Electromechanical brake device and method for operating same

Abstract

The invention relates to an electromechanical brake device (1) for a motor vehicle, comprising an actuator (5) and a brake element (32) connected thereto, which brake element can be adjusted by the actuator (5) along an axis (A) and can form a braking engagement with a counter brake element (2); the actuator (5) has a first actuator drive (6) and a second actuator drive (7) connected in series therewith, the first actuator drive (6) having a first rotatably drivable drive wheel (65) and the second actuator drive (7) having a second rotatably drivable drive wheel (75) coaxial to the first drive wheel. And clutch devices (8, 9) are arranged between the first driving wheel (65) and the second driving wheel (75). In order to achieve an improved adjustment of the air gap, the invention proposes that the clutch device is designed as a friction clutch (8, 9) having a friction element (8) which can form a frictional connection with the counter friction element (9) during the clutch engagement.

Description

BACKGROUND OF THE INVENTION

[0001] The present invention relates to an electromechanical braking device for a motor vehicle, which device comprises an actuating device and a brake component connected thereto, said brake component being adjustable by the actuating device along an axis and being capable of forming a braking engagement with a counter brake component, wherein the actuating device has a first actuating drive and a second actuating drive connected in series therewith, wherein the first actuating drive has a rotatably drivable first drive wheel, the second actuating drive has a rotatably drivable second drive wheel coaxial with the first drive wheel, and a clutch device is provided between the first drive wheel and the second drive wheel.

[0002] Such a braking device for a motor vehicle is designed as a friction brake, wherein a brake component is mounted on the chassis and is fixed relative to the rotation of the wheel to be braked, and said brake component can form a braking engagement with a counter brake component rotating with the wheel by means of the actuating device. During the braking engagement, frictional contact is generated between the brake component and the counter brake component, and the greater the braking torque generated, the higher the adjusting force exerted by the actuating device in the adjusting direction.

[0003] The widely used disc brake is based on this principle, wherein the counter brake component consists of a brake disc rotating with the wheel, which brake disc is axially surrounded by a caliper on both sides. By means of at least one preferably linearly driven drive mechanism, which is axially supported on the caliper, the brake component (usually a brake lining) can be adjusted in the axial adjusting direction so as to form frictional contact with one axial side of the brake disc, and during the braking engagement, the brake disc is clamped between the adjusted brake component and another brake component, which is axially supported in the opposite direction relative to the caliper.

[0004] A necessary prerequisite for the satisfactory functioning of the braking system and a very precise braking response is that, in the non-operating state, a specific distance - the so-called air gap - must be 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 direction until the air gap is overcome and frictional contact is achieved, thereby producing a braking engagement.

[0005] In order to achieve a repeatable and very precise braking response during driving, it is crucial that the air gap has a specific gap width in the unpowered state, which is measured along the axial adjustment direction. This gap width may increase during use, for example due to wear of the brake linings, and thus corresponding readjustment is required. For the adjustment of the air gap, it is known from German Patent DE 10 2017 123 266A1 that its actuating device arranges two actuating drives in series in the adjustment direction. Each actuating drive includes a drive element on the drive side and an output element on the output side, and the output element can be linearly adjusted relative to the drive element along the axial adjustment direction. To achieve the adjustment movement, each drive element is equipped with a drive wheel, preferably a transmission wheel, such as a gear, etc., which can be rotationally driven about its axis by an electric drive motor. The rotation of the drive wheel is converted in each actuating drive into a relative adjustment movement or drive stroke of the output element relative to the drive element in the axial adjustment direction. In the prior art, the two drive wheels of the first and second actuating drives are coaxially mounted on a common axis extending in the axial adjustment direction.

[0006] Each actuating drive constitutes a lifting or adjusting device that acts axially in the adjustment direction. For example, the actuating drive can be a lead screw drive mechanism, where the drive element has a lead screw nut and the output element has a threaded lead screw meshing with it, or vice versa. Other types of actuating drives can also be used, such as ramp bearings, cam disks, wobble pin devices or similar devices, which can also convert the rotation of the drive element into a linear adjustment action of the output element.

