the servo motor when needed, and at least a second voltage source correspondingly assigned to supply power to at least one other servo motor. For example, the two brake devices assigned to the wheels of the vehicle's front axle can be powered by the first voltage source, while the two brake devices assigned to the rear axle can be powered by the second voltage source. This means that if one of the two voltage sources fails, the brake device assigned to the remaining intact voltage source can continue to be actuated, thereby braking at least the wheels whose brake devices are assigned to the intact voltage source. However, this has the disadvantage that if the power supply fails, only some of the vehicle wheels, for example the two front wheels or the rear wheels, or even the front and rear wheels at a wheel diagonal can be braked. This can impair driving safety and braking safety.

[0005] In view of the above problems, an object of the present invention is to achieve higher operational safety. Summary of the Invention

[0006] According to the invention, this object is achieved by a brake system having the features of claim 1. Advantageous developments can be found in the dependent claims.

[0007] In a braking system for a motor vehicle, comprising at least two electric brake devices having at least two electric servomotors and at least two independent voltage sources, wherein at least one of the servomotors is assigned to a first voltage source for power supply and at least one of the servomotors is assigned to a second voltage source, it is provided according to the invention that at least one brake device in each case has a brake actuator having a first servomotor and a second servomotor.

[0008] With respect to the two voltage sources mentioned hereinafter, the concept includes the first voltage source and the second voltage source together, and thus the first servo motor and the second servo motor are collectively referred to as two servo motors.

[0009] In the present invention, a vehicle wheel to be braked, preferably each vehicle wheel to be braked (also referred to as a wheel for short), can have a brake device, each brake device having a brake actuator with at least two servomotors. The brake actuator can include a first servomotor and a second servomotor, wherein the first servomotor is associated with a first voltage source and can be energized by the first voltage source, and the second servomotor can be energized independently of the first voltage source, or the first servomotor is energized by the second voltage source and the second servomotor is energized by the first voltage source. This significantly differs from the prior art, in which a brake device for a vehicle wheel has only a single servomotor that is assigned to one of the two voltage sources.

[0010] One advantage of the present invention is that the braking device remains functional even if one of the two voltage sources is damaged or fails. In this case, only one of the two servomotors fails, and the other remains fully functional to produce an adequate braking effect. Thus, even if one of the two voltage sources fails and one of the servomotors becomes uncontrollable, each wheel interacting with the braking device according to the present invention remains brakeable. In contrast, in the prior art, the braking device becomes completely inoperable in the event of a failure of the relevant voltage source. The present invention thus allows for a higher level of redundancy, resulting in greater braking and driving safety.

[0011] In a braking system, each braking device assigned to a wheel to be braked can be designed according to the invention and connected to two voltage sources. Thus, all braking devices remain fully functional even in the event of a power source failure, forming a fully redundant system.

[0012] Alternatively, it can be provided that only some of the brake devices in the brake system have two servomotors according to the invention assigned to two voltage sources, while the servomotors of the remaining brake devices are each assigned to only one voltage source. Individual brake devices can be assigned to different voltage sources. This latter design has the advantage of being relatively cost-effective and already allows for an adaptive, sufficient redundancy. This also has the advantage of being able to flexibly adapt the design to the required safety level.

[0013] Preferably, in the braking system according to the present invention, at least two braking devices each have two servomotors. Particularly preferably, each braking device is designed such that, for example, a braking system having four wheels to be braked has a total of at least eight servomotors. As explained above, two servomotors can be assigned to the two voltage sources for each of the braking devices, or only some of the braking devices can be designed according to the present invention.

[0014] Provision can be made for at least one brake actuator to be designed as a front wheel brake actuator, and at least one brake actuator to be designed as a rear wheel brake actuator. Preferably, two front wheel brake actuators can be provided, assigned in pairs to the front axle of the motor vehicle. Correspondingly, two rear wheel brake actuators can be provided, assigned in pairs to the rear axle of the motor vehicle. Preferably, both front wheel brake actuators and, additionally or alternatively, both rear wheel brake actuators can be designed according to the present invention. This allows for flexible adaptation to the desired degree of redundancy.

[0015] Advantageously, the first servomotor of the front wheel brake actuator is connected to a first voltage source, and the second servomotor of the front wheel brake actuator is connected to a second voltage source. Preferably, the two front wheel brake actuators assigned to the front axle can be designed in the manner according to the present invention. This ensures that the braking function of the vehicle's front wheels is fully redundantly protected, with an overall maximum braking effect due to the inertial forces acting on the vehicle during braking.

[0016] The first servomotor of the rear wheel brake actuator can be connected to a first voltage source, and the second servomotor of the rear wheel brake actuator can be connected to a second voltage source. Preferably, the two rear wheel brake actuators associated with the rear axle can be designed in the manner according to the present invention. In particular, if the front wheel brake actuator is designed according to the present invention in accordance with the above-described embodiment, full redundant protection for all wheels to be braked can be achieved. This has the advantage that even if the power supply or individual servomotors fail, all brake systems remain functional.

[0017] Alternatively, provision can be made for the first and second servomotors of the rear wheel brake actuators to be connected to a common voltage source. The fact that the two servomotors of the rear wheel brake actuators are connected in parallel to either the first or second voltage source means that both servomotors can only be energized and thus activated together, but this has the advantage of simplifying control. Due to the overall lower braking effect at the rear wheels, the associated reduced redundancy of the overall braking system can be tolerated, particularly if the front wheel brake system is designed according to the present invention, whereby a large portion of the overall braking effect is already redundantly protected.

[0018] In the last-mentioned embodiment, when two brake devices are assigned to the rear axle, provision can be made for the brake actuator of one brake device to be assigned to a first voltage source and to be energized by this first voltage source, while the brake actuator of the corresponding other brake device is assigned to a second voltage source. This ensures that at least one of the rear wheels can still be braked in the event of a power failure. This achieves greater redundancy than would be achieved if all servomotors of the rear wheel brake actuators were connected in parallel to only one of the voltage sources.