[0007] Since the drive element of the second actuating drive is coupled to the output element of the first actuating drive and the braking element is mounted on the output element of the second actuating drive, by driving the first actuating drive, the braking element can be adjusted linearly together with the second actuating drive to achieve braking engagement. The adjustment of the air gap can be achieved independently of the drive of the first actuating drive through the adjustment of the second actuating drive. Therefore, the first actuating drive can continuously operate within the optimal working range.

[0008] Another advantage brought by the two coupled actuating mechanisms is that a redundant design can be achieved. For example, the second actuating drive, which is only used for adjusting the air gap during normal operation, can in principle also be used to generate braking engagement.

[0009] In order to achieve synchronous rotation of the first drive element and the second drive element during normal operation, with the second actuating drive following as a whole without being adjusted, it was proposed in the aforementioned German patent DE 10 2017 123 266 A1 to provide a ratchet clutch between the first drive wheel and the second drive wheel. In this way, the two drive wheels can be coupled in their respective locking positions, which are locked by releasable form-fit, thus enabling reliable torque transmission during synchronization. However, when adjusting the air gap, the preset discrete locking positions must be overcome. The disadvantage of this design is that the air gap can only be adjusted stepwise, so the continuous wear of the braking element cannot be compensated satisfactorily. In addition, a relatively large driving torque is required to overcome the locking positions.

[0010] Taking the above problems into account, the object of the present invention is to achieve an improved adjustment of the air gap. Summary of the Invention

[0011] According to the present invention, this object is achieved by a braking device having the features of claim 1 and a method of operating the braking device according to claim 12. Preferred further improvements can be seen from the dependent claims.

[0012] In an electromechanical braking device for a motor vehicle, including an actuating device and a braking component connected thereto, the braking component can be adjusted by the actuating device along an axis and can form a braking engagement with an opposing braking component. Among them, the actuating device has a first actuating drive and a second actuating drive connected in series therewith. The first actuating drive has a rotatably drivable first drive wheel, and the second actuating drive has a rotatably drivable second drive wheel coaxial with the first drive wheel. A clutch device is provided between the first drive wheel and the second drive wheel. According to the present invention, the clutch device is designed as a friction clutch with friction elements, and the friction elements can form a friction connection with opposing friction elements during the clutch engagement.

[0013] In the following content, the first drive wheel and the second drive wheel are collectively referred to as "two drive wheels" or simply as "drive wheels".

[0014] The drive wheels can be designed as gears, such as spur gears, or as pulleys, toothed pulleys, worm gears. Therefore, they are usually set as transmission wheels, and the driving torque can be coupled into the drive mechanism from the electric drive motor through the transmission wheels.

[0015] According to the present invention, a friction clutch is implemented between two drive wheels. The friction clutch includes a friction element that is torque-locked to one of the drive wheels and a corresponding opposing friction element that is torque-locked to the other drive wheel. The friction element can be frictionally engaged with the opposing friction element at any relative angular position. In this case, a pure force-fit coupling is achieved, rather than the positive locking connection in the prior art. Therefore, different from the discrete gear positions in the prior art, the relative position between the drive wheels can be continuously preset. Correspondingly, a uniform and continuous adjustment of the second actuating drive relative to the first actuating drive can be achieved, and a continuous adjustment of the air gap can be realized. This characteristic has significant advantages during the operation of the braking device - it can ensure that the optimal operating point of the braking device always synchronously tracks the continuous wear of braking components such as brake linings, thereby achieving an optimized operating state. Compared with the prior art solutions that can only be adjusted periodically, the present invention can continuously optimize the response characteristics of the braking device, thereby significantly improving the operating reliability and operating comfort.

[0016] Another advantage of the present invention compared with the ratchet clutch described in the prior art is that when engaging and releasing the clutch device, there is basically no need for axial relative movement between the components participating in the clutch engagement, such as between the drive wheels or the locking elements. In the prior art, these components must move relative to each other to achieve or release the lockable form fit. On the other hand, according to the present invention, the pure force-fit characteristic between the friction element and the opposing friction element can be simply set only by applying an axial driving force, and there is no need for axial relative movement between them. This characteristic makes the structural design of the clutch device simpler and more reliable.

[0017] Preferably, the friction clutch has a preset clutch torque. The clutch torque defines the maximum differential torque that can be transmitted in a force-fit manner through frictional connection between the friction element and the opposing friction element during the clutch engagement. When the clutch torque is exceeded, the clutch device will slip, and thus relative rotation will occur between the two drive wheels. The advantage is that the friction clutch described in the present invention can continuously slip, and therefore an improved and uniform re-adjustable air gap can be achieved. In addition, different from the known ratchet clutch, there is no need to structurally consider and absorb the axial offset movement of the locking elements.

[0018] Preferably, the friction element and the opposing friction element are arranged coaxially. This coaxial arrangement corresponds to the coaxial arrangement of the drive wheels. The friction element and the opposing friction element can be simply and compactly installed in two end face regions axially opposite to the drive wheels. Due to the aforementioned pure force-fit clutch structure, this structure does not require any moving parts required by the ratchet clutch in the prior art at all.

[0019] In a preferred embodiment, the friction element and the opposing friction element can be arranged in a conical structure. The friction element has at least one conical section that tapers in the axial adjustment direction. This section is provided with a conical friction surface, which can be designed as an outer conical surface or an inner conical surface; the opposing friction element is provided with a corresponding matching conical section, whose conical direction is designed as an inner conical surface or an outer conical surface in the opposite direction and has a conical opposing friction surface. To achieve clutch engagement, the outer conical surface enters the inner conical surface, and a frictional load is generated between the conical friction surface and the opposing friction surface by the axial driving force of the clutch device. One advantage of this design is that the axial force of the clutch can be converted into the normal force between the conical friction surfaces during frictional contact through the conical structure. Therefore, even with a relatively small axial force and a relatively gentle conical slope, a larger normal force can be generated during frictional contact, so that a relatively high clutch torque can be achieved with only a relatively small axial force of the clutch.

[0020] As an alternative or additional solution to the above embodiment, the friction element and the opposing friction element can be set to a planar structure. Their mutually corresponding friction surfaces are at least partially designed as flat axial surfaces similar to those of a disc clutch. Especially in the case where only a relatively small clutch torque needs to be achieved, this structure can realize a space-saving arrangement.

[0021] Preferably, the friction element and the opposing friction element can be pre-tightened against each other. More preferably, the friction element and the opposing friction element are pre-tightened against each other in an elastic or flexible manner. In the friction connection state, the friction surface and the opposing friction surface are pressed against each other by a preset axial pre-tightening force. To generate this pre-tightening force, an elastic pre-tightening element, such as a spring element or a similar structure, can be preferably provided. The clutch torque of this friction clutch depends on the force perpendicular to the friction contact surface, that is, the axial force applied between the friction element and the opposing friction element - the greater the pre-tightening force, the greater the generated clutch torque. This design realizes the advantage of simply setting the clutch torque by the pre-tightening force applied by the pre-tightening element. For example, for an axially compressible and elastically deformable spring element, such as a compression spring, the pre-tightening force it applies can be simply set and adjusted by the spring stiffness coefficient and the compression amount.

[0022] The above-described embodiment can preferably be implemented as follows: The friction element and / or the counter friction element are axially movable and are supported on the first drive wheel or the second drive wheel by an axially effective spring element. The friction element or the counter friction element is torque-locked and axially movable connected to one of the drive wheels, for example, by a radially protruding driver acting in the circumferential direction to form a positive fit. The spring element is axially clamped between the friction element or the counter friction element and the drive wheel, and is preferably an axially acting compression spring, which ensures that the friction element or the counter friction element is axially preloaded against the corresponding friction element or counter friction element supported by the other drive wheel during frictional contact, i.e., is axially pressed. The corresponding counter friction element or friction element is rotatably connected to the other drive wheel. It is also possible to alternatively or additionally support the counter friction element on a certain drive wheel by a spring element. The advantage of this arrangement is that the friction clutch according to the present invention can be integrated between the two drive wheels in a simple and space-saving manner.