[0019] An advantageous refinement can provide at least a third voltage source. Thus, the braking system can have three or more voltage sources. The term "third or additional voltage source" hereinbelow may refer to any other voltage source in addition to the first and second voltage sources, such as a fourth or nth voltage source. Compared to two voltage sources, the use of a third or additional voltage source can achieve an even higher degree of redundancy. This means that redundancy is maintained even if one voltage source fails, ensuring a sufficient braking effect even in the unlikely event of a failure of another voltage source.

[0020] Provision can be made for the first servomotor of the front wheel brake actuator to be connected to the first or second voltage source, and for the second servomotor of the front wheel brake actuator to be connected to a third voltage source. This means that even if a voltage source fails, at least one of the front wheels can still be braked. This achieves fully redundant protection for the front axle brake system.

[0021] Even in embodiments with three or more voltage sources, it can be advantageous to connect the first servomotor of the front wheel brake actuator to the first voltage source and the second servomotor of the front wheel brake actuator to the second voltage source. This already achieves redundant protection of the front axle brake system.

[0022] Advantageously, the first servomotor of the rear wheel brake actuator is connected to the first voltage source or the second voltage source, and the second servomotor of the rear wheel brake actuator is connected to the third voltage source. Thus, both rear wheel brake actuators remain functional in the event of a failure of the first and / or second voltage source.

[0023] An advantageous embodiment can provide that the first or second servomotor of the rear wheel brake actuator is connected to the third voltage source, and the respective other servomotor of the rear wheel brake actuator is connected to the first or second or further voltage source. Thus, even in the unlikely event that the first and second voltage sources fail and, for example, the front wheel brake actuator supplied by the first and second voltage sources fails completely, the rear wheel brake actuators, preferably both rear wheel brake actuators assigned to the rear axle, remain functional.

[0024] It can also be provided that the first and second servomotors of the rear wheel brake actuators are connected to a common voltage source. The two servomotors of the rear wheel brake actuators can be powered by the first, second, or third voltage source. The parallel connection means that the two servomotors of the rear wheel brake actuators can only be activated together. This has the advantage of simplified control. Due to the overall lower braking effect at the rear wheels, the associated reduction in redundancy of the entire braking system can be tolerated, particularly when the front wheel brake system is designed according to the present invention, thus already preserving a large portion of the overall braking effect redundantly.

[0025] In the latter embodiment, it can be advantageous to provide that, when two brake devices are assigned to one rear axle, the two servomotors of one brake device are assigned to and energized by one voltage source, while the two servomotors of the corresponding other brake device are assigned to another voltage source. This ensures that at least one of the rear wheels can still be braked in the event of a voltage source failure. In this way, greater redundancy can be achieved compared to a situation where all servomotors of the rear wheel brake actuators are connected in parallel to only one of the voltage sources.

[0026] The voltage sources and servomotors can preferably be connected to a central control unit (ECU = Electronic Control Unit). This unit uses a predefined control algorithm to determine the control currents supplied to the servomotors of all brake actuators, which are necessary to generate a defined wheel braking torque. The unit can also preferably monitor the operating status of the servomotors and voltage sources. If one of the voltage sources or servomotors fails, the braking force of the intact voltage source and servomotor can be increased, for example, by enabling them accordingly. For example, if a voltage source fails, the servomotor connected to the still intact voltage source can be controlled with a higher current to compensate for the braking force of the failed servomotor.

[0027] The optimal braking torque, which can be used to achieve the shortest possible braking distance, preferably without locking the wheels, can be determined based on the target value for the braking command and other actual parameters relevant to the braking process, such as wheel position, wheel speed, servo motor current, braking force, vehicle speed, etc. In the prior art mentioned above, it is known to feed at least the value for the braking command and possibly other values ​​to a central control unit (ECU). The braking system can have at least two wheel brake control units separate from the ECU. These wheel brake control units can be electrically controlled by the central control unit using control signals.

[0028] The fact that at least two wheel brake control units are provided, each of which is assigned to a braking device and connected to a brake actuator, means in other words that the at least two braking devices each have their own wheel brake control unit, which is connected to the central control unit and to the brake actuator.

[0029] Each wheel brake control unit can be controlled by an ECU using a target brake value generated by a brake command received from an input device. By combining a central control unit according to the present invention with at least two decentralized wheel brake control units assigned to the wheels, decentralized brake control is achieved. This enables, for example, simpler and shorter wiring of wheel sensors, such as wheel position sensors, which are assigned to the wheels and can be directly connected to the wheel brake control units of the brake devices also assigned to the wheels. This can advantageously reduce manufacturing and assembly costs. Furthermore, sensitivity to external interference can be reduced. The decentralized design of the brake control units according to the present invention also allows for greater redundancy, so that operational reliability can be improved.

[0030] The wheel brake control unit can preferably be integrated with the brake device. This allows a compact, safe and easy-to-install design.

[0031] Preferably, each of the braking devices has a wheel brake control unit; for example, in a four-wheel vehicle having four braking devices, corresponding four wheel brake control units can be set, or in a two-wheel vehicle having two braking devices, corresponding two wheel brake control units can be set.

[0032] Preferably, the wheel brake control units are in each case connected to at least one brake actuator. The wheel brake control units control the brake actuators via defined target control signals in order to generate defined braking torques for the wheels assigned to the respective brake device.

[0033] Each wheel brake control unit may be connected to an electric servo motor. The wheel brake control unit may control the servo motor by controlling an electric power target control value of the current. Two or more servo motors of the braking device may also be connected to the wheel brake control unit.

[0034] Preferably, it can be provided that each wheel brake control unit is connected to a sensor device. The sensor device can preferably include wheel sensors assigned to the corresponding wheels to be braked. The wheel sensors can be designed to detect parameters (actual values) relevant to the braking process, such as wheel position, wheel speed, vehicle speed, slip, etc., and forward these parameters to the wheel brake control unit. In addition, the sensor device can be configured to detect the current of the servomotor, the braking force, etc. Preferably, each of the brake devices has a sensor device, preferably at least one wheel sensor. One advantage is that the sensor units, in particular the wheel sensors assigned to the corresponding brake units, can be connected with less effort. The fact that the relevant parameters can be measured on the wheels to be braked and fed directly to the wheel brake control unit without the need for interconnection with a central control unit can increase operational reliability and redundancy.

[0035] It may be provided that each wheel brake control unit has a control unit. The power control unit compares an actual value of a wheel sensor or another sensor device with a target value of a braking command transmitted from the central control unit to the wheel brake control unit and controls the servomotor or servomotors of the brake actuator accordingly in order to achieve the target value.

[0036] In a braking device for a motor vehicle, which comprises a brake actuator with an electric servomotor and wheel sensors, provision can be made for the braking device to have a wheel brake control unit which can be connected to the brake actuator and the wheel sensors.

[0037] The brake device can preferably be used in a brake system of the type described above, wherein all of the features described herein can be implemented.

[0038] The wheel sensors, also called wheel position sensors, can be designed as described above.

[0039] The wheel brake control unit is designed for connection to the central control unit and to the at least one wheel sensor.The at least one servomotor of the brake actuator can be electrically controlled by the wheel brake control unit.

[0040] The wheel brake control unit can preferably be integrated with the brake device, for example by structural integration in a housing of the brake device.

[0041] In a method for controlling a braking system of a motor vehicle, the motor vehicle has at least two braking devices, each of which has a brake actuator, wherein each of the brake actuators has an electric servomotor, and wherein the braking devices are connected to a central control unit, which is designed to be connected to at least one input device, wherein a braking command is input into the central control unit by the at least one input device, and the central control unit controls the brake actuators using control signals. It can be provided that the central control unit sends a control signal to at least two wheel brake control units respectively assigned to the braking devices, each wheel brake control unit controlling the brake actuator of the corresponding braking device.

[0042] All features and procedures described above can be used to implement the method in combination with the braking system and the braking device.

[0043] One advantage of this approach is that the decentralized control architecture can achieve improved operational reliability, for example, due to its robust design, it is less sensitive to external disturbances. Furthermore, the decentralized control architecture enables the redundant allocation of control functions between the central control unit and the wheel brake control units, as described herein. For example, anti-lock brake control (ABS) can be performed by the wheel brake control units together with the associated wheel sensors in a decentralized manner and independently of the central control unit. This results in greater operational safety.

[0044] Advantageously, actual signals from the wheel sensors of the respective braking devices are transmitted to each of the wheel brake control units. Based on a control algorithm, the actual signals from the wheel sensors, such as wheel position and / or wheel speed, are taken into account to adjust the control of the corresponding brake actuator in the corresponding wheel brake control unit to achieve the target value specified by the braking command. The wheel sensors preferably provide actual signals of the measured parameters in real time. Actual values ​​provided by other sensor devices, such as servo motor current, braking force, vehicle speed, etc., may also be considered and processed.

[0045] The method according to the present invention has the advantage that the signals provided by the wheel sensors (wheel position sensors) can be processed almost in real time in the decentralized wheel brake control units of the braking system. This allows for increased processing speed and operational reliability, as well as a redundant design of the control system.

[0046] According to an advantageous embodiment of the braking system according to the invention, it can be provided that the braking device comprises an actuating device and a braking component connected to the actuating device, which braking component can be adjusted along an axis by the actuating device and can be brakingly engaged with a counter-braking component, wherein the actuating device has a first actuating drive and a second actuating drive connected in series with the first actuating drive, wherein the first actuating drive has a first rotatably driven drive wheel and the second actuating drive has a rotatably driven second drive wheel coaxial with the first drive wheel, wherein a coupling device is arranged between the first drive wheel and the second drive wheel.

[0047] The actuating device can be driven by at least one electric servomotor. The electric servomotor is preferably geared to at least one drive wheel. Preferably, a servomotor can be provided for each of the first and second drive wheels. According to the present invention, one or more servomotors can be controlled by a wheel brake control unit associated with the braking device.

[0048] In the latter embodiment, it can be provided that the coupling device is designed as a friction coupling having a friction element which can be frictionally connected to a counter-friction element in coupling engagement.

[0049] Hereinafter, the first drive wheel and the second drive wheel are also collectively referred to as two drive wheels or simply drive wheels.

[0050] The drive wheels can each be designed as a gear, for example as a spur gear, or as a belt or a toothed belt pulley or worm gear, so that overall a transmission wheel is provided via which the drive torque from the electric servomotor can be coupled into the actuating drive.

[0051] A friction coupling is implemented between the drive wheels. The friction coupling comprises a friction element connected to one of the drive wheels in a torque-locked manner, and a corresponding counter-friction element connected to the other drive wheel in a torque-locked manner. The friction element can be frictionally coupled with the counter-friction element in any relative angular position. Compared to a form-fit connection, this results in a purely frictional coupling. Thus, compared to the discrete engagement stages of a pawl connection, the relative position of the drive wheels to one another can be continuously specified. Consequently, the second actuating drive can be adjusted uniformly and continuously relative to the first actuating drive, and the air gap can be continuously adjusted. This is particularly advantageous with respect to the continuous wear of the brake components, i.e., the continuous wear of the brake pads, during operation, in terms of uniform tracking of the optimal operating point of the braking device. Compared to a step-by-step adjustment option, a continuously improved response behavior of the braking device can be achieved, thereby achieving increased operating safety and better operating comfort.

[0052] Another advantage over a pawl coupling is that essentially no axial relative movement is required between the coupling elements engaged in the coupling, such as the drive wheel or the pawl element—these coupling elements must be able to move relative to each other to produce and release a releasable form fit—to actuate and release the coupling device. In contrast, a purely frictional connection between the friction element and the counter-friction element according to the present invention can be established solely by the applied axial actuation force, without the friction element and the counter-friction element having to move axially relative to each other. This makes the design of the coupling device simpler and more reliable.

[0053] The friction coupling preferably has a defined, predeterminable coupling torque. The coupling torque specifies the maximum differential torque that can be transmitted by the friction connection in the coupling engagement between the friction element and the counter-friction element. If 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 present invention slides continuously, allowing for improved and uniform readjustment of the air gap. Furthermore, the design does not need to account for and absorb axial deflection movements of the pawl element, as is the case with known pawl couplings.

[0054] Advantageously, the friction element and the counter-friction element are coaxially arranged. This coaxial arrangement corresponds to the coaxial arrangement of the drive wheel. The friction element and the counter-friction element can be arranged in the region of the axially opposite end faces of the drive wheel in a simple and compact design. As described above, the creation of a purely frictional connection in the coupling means that no moving parts are required.