[0023] In an advantageous refinement, the friction element and / or the counter friction element can be arranged in the first drive wheel or the second drive wheel. For example, the drive wheel can be designed to be substantially drum-shaped, so that the friction element or the counter friction element is arranged inside the cavity surrounded by the rotating gear or toothed ring. This enables a design that is compact and effectively resistant to external influences. For example, the drive wheel of the first actuating drive can have a conical friction element that meshes axially with the counter friction element, which is designed as an inner cone structure and is at least partially installed inside the second drive wheel.

[0024] In particular, in the above-described embodiment, a particularly compact structural design can be achieved, that is, the drive wheel is arranged within the axial range of the actuator, rather than being installed in a manner that axially protrudes to one side.

[0025] Preferably, the friction element and / or the counter friction element are provided with friction linings. The friction element and the counter friction element preferably have a metal matrix, for example, made of steel. To avoid metal-to-metal contact, a coating or lining can be preferably applied to form a friction pair with a set frictional force, for example, made of sintered materials, metal and / or ceramic friction materials, composite materials, etc. This can ensure a stable and reproducible clutch torque.

[0026] The actuating drive can be provided as a lead screw drive. In this case, the device is implemented in a known manner: The threaded lead screw meshes in the lead screw nut and relative rotational drive is achieved through the drive wheel connected to the threaded lead screw or the lead screw nut. The lead screw nut can constitute the drive-side drive element of the actuating drive mechanism, and the threaded lead screw constitutes the output element on the output side, and the two can be adjusted for relative linear displacement, and vice versa.

[0027] The actuating drive can also employ a wedge disk device, a ball ramp device or an inclined pin device. In a ball ramp device (also known as a ramp bearing), the drive element and the output element preferably have cam disks with raceways or ramps, between which balls that can roll in the circumferential direction are provided. Since the balls roll on the ramps, relative rotation will cause the output element to be displaced axially relative to the drive element. In a known inclined pin device, the inclined pins are arranged between the drive element and the output element and are supported in a specific manner in the circumferential direction such that, upon relative rotation, depending on the direction of rotation, the inclined pins will be inclined to the axis to a corresponding extent, thereby enabling the distance between the drive element and the output element to be adjustable.

[0028] In the actuating device, two actuating drives with the same function can be used in combination as a first actuating drive and a second actuating drive, for example, two lead screw drive mechanisms. Different structural forms can also be combined, for example, using a ball ramp device as the first actuating drive and a lead screw drive as the second actuating drive to adjust the air gap. Such a combination can give full play to the characteristic advantages of each structure. For example, non-linear adjustment characteristics and / or partial self-locking characteristics, and / or having a defined dead point or extended position can be achieved at a relatively low cost, thereby realizing a set adjustment path. The realization of the above advantages requires, in some cases, that the air gap can be precisely set, which is not feasible with a pawl clutch in the prior art, but can be easily achieved with the friction clutch according to the present invention.

[0029] In a method for operating an electromechanical braking device, the device has an actuating device that includes a first actuating drive and a second actuating drive connected in series therewith, the actuating device acting on a braking component that can form a braking engagement with an opposing braking component in the axial direction; wherein, the first actuating drive has a first drive wheel that can be rotationally driven and can apply a first driving torque during driving; the second actuating drive has a second drive wheel that can be rotationally driven and is coaxial with the first drive wheel and can apply a second driving torque during driving; a clutch device is provided between the first drive wheel and the second drive wheel. According to the present invention, the clutch device is designed as a friction clutch and has a preset clutch torque. When the torque exceeds the set value, the first drive wheel will slip relative to the second drive wheel. Among them, when operating the first actuating drive, the first drive wheel and the second drive wheel rotate synchronously, so that the second actuating drive remains undriven; while when operating the second actuating drive, the second drive wheel is driven and the first drive wheel remains stationary. At this time, the friction clutch slips and the first actuating drive remains undriven.