[0055] In an advantageous embodiment, the friction element and the counter-friction element may be conical. The friction element may have a conical section with a conical friction surface that converges at least in sections in the adjusted axial direction. This conical section may be designed as an outer or inner cone and connected to a corresponding conical section on the counter-friction element, which is designed as an inner or outer cone in the opposite direction 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 actuation force of the coupling. One advantage of this is that the cone can be used to convert the axial actuation force of the coupling into a normal force acting between the frictionally contacting conical friction surfaces. In this way, a relatively small axial actuation force can be converted into a larger normal force in the friction contact due to the flatter pitch, thereby achieving a high coupling torque with a relatively small axial actuation force of the coupling.

[0056] As an alternative or in addition to the above-described embodiments, the friction elements and counter-friction elements can be planar. In this case, the corresponding friction surfaces are designed at least in sections as planar axial surfaces, similar to a disc coupling. This enables a space-saving arrangement, especially when only relatively low coupling torques are to be achieved.

[0057] It can preferably be provided 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 surface and the counter-friction surface are pressed against each other in the friction connection with a predetermined axial preload force. In order to generate the preload force, an elastic preload element, such as a spring element or the like, can preferably be provided. The coupling torque of the friction coupling is determined by the actuating force acting perpendicularly to the friction contact, i.e. the force applied axially between the friction element and the counter-friction element, wherein the greater the preload force, the greater the coupling torque. This opens up the advantageous possibility of specifying the coupling torque solely by the preload force applied by the preload 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 preload force can be specified and adjusted solely by the spring constant and the compression of the spring.

[0058] The above embodiment can be advantageously implemented because the friction element and / or counter-friction element can be axially displaced and supported against the first or second drive wheel via an axially effective spring element. The friction element or counter-friction element is connected to one drive wheel in a torque-locked and axially displaceable manner, for example, via a radially protruding drive that creates a positive fit effective in the circumferential direction. A spring element, preferably designed as an axially effective compression spring, axially clamped between the friction element or counter-friction element and one drive wheel ensures that the friction element or counter-friction element is axially prestressed against a corresponding counter-friction element or friction element axially supported on the other drive wheel, i.e., axially pressed against each other in frictional contact. The corresponding counter-friction element or friction element is connected to the other drive wheel in a rotationally engaged manner. Alternatively or additionally, the counter-friction element can also be supported on one of the drive wheels via the spring element. One advantage of this arrangement is that the friction coupling can be combined between the drive wheels in a simple and space-saving manner.

[0059] In an advantageous refinement, the friction element and / or counter-friction element can be arranged in the first drive wheel or the second drive wheel. For example, one drive wheel can be designed in a substantially drum-like shape, so that the friction element or counter-friction element can be arranged in the interior space enclosed by the rotating gear or gear rim. This allows for a compact design that is protected from external influences. For example, the drive wheel of the first actuating drive can have a conical friction element that axially engages in a counter-friction element designed as an inner cone, which is arranged at least partially inside the second drive wheel.

[0060] By arranging the drive wheel within the axial extension of the actuating drive, ie the drive wheel does not protrude axially on one side, a particularly compact design can be achieved, in particular in the last-mentioned embodiment.

[0061] Preferably, the friction element and / or the counter-friction element have a friction lining. The friction element and the counter-friction element preferably have a metal body, for example made of steel. To avoid metal-to-metal contact, a coating or lining may be preferably applied to create a friction pair with defined friction forces, for example, a coating or lining made of sintered metal and / or ceramic friction material, a composite material, etc. This ensures a defined, repeatable coupling torque.

[0062] It may be provided that the actuating drive comprises a spindle drive. In this case, a threaded spindle engages in a spindle nut in a known manner and is driven in relative rotation via a drive wheel connected to the threaded spindle or spindle nut. The spindle nut can form the drive element on the input side of the actuating drive, and the threaded spindle can form the output element on the output side, which can be linearly adjusted relative to the drive element, or vice versa.

[0063] The actuating drive can have a ball ramp arrangement, a wedge disk arrangement, or a rocker pin arrangement. In a ball ramp arrangement, also known as a ramp bearing, the drive element and the output element preferably have cam disks with raceways or ramps inclined relative to the axis, between which balls are arranged to roll in the circumferential direction. Since the balls roll on the ramps, relative rotation causes the output element to shift axially relative to the drive element. In known rocker pin arrangements, a rocker pin is arranged between the drive element and the output element, and each rocker pin is supported circumferentially. During relative rotation, the rocker pin tilts more or less toward the axis, depending on the direction of rotation. This allows the distance between the drive element and the output element to be adjusted.

[0064] In an actuating device, two actuating drives that function in the same manner can be combined to form a first actuating drive and a second actuating drive, for example, to form two spindle drives. It is also possible to combine two different designs for adjusting the air gap, for example, a ball ramp arrangement as the first actuating drive and a spindle drive as the second actuating drive. The respective characteristic properties of each design can be optimally utilized. For example, a ball ramp arrangement can be used to achieve nonlinear adjustment characteristics with minimal effort and / or at least partially achieve self-locking characteristics and / or achieve a defined dead point or extended position, which enables a defined adjustment stroke. Achieving these positive characteristics may, at least in part, require precise specifications for the air gap, which can be easily achieved with the friction coupling according to the present invention.

[0065] The braking device according to the present invention may comprise an actuating device and a braking component connected to the actuating device, which braking component can be adjusted along an axis by the actuating device and can be brakingly engaged with a counter-braking component, wherein the actuating device comprises a first actuating drive and a second actuating drive connected in series with the first actuating drive, wherein the first actuating drive comprises a first rotatably driven drive wheel, and the second actuating drive comprises a second rotatably driven drive wheel coaxial with the first drive wheel, wherein a coupling device is arranged between the first drive wheel and the second drive wheel.

[0066] The actuating device can be driven by at least one electric servomotor. The electric servomotor is preferably geared to at least one drive wheel. Preferably, a servomotor can be provided for each of the first and second drive wheels. According to the present invention, one or more servomotors can be controlled by a wheel brake control unit associated with the braking device.

[0067] In the last-mentioned embodiment of the braking device, it can preferably be provided that the coupling device is designed as a friction coupling having a friction element which can be frictionally connected to a counter-friction element in the coupling engagement.

[0068] Therefore, the advantages described above in conjunction with the brake system can be achieved.

[0069] In order to implement the method, it can be provided that the braking device has an actuating device that can be coupled to the servo motor, the actuating device includes a first actuating drive and a second actuating drive coupled in series with the first actuating drive, and the actuating device acts on a braking component that can be brakingly engaged with a counter-braking component in the axial direction, wherein the first actuating drive has a first drive wheel that can be rotatably driven and a first driving torque can be applied to the first drive wheel for actuation, and the second actuating drive has a second drive wheel that can be rotatably driven and is coaxial with the first drive wheel and a second driving torque can be applied to the second drive wheel. The second drive wheel is actuated, wherein a coupling device is arranged between the first drive wheel and the second drive wheel, wherein, according to the invention, it is provided that the coupling device is designed as a friction coupling and has a predeterminable coupling torque, and over the coupling device, the first drive wheel slides in a sliding manner relative to the second drive wheel, wherein the first drive wheel and the second drive wheel are driven synchronously to actuate the first actuating drive, so that the second actuating drive remains unactuated, and the second drive wheel is driven to actuate the second actuating drive, and the first drive wheel is stationary relative to it, so that the friction coupling slips and the first actuating drive remains unactuated.

[0070] The features mentioned above in connection with the braking device according to the invention can be used individually and in combination to implement the method.

[0071] For adjusting the first actuating drive, the actuating torque can be coupled into the first drive wheel by means of a first electric servomotor, and the second actuating drive can be correspondingly driven by a second electric servomotor.

[0072] In normal braking mode, the first and second drive wheels rotate synchronously. This can be achieved by driving the first and second drive wheels with synchronized drive torques via the first and second servomotors. Alternatively, as long as the transmitted drive torque remains below the coupling torque, the second drive wheel can be driven synchronously with the first drive wheel via the coupling device. In this operating mode, the second actuator remains deactivated and rotates freely as a whole with the brake element.

[0073] During this process, the coupling device can continuously and smoothly slip to adjust the air gap when the coupling torque is exceeded. This can be achieved, for example, by locking the drive wheel of the first actuator, for example, via a brake or corresponding control of the first drive motor, while the second drive motor simultaneously applies a second drive torque, greater than the coupling torque, to the second drive wheel. Consequently, the second drive wheel rotates relative to the first, and by actuating the second actuator, the air gap can be continuously and sensitively adjusted, optimally compensating for the progressive wear of the brake element or brake pad.

[0074] The first and second drive wheels can be coupled in a torque-locked manner via a friction coupling to produce synchronous drive. In this case, the two drive wheels do not need to be driven synchronously by servo motors. Any torque differences can be compensated within a predetermined tolerance range.

[0075] Advantageously, a higher coupling torque can be specified when the first actuating drive is actuated than when the second actuating drive is actuated. The first actuating drive is actuated by synchronously driving the first and second drive wheels. The friction element and the counter-friction element are preloaded against each other by the spring force of the spring element, and the adjustment force of the first actuating drive also 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 is active, resulting in a lower coupling torque. This makes it easier to adjust the air gap. BRIEF DESCRIPTION OF THE DRAWINGS

[0076] Advantageous embodiments of the present invention are explained in more detail below with reference to the accompanying drawings, which specifically show:

[0077] Figure 1 Schematic cross-sectional view of a braking system for a motor vehicle according to the invention,

[0078] Figure 2a According to the structural diagram of the braking system in the first embodiment of the present invention,

[0079] Figure 2b according to Figure 2a The electrical connection diagram of the brake system,

[0080] Figure 2c According to the structural diagram of the braking system in the second embodiment of the present invention,

[0081] Figure 3 A schematic perspective view of a braking device according to the present invention,

[0082] Figure 4 according to Figure 3 A side view of the braking device,

[0083] Figure 5 Through the basis Figure 3 The cross section of the brake device is QQ,

[0084] Figure 6 like Figure 1 A schematic perspective view of a first actuating drive of the braking device is shown,

[0085] Figure 7 From Figure 5 An enlarged detailed view of the actuating device. DETAILED DESCRIPTION

[0086] In the individual figures, identical components are always provided with the same reference symbols and are therefore generally named or mentioned only once in each case.

[0087] Figure 1 Shown is a schematic perspective partial view of a chassis 100 of a motor vehicle.The chassis 100 comprises a steerable wheel (vehicle wheel) 101 which is mounted on a pivotable steering knuckle 103 on a frame portion of a body 102 of the motor vehicle.

[0088] Figure 1 The two wheels 101 shown in FIG. 1 are two front wheels 101V of the front axle of the vehicle.

[0089] The steering system includes a steering shaft 104, at the rear end of which is attached a steering wheel 105 as a manual steering input in the direction of travel. The steering shaft 104 is connected to a steering gear 106, which is connected to a steering knuckle 103 via a tie rod 107 to generate a steering angle.

[0090] Braking system 110 includes a braking device 1 for each of two wheels (vehicle wheels) 101. Braking device 1 for one front wheel 101V is designated BU1, and braking device 1 for the other front wheel 101V is designated BU2. Each of these braking devices includes a brake caliper 2 mounted and supported on vehicle body 102. A brake disc 3, clamped by brake caliper 2, which is fixed relative to the disc, is attached to wheel 101 for co-rotation. Braking devices BU1 and BU2 have identical designs.

[0091] Braking devices 1, ie BU1 and BU2, are connected to a central control unit 112 (ECU) via electrical control lines 111. ECU 112 is also connected to a brake pedal 113, which is shown schematically and attached to vehicle body 102 and represents a manual input device.

[0092] In addition, the ECU 112 may be connected to an automatic input device 114 , which may provide an external control signal to the ECU 112 to control the braking system 110 .

[0093] The braking system comprises a first voltage source P1 and a second voltage source P2, which may be in the form of batteries or accumulators. Both voltage sources P1 and P2 are connected to two braking units BU1 and BU2.

[0094] Figure 2aShown is a schematic diagram of a chassis 100 with a brake system 110. The vehicle has four wheels 101, each of which is assigned a brake device 1 according to the invention.