[0030] The above features related to the braking device of the present invention can be used alone or in combination to implement the method of the present invention.

[0031] To adjust the first actuating drive, a drive torque can be coupled to the first drive wheel via a first electric actuating motor; correspondingly, the second actuating drive can be driven by a second electric actuating motor.

[0032] In the normal braking mode, the first drive wheel and the second drive wheel rotate synchronously. This synchronization can be achieved in two ways: on the one hand, the first drive wheel and the second drive wheel are driven by the first and second actuating motors with a synchronous driving torque; on the other hand, when driving the first drive wheel, the second drive wheel can follow synchronously through a clutch device as long as the transmitted driving torque is lower than the clutch torque. In this operating mode, the second actuating drive remains undriven and idles as a whole together with the braking element.

[0033] In the method according to the invention, when the clutch torque is exceeded, in order to adjust the air gap, the clutch device can slip in a continuous and uniform sliding manner, which is in contrast to the prior art. For example, this can be achieved by fixing the drive wheel of the first actuating drive (e.g., by a brake or correspondingly activating the first drive motor), while applying a second drive torque greater than the clutch torque to the second drive wheel by the second drive motor. Therefore, the second drive wheel rotates relative to the first drive wheel, and by driving the second actuating drive, the air gap can be continuously and sensitively adjusted, so that the continuous progressive wear of the braking element or the brake lining can be optimally compensated.

[0034] The first drive wheel and the second drive wheel can be coupled in a torque-locking manner through a friction clutch to achieve synchronous drive. In this case, the two drive wheels do not need to be synchronously driven by a drive motor. Any torque difference can be compensated within a predetermined tolerance range.

[0035] A favorable design is that the clutch setting torque value when the first actuating drive is started is higher than the setting value when the second actuating drive is started. The first actuating drive is activated by the synchronous drive of the first and second drive wheels. The friction element and the opposing friction element are preloaded against each other under the elastic force of the spring element. In addition, the adjusting force of the first actuating drive is also opposite to the direction of this spring force, thus generating a relatively high clutch torque. On the other hand, when only the second drive wheel is rotated to adjust the air gap, only the spring force acts, so a lower clutch torque can be set. This helps to more easily adjust the air gap. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Preferred embodiments of the present invention will be further described in detail with reference to the accompanying drawings, in which specifically shown:

[0037] Figure 1 A schematic perspective view of a braking device according to the present invention is shown;

[0038] Figure 2Shows Figure 1 A side view of the braking device shown;

[0039] Figure 3 Shows the Figure 1 Exploded schematic perspective view of the actuator of the braking device shown according to the present invention;

[0040] Figure 4 Shows along Figure 1 The Q-Q cross-sectional view of the braking device shown;

[0041] Figure 5 Shows Figure 1 The exploded schematic perspective view of the first actuator driver of the braking device shown;

[0042] Figure 6 Shows Figure 4 The enlarged partial view of the actuator in

[0043] Figure 7 Shows the second embodiment of the actuator according to the present invention, corresponding Figure 4 To the detailed view. Detailed description

[0044] In the respective figures, the same components are always denoted by the same reference signs, and thus are generally named or mentioned only once in each case.

[0045] Figure 1 Displays the braking device according to the present invention as a whole, in the form of a disc brake. It includes a brake disc 2, which in the sense of the present invention constitutes the opposing braking member and is connected to a vehicle wheel (not shown) that can rotate around an axle R. The brake caliper 3 axially surrounds the two end faces of the brake disc 2.

[0046] Here, the brake disc 2 is designed as a non-ventilated brake disc made of solid material. Alternatively, it can also be designed as an internally ventilated brake disc.

[0047] The electric brake actuator 4 according to the present invention is mounted on the brake caliper 3, and the actuator is Figure 3 Shown in a separate exploded schematic perspective view in Figures 4 to 7 And is described in detail in

[0048] The brake actuator 4 includes an actuator 5 extending in the direction of axis A, and axis A is parallel to axle R, which represents the adjustment direction V of the actuator 5.