[0095] Among the total four wheels 101 of the vehicle, two wheels have front wheels 101V of the front axle of the vehicle, and two wheels have rear wheels 101H of the rear axle of the vehicle.

[0096] A total of four brake devices 1 are provided, of which brake devices BU1 and BU2 are assigned to the two front wheels 101V, and two brake devices BU3 and BU4 are assigned to the two rear wheels 101H.

[0097] Each of the braking units BU1 , BU2 , BU3 and BU4 has a respective brake actuator 4 , which is designated as BM1 , BM2 , BM3 and BM4 according to the allocation.

[0098] Each of the braking units BU1, BU2, BU3, and BU4 may also optionally include a wheel brake control unit 120, designated BC1, BC2, BC3, and BC4, respectively. A wheel sensor 121 (S1, S2, S3, S4) may be connected to each wheel brake control unit 120 and is preferably designed as a wheel position sensor that transmits the actual value of the rotational position to the wheel brake control unit 120 in real time during driving.

[0099] The wheel brake control unit 120 may preferably be integrated with the brake device 1 and electrically connected to the brake actuator 4 .

[0100] According to the invention, each of the brake actuators BM1, BM2, BM3 and BM4 has two electric servomotors 41, 42, specifically a first servomotor 41 and a second servomotor 42. According to the invention, these electric servomotors are assigned to voltage sources P1 and P2 and can be energized by these voltage sources P1 and P2.

[0101] Figure 2bAn example of an electrical diagram for assigning the first servomotor 41 and the second servomotor 42 of four brake actuators BM1, BM2, BM3, and BM4 to voltage sources P1 and P2 according to the present invention is shown. For each brake actuator BM1, BM2, BM3, and BM4, the first servomotor 41 is assigned to the first voltage source P1, and the second servomotor 41 is assigned to the second voltage source P2. In this way, a fully redundant arrangement is created that continues to ensure braking of each wheel 101 in the event of a failure in one of the voltage sources P1 or P2. This arrangement can be schematically summarized as follows, where the arrows indicate the connection of the servomotors 41 and 42 to one of the voltage sources P1, P2, and P3:

[0102] BM1 41→P1 42→P2 BM2 41→P1 42→P2 BM3 41→P1 42→P2 BM4 41→P1 42→P2

[0103] Figure 2c As Figure 2a The illustrated view shows a further embodiment of a braking system 101 according to the invention. The braking system 101 has a further third voltage source P3.

[0104] exist Figure 2c In the arrangement shown, the two brake actuators BM1 and BM2 of the front wheel 101V are respectively Figure 2a and Figure 2b As shown, the two rear brake actuators BM3 and BM4 are connected to two voltage sources P1 and P2. The two first servomotors 41 of the two rear brake actuators BM3 and BM4 are connected to and can be energized by a third voltage source P3. The second servomotor 42 of the brake actuator BM3 is connected to the first voltage source P1, and the second servomotor 42 of the brake actuator BM4 is connected to the second voltage source P1. Thus, the two rear wheels remain brakeable even in the unlikely event that both voltage sources P1 and P2 fail simultaneously. If the third voltage source P3 fails, all four wheels 101 can still be braked.

[0105] Schematically, this arrangement can be represented as follows:

[0106]

[0107]

[0108] As Figure 2a 、 Figure 2b and Figure 2cAs an alternative to the examples shown, all combinations of the servo motors 41 and 42 of the brake actuators BM1, BM2, BM3, and BM4 mentioned in the description can also be implemented, which are not explicitly shown in the figures. For example, two servo motors 41 and 42 of a brake actuator BM1, BM2, BM3, or BM4 can be connected in parallel and assigned to one of the voltage sources P1, P2, or P3, while two servo motors 41 and 42 of another brake actuator BM1, BM2, BM3, or BM4 can be assigned to two of the voltage sources P1, P2, or P3.

[0109] For example, the following schematically illustrated arrangement can be implemented:

[0110] BM1 41→P1 42→P2 BM2 41→P1 42→P2 BM3 41→P1 42→P1 BM4 41→P2 42→P2

[0111] or

[0112] BM1 41→P1 42→P2 BM2 41→P1 42→P2 BM3 41→P1 42→P1 BM4 41→P3 42→P3

[0113] or

[0114]

[0115]

[0116] Other combinations not explicitly shown here are conceivable and possible.

[0117] It is also conceivable and possible to provide at least one additional voltage source.

[0118] Each of the four brake devices 1 shown in this example has its own wheel brake control unit 120, which can exchange electrical control signals with wheel sensors 121 and ECU 112 and, based thereon, can control brake actuator 4. Servomotors 41 and 42 can be energized by the corresponding wheel brake control unit 120 to produce a predetermined braking effect.

[0119] Below Figure 3 、 Figure 4 and Figure 5 One embodiment of the brake actuator 4 is shown in detail in FIG. Figure 5 As can be seen in FIG. 4 , the brake actuator 4 has a housing 45 in which a wheel brake control unit 120 is arranged. The brake actuator 4 has circuits connected to the servomotors 41, 42 and the ECU 112. Thus, the wheel brake control unit 120 is integrated with the brake device 1.

[0120] For the sake of Figure 4 and Figure 5In connection with a wheel sensor 121 schematically indicated in FIG, the brake actuator 4 has a connection device 46 , for example an electrical plug connection or the like, which is arranged on a housing 45 .

[0121] Figure 3 An exemplary embodiment of a brake device 1 according to the invention, designed as a disc brake, is shown in its entirety. The brake device 1 comprises a brake disc 2 , which forms a counter-braking element and is connected to a vehicle wheel 101 , not shown here, which is rotatable about a wheel axis R. Brake calipers 3 clamp the two axial end faces of the brake disc 2 .

[0122] The brake disc 2 is designed here as a non-ventilated brake disc made of a solid material. Alternatively, the brake disc 2 can also be designed as an internally ventilated brake disc.

[0123] An electric brake actuator 4 according to the present invention is attached to the brake caliper 3 .

[0124] The brake actuator 4 comprises an actuating device 5 extending axially in the direction of an axis A, which is parallel to the wheel axis R and indicates an adjustment direction V of the actuating device 5 .