[0049] As Figure 4As shown in the cross-sectional view along the A-axis, the brake disc 2 is axially arranged between two brake linings 31 and 32. Among them, the brake lining 31 is fixedly supported on the brake caliper 3 on the side away from the brake actuator 4; while the other brake lining 32, as the braking component described in the present invention, is installed on the actuating device 5 and can be displaced along the axial adjustment direction V shown by the A-axis towards the brake disc 2 to achieve braking engagement, as Figure 4 indicated by the arrow.

[0050] In the undriven state of the braking device 1, there is an axial air gap L between the brake disc 2 and the adjustable brake lining 32, and this gap is shown schematically with an exaggerated width in Figure 4 it.

[0051] The specific structure of the actuating device 5 is as shown in Figure 4 it, and the local enlarged structure is shown in detail in Figure 6 .

[0052] The actuating device 5 includes a first actuating driver 6 and a second actuating driver 7. Among them, the first actuating driver 6 has a ramp bearing, and the second actuating driver 7 is coupled to the former in an axial series manner (relative to the A-axis) and adopts a screw drive structure.

[0053] In the illustrated example, the first actuating driver 6 is configured as a ramp bearing, which includes a driving-side cam disc 61 and an output-side cam disc 62. Among them, the driving-side cam disc 61 is axially supported on the brake actuator 4 and rotates synchronously with it. There are balls 63 between the cam discs 61 and 62. As shown in the exploded view in Figure 5 it, these two cam discs 61 and 62 have ramp-shaped raceways 64 axially opposite to each other, and the raceways are inclined relative to the axis A, and the balls 63 can roll between them. When the upper output-side cam disc 62 in Figure 5 rotates relative to the fixed driving-side cam disc 61 (as shown by the curved arrow in the figure), it will cause the output-side cam disc 62 to linearly move in the adjustment direction V parallel to the axis A. Therefore, as shown in Figure 4 it, through the drive of the first actuating driver 6, the brake lining 32 can achieve braking engagement.

[0054] The cam disc 62 is connected to a coaxial gear 65, and this gear is designed as a spur gear and constitutes the driving wheel in the sense of the present invention.

[0055] The gear 65 is in driving engagement with the first electric actuating motor 41. Thereby, the cam disc 62 can be rotationally driven, so as to achieve the drive of the first actuating driver 6.

[0056] The second actuating drive 7 shown in this embodiment uses a lead screw actuating device, and a threaded lead screw 71 is provided on its output side. The lead screw meshes with the internal thread of a lead screw nut 72 on the drive side. The internal thread is formed inside the output side cam disk 62 of the first actuating drive 6. Therefore, the functions of the cam disk 62 and the lead screw nut 72 are integrated into a single component.

[0057] The threaded lead screw 71 is connected to a coaxially arranged gear 75 through a hub member 74. The gear is rotatably mounted in the brake actuator 4 in an axially fixed manner. The lead screw is coupled to the gear 75 by a drive 73 in a torque-locked but axially movable manner. For example, the drive can be provided with radially protruding protrusions or teeth, and these structures can axially move and engage in the axial slots of the hub member 74.

[0058] Similar to the gear 65, the gear 75 can be designed as a spur gear and is arranged adjacent to it coaxially. The gear 75 is in driving engagement with the second electric actuating motor 42. This realizes the rotational drive of the threaded lead screw 71 and the drive of the second actuating drive 7.

[0059] The threaded lead screw 71 is axially connected to a thrust member 44 through a thrust bearing 43. For example, as shown in the figure, the thrust bearing can be an axial rolling bearing. As Figure 4 shown, the movable brake lining 32 is mounted on the thrust member 44, and the thrust member 44 can also be called a piston.