[0125] Figure 4 A view of the brake caliper 3 as seen from the brake disc 2 is shown.

[0126] As in Figure 5 As can be seen in the cross-section along the axis A, the brake disc 2 is arranged axially 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 a brake component in the sense of the present invention, is attached to the actuating device 5 and can be adjusted by the actuating device 5 in the axial adjustment direction V given by the axis A to produce on the brake disc 2 the following Figure 5 The braking action is indicated by the arrow in the figure.

[0127] When the brake device 1 is not actuated, there is an axial air gap L between the brake disc 2 and the adjustable brake pad 32, and Figure 4 The axial air gap L is schematically shown in FIG. 1 with an enlarged width.

[0128] The structure of the actuator 5 is Figure 5 Shown in and Figure 7 An enlarged section thereof is shown in FIG.

[0129] The actuating device 5 comprises a first actuating drive 6 having a ramp bearing and a second actuating drive 7 coupled in series axially (with respect to the axis A) to the first actuating drive 6 and having a spindle drive.

[0130] The first actuating drive 6, which is designed as a ramp bearing in the example shown, comprises a cam disc 61 on the drive side and a cam disc 62 on the output side, which are axially and non-rotatably supported on the brake actuator 4. A ball 63 is arranged between the cam disc 61 and the cam disc 62. Figure 6 As can be seen in the schematic view of FIG, the cam discs 61 and 62 have axially opposite ramp-shaped raceways 64 at an angle to the axis A, between which the balls 63 can roll. The output side cam disc 62 is positioned relative to the fixed drive side cam disc 61. Figure 6 The rotation at the top of the output cam disc 62 , as schematically indicated by the curved arrow, results in a linear adjustment of the output cam disc 62 in an adjustment direction V parallel to the axis A. Figure 4 As shown, the brake pad 32 can be brought into a braking engagement state by actuating the first actuating drive 6 .

[0131] The cam disc 62 is connected to a coaxial gear 65 which is designed as a spur gear and forms a drive gear in the sense of the present invention.

[0132] The gear wheel 65 is in gear engagement with the first electric servomotor 41 , which effects the rotational drive of the cam disc 62 and thus the actuation of the first actuating drive 6 .

[0133] The second actuating drive 7, which is designed as a spindle drive in the example shown, has a threaded spindle 71 on the output side, which engages in an internal thread of a drive-side spindle nut 72. 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 drive-side spindle nut 72 are combined in one component.

[0134] The threaded spindle 71 is connected via a hub portion 74 to a coaxial gear 75 which is mounted in an axially fixed and rotatable manner in the brake actuator 4. The threaded spindle is coupled to the gear 75 in a torque-locked but axially displaceable manner via a driver 73 which can, for example, have radially projecting projections or teeth which engage in an axially displaceable manner in an axial groove of the hub portion 74.

[0135] Like the gear 65, the gear 75 can be designed as a spur gear and is arranged coaxially adjacent to the gear 65. The gear 75 is in gear engagement with the second electric servomotor 42, which enables the threaded spindle 71 to be driven in rotation and thus enables the second actuating drive 7 to be actuated.

[0136] The threaded spindle 71 is axially connected via a thrust bearing 43, for example an axial rolling bearing as shown, to a thrust piece 44 to which a displaceable brake pad 32 is attached, as can be seen in FIG. Figure 4 Thrust member 44 may also be referred to as a piston.

[0137] The coupling device according to the invention has a friction element 8, which is indicated as a coaxial conical projection from the cam disc 62 toward the second actuating drive 7. This conical projection has a conical friction surface 81 arranged outside the outer cone. The friction element 81 can preferably be formed in one piece with the cam disc 62 / spindle nut 72.

[0138] The friction element 8 is frictionally coupled in coupling engagement with the counter friction element 9. The conical protrusion is axially inserted into a corresponding conical opening of the counter friction element 9, which has a conical friction surface 91 arranged in an inner cone. In coupling engagement, the friction surface 81 and the counter friction surface 91 are in frictional contact with each other, as in Figure 7 It can be clearly seen in.

[0139] The counter-friction element 9 is coupled in a torque-locked but axially displaceable manner to the gear wheel 75 via a driver 92 which engages in an axially displaceable manner in a corresponding groove 76 in the hub part 74 or the gear wheel 75 .

[0140] A 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. The axially effective spring force of the spring element 93 elastically supports the counter-friction element 9 against the friction element 8. This results in a defined coupling torque of the friction coupling formed by the friction element 8 and the counter-friction element 9 according to the invention.

[0141] To actuate the brake device 1, gears 65 and 75 rotate synchronously, causing the first actuating drive 6 to perform a working stroke in the adjustment direction V, causing the brake pad 32 to pass through the air gap L and engage the brake disc 2 in a braking manner. The synchronous driving of gears 65 and 75 can be achieved by synchronizing the drive speeds of the servomotors 41 and 42, or by driving only one of the servomotors 41 or 42 while the other servomotor 42 or 41 is running idle. In this case, the frictional coupling engagement between the friction element 8 and the counter-friction element 9 ensures the synchronous rotation of gears 65 and 75.

[0142] To adjust the width of air gap L, gear 65 is fixed or blocked, for example, by corresponding actuation of first servomotor 41. Second servomotor 42 rotates gear 75 relative to gear 65, with the friction coupling continuously sliding. Consequently, second actuating drive 7 is uniformly adjusted, allowing the width of air gap L to be continuously adjusted and adapted, for example, to compensate for wear of brake pads 32.

[0143] The fact that the friction element 8 and the counter-friction element 9 are arranged completely or at least partially within the gear wheels 65 and 75 means that a particularly compact design can be achieved.

[0144] Figures 3 to 7 The brake device shown in FIG is designed as a floating caliper brake, also known as a sliding caliper. The brake pad 32 is pressed against the brake disc 2 by a thrust piece 44, and the brake pad 31 is pressed against the brake disc 2 by a brake caliper 3, which can be displaced relative to the brake disc 2 in the direction of the axis A. Alternatively, the solution according to the invention can also be used with a fixed caliper brake.

[0145] Reference numerals

[0146] 1. BU1, BU2, BU3, BU4 brake units

[0147] 100 chassis

[0148] 101 Wheel (vehicle wheel)

[0149] 101V front wheel

[0150] 101H rear wheel

[0151] 102 Body

[0152] 103 Steering knuckle

[0153] 104 steering shaft

[0154] 105 Steering Wheel

[0155] 106 Steering gear

[0156] 107 tie rod

[0157] 110 Braking System

[0158] 111 Control Line

[0159] 112 Central Control Unit (ECU)

[0160] 113 brake pedal

[0161] 114 Input Device

[0162] 120 Wheel brake control unit

[0163] (BC1, BC2, BC3, BC4)

[0164] 121 wheel sensor

[0165] 2 brake discs

[0166] 3 brake calipers

[0167] 31, 32 brake pads

[0168] 4. BM1, BM2, BM3, BM4 brake actuators

[0169] 41, 42 servo motor

[0170] 43 thrust bearing

[0171] 44 thrust piece

[0172] 45 shell

[0173] 46 Connecting device

[0174] 5 Actuator

[0175] 6. First Actuator

[0176] 61 Cam plate

[0177] 62 cam plate (integrated with the spindle nut 72)

[0178] 63 Ball

[0179] 64 Rollerway

[0180] 65 Gear

[0181] 7 Second actuator

[0182] 71 threaded spindle

[0183] 72 spindle nut (integrated with cam disc 62)

[0184] 73 Driver

[0185] 74 hub part

[0186] 75 Gear

[0187] 76 slots

[0188] 8 Friction element

[0189] 81 friction surface

[0190] 9 Reverse friction element

[0191] 91 Opposing friction surface

[0192] 92 Driver

[0193] 93 Spring element

[0194] A Axle

[0195] R wheel axle

[0196] V adjustment direction

[0197] L Air gap

[0198] P1, P2, P3 voltage sources

Claims

1. A braking system (110) for a motor vehicle, the braking system (110) comprising at least two electric braking devices (1), the electric braking devices (1) having at least two electric servomotors (41, 42), and the braking system (110) comprising at least two mutually independent voltage sources (P1, P2), wherein: At least one of the servo motors (41, 42) is assigned to a first voltage source (P1) for voltage supply, and at least one of the servo motors (41, 42) is assigned to a second voltage source (P2), It is characterized by The brake device (1) has in each case a brake actuator (4, BM1, BM2, BM3, BM4), which has at least a first servomotor (41) and a second servomotor (42).

2. The braking system according to claim 1, characterized in that At least one brake actuator (4, BM1, BM2, BM3, BM4) is designed as a front wheel brake actuator (BM1, BM2), and at least one brake actuator (4, BM1, BM2, BM3, BM4) is designed as a rear wheel brake actuator (BM3, BM4).

3. The braking system according to claim 2, characterized in that: The first servomotor (41) of the front wheel brake actuator (BM1, BM2) is connected to the first voltage source (P1), and the second servomotor (42) of the front wheel brake actuator (BM1, BM2) is connected to the second voltage source (P2).

4. Braking system according to one of the preceding claims 2 or 3, characterized in that The first servomotor (41) of the rear wheel brake actuator (BM3, BM4) is connected to the first voltage source (P1), and the second servomotor (42) of the rear wheel brake actuator (BM3, BM4) is connected to the second voltage source (P2).

5. Braking system according to one of the preceding claims 2 or 3, characterized in that The first servomotor (41) and the second servomotor (42) of the rear wheel brake actuator (BM3, BM4) are connected to a common voltage source (P1, P2).

6. Braking system according to one of the preceding claims, characterized in that At least one third voltage source (P3) is provided.

7. The braking system according to claim 6, characterized in that The first servomotor (41) of the front wheel brake actuator (BM1, BM2) is connected to the first voltage source (P1) or the second voltage source (P2), and the second servomotor (42) of the front wheel brake actuator (BM1, BM2) is connected to the third voltage source (P3).

8. The braking system according to claim 6, characterized in that The first servomotor (41) of the front wheel brake actuator (BM1, BM2) is connected to the first voltage source (P1), and the second servomotor (42) of the front wheel brake actuator (BM1, BM2) is connected to the second voltage source (P2).

9. Braking system according to one of the preceding claims 6 to 8, characterized in that The first servomotor (41) or the second servomotor (42) of the rear wheel brake actuator (BM3, BM4) is connected to a third voltage source (P3), and the corresponding other servomotor (41, 42) of the rear wheel brake actuator (BM3, BM4) is connected to the first voltage source or the second voltage source or to another voltage source (P1, P2).

10. Braking system according to one of the preceding claims 6 to 8, characterized in that The first servomotor (41) of the rear wheel brake actuator (BM3, BM4) is connected to the first voltage source (P1), and the second servomotor (42) of the rear wheel brake actuator (BM3, BM4) is connected to the second voltage source (P2).

11. Braking system according to one of the preceding claims 6 to 8, characterized in that The first servomotor (41) and the second servomotor (42) of the rear wheel brake actuator (BM3, BM4) are connected to a common voltage source (P1, P2, P3).

12. Braking system according to one of the preceding claims, characterized in that The braking unit (1, BU) is connected to a central control unit (112), which is designed to be connected to at least one input device (113, 114), wherein at least two wheel brake control units (120, BC) are provided, each of which is connected to a brake actuator (4) and the wheel brake control units (120, BC) are connected to the central control unit (112).

13. Braking system according to one of the preceding claims, characterized in that The braking device (1) comprises an actuating device (5) and a braking component (32) connected to the actuating device (5), the braking component (32) being adjustable by the actuating device (5) along an axis (A) and being capable of braking engagement with a counter-braking component (2), wherein the actuating device (5) comprises a first actuating drive (6) and a second actuating drive (7) coupled in series to the first actuating drive (6), wherein the first actuating drive (6) comprises a first drive wheel (65) which can be driven in rotation, and the second actuating drive (7) comprises a second drive wheel (75) which can be driven in rotation and is coaxial with the first drive wheel, wherein a coupling device (8, 9) is arranged between the first drive wheel (65) and the second drive wheel (75).

14. Braking system according to one of the preceding claims, characterized in that The brake device (1) has a wheel brake control unit (120) that can be connected to the brake actuator (4) and the wheel sensor (121).

Images