[0060] The clutch device according to the present invention is provided with a friction element 8, which extends from the cam disk 62 to the second actuating drive 7 as a coaxial conical shoulder. The conical shoulder is provided with a conical friction surface 81 on the outer side of the outer cone. Preferably, the friction element 81 can be integrally formed with the cam disk 62 / nut 72.

[0061] When the clutch is engaged, the friction element 8 forms a friction coupling with the opposing friction element 9. At this time, the conical shoulder axially engages into the matching conical opening of the opposing friction element 9, and a conical friction surface 91 is provided on the inner conical surface of the opening. In the clutch engaged state, the friction surface 81 and the opposing friction surface 91 are in frictional contact with each other, as Figure 6 clearly shown in.

[0062] The opposing friction element 9 is coupled to the gear 75 by a drive 92 in a torque-locked but axially movable manner. The drive 92 can axially move and engage in the corresponding slot 76 of the hub member 74 or the gear 75.

[0063] The spring element 93 is arranged between the gear 75 or the hub member 74 connected thereto and the opposing friction element 9. Due to the elastic force of the spring element in the axial direction, the opposing friction element 9 is elastically pressed against the friction element 8. Thus, the set torque value of the friction clutch formed by the friction element 8 and the opposing friction element 9 according to the present invention is formed.

[0064] And Figure 6 The second embodiment shown from the same perspective is different in the structure and arrangement of the friction surface 81 and the opposing friction surface 91. Both of these friction surfaces are designed as flat axial surfaces, in contrast to the conical surface structure in the first embodiment shown Figure 4 And Figure 6 The operating principle is essentially the same, so the same reference numerals are still used.

[0065] To drive the braking device 1, the gear 65 rotates synchronously with the gear 75, so that the first actuating drive 6 performs a working stroke in the adjustment direction V, so that the brake lining 32 crosses the air gap L and forms a braking engagement with the brake disc 2. The synchronous drive of the gears 65 and 75 can be achieved by synchronously controlling the rotational speeds of the electric actuating motors 41 and 42, or it can also be driven only by a single one of the actuating motors 41 or 42, while the other motor 42 or 41 remains idling. At this time, the clutch frictional engagement between the friction element 8 and the opposing friction element 9 ensures the synchronous rotation of the gears 65 and 75.

[0066] To adjust the width of the air gap L, the gear 65 can be fixed or locked, for example, by correspondingly activating the first actuating motor 41. Subsequently, the gear 75 is rotated relative to the gear 65 by the second actuating motor 42. At this time, the friction clutch will slip in a continuous sliding manner. Thus, the second actuating drive 7 is evenly adjusted, and further the width of the air gap L can also be continuously set and adjusted, for example, to compensate for the wear of the brake lining 32.

[0067] Since the friction element 8 and the opposing friction element 9 are completely or at least partially arranged inside the gears 65 and 75, a particularly compact structural design can be achieved.

[0068] Figures 1 to 7 The shown braking device is a floating caliper brake (also known as a "punch caliper brake"). In this structure, the brake lining 32 is pressed by the thrust member 44, and the brake lining 31 is pressed by the brake caliper 3. The caliper 3 can move relative to the brake disc 2 in the direction of the axis A. Optionally, the technical solution of the present invention can also be used in a fixed caliper brake.

[0069] List of reference numerals

[0070] 1 Braking device

[0071] 2 Brake disc

[0072] 3 Brake caliper

[0073] 31, 32 Brake lining

[0074] 4 Brake actuator

[0075] 41, 42 Actuating motor

[0076] 43 Thrust bearing

[0077] 44 Thrust member (piston)

[0078] 5 Actuating device

[0079] 6 First actuating driver

[0080] 61 Cam disc

[0081] 62 Cam disc (integrally formed with lead screw nut 72)

[0082] 63 Ball

[0083] 64 Raceway

[0084] 65 Gear

[0085] 7 Second actuating driver

[0086] 71 Threaded lead screw

[0087] 72 Lead screw nut (integrally formed with cam disc 62)

[0088] 73 Driver

[0089] 74 Hub component

[0090] 75 Gear

[0091] 76 Groove

[0092] 8 Friction element

[0093] 81 Friction surface

[0094] 9 Opposing friction element

[0095] 91 Opposing friction surface

[0096] 92 Driver

[0097] 93 Spring element

[0098] Axis A

[0099] Axle R

[0100] Adjustment direction V

[0101] Air gap L

Claims

1. An electromechanical braking device (1) for a motor vehicle, comprising an actuating device (5) and a braking member (32) connected thereto, the braking member being adjustable by the actuating device (5) along an axis (A) and being capable of forming a braking engagement with an opposing braking member (2), characterized in that: The actuating device (5) has a first actuating drive (6) and a second actuating drive (7) connected in series therewith, wherein the first actuating drive (6) has a rotatably driven first drive wheel (65), and the second actuating drive (7) has a rotatably driven second drive wheel (75) coaxial with the first drive wheel, and a clutch device (8, 9) is provided between the first drive wheel (65) and the second drive wheel (75), characterized in that the clutch device is designed as a friction clutch (8, 9) having a friction element (8), the friction element (8) being capable of forming a friction connection with an opposing friction element (9) during the clutch engagement.

2. The braking device according to claim 1, characterized in that, The friction clutch (8, 9) has a preset clutch torque.

3. The braking device according to any one of the preceding claims, characterized in that, The friction element (8) and the opposing friction element (9) are arranged coaxially.

4. The braking device according to any one of the preceding claims, characterized in that, The friction element (8) and the opposing friction element (9) are of a conical structure.

5. The braking device according to any one of the preceding claims, characterized in that, The friction element (8) and the opposing friction element (9) are of a planar structure.

6. The braking device according to any one of the preceding claims, characterized in that, The friction element (8) and the opposing friction element (9) are preloaded with respect to each other.

7. The braking device according to claim 6, characterized in that, The friction element (8) and / or the opposing friction element (9) is / are axially movable and is / are supported on the first drive wheel (65) or the second drive wheel (75) by an axially acting spring element (93).

8. The braking device according to claim 6 or 7, characterized in that, The friction element (8) and / or the opposing friction element (9) is / are provided on the first drive wheel (65) or the second drive wheel (75).

9. The braking device according to any one of the preceding claims, characterized in that, The friction element (8) and / or the opposing friction element (9) has a friction lining.

10. The braking device according to any one of the preceding claims, characterized in that, The actuating drive (7) has a lead screw drive structure.

11. The braking device according to any one of the preceding claims, characterized in that, The actuating drive (6) is a wedge disk device, a ball ramp device or an inclined pin device.

12. A method for operating an electromechanical braking device, the braking device having an actuating device (5) which includes a first actuating drive (6) and a second actuating drive (7) connected in series therewith, the actuating device acting on a braking member (32) which can form a braking engagement with an opposing braking member (2) in the direction of the axis (A), Among them, The first actuating drive (6) has a rotatably driven first drive wheel (65) for applying a first driving torque for driving; The second actuating drive (7) has a rotatably driven second drive wheel (75) coaxial with the first drive wheel for applying a second driving torque for driving; and a clutch device is provided between the first drive wheel (65) and the second drive wheel (75); characterized in that: The clutch device is designed as a friction clutch (8, 9) and has a preset clutch torque, when this torque is exceeded, the first drive wheel (65) slips relative to the second drive wheel (75), Among them, when the first actuator (6) is driven, the first driving wheel (65) and the second driving wheel (75) are driven synchronously, so the second actuator (7) remains in an undriven state; When the second actuator (7) is driven, the second driving wheel (75) is driven, while the first driving wheel (65) remains stationary relative thereto, so that the friction clutch slips and the first actuator (6) remains in an undriven state.

13. The method according to claim 12, wherein The first driving wheel (65) and the second driving wheel (75) are coupled by a friction clutch in a torque-locking manner to achieve synchronous driving.

14. The method according to claim 12 or 13, characterized in that, When the first actuator (6) is driven, a relatively high clutch torque is set; when the second actuator (7) is driven, a relatively low clutch torque is set.

